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  • 1.
    Bae, Juhee
    et al.
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Li, Yurong
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Ståhl, Niclas
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Mathiason, Gunnar
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Kojola, Niklas
    Group function R&I, SSAB, Stockholm, Sweden.
    Using Machine Learning for Robust Target Prediction in a Basic Oxygen Furnace System2020In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 51, no 4, p. 1632-1645Article in journal (Refereed)
    Abstract [en]

    The steel-making process in a Basic Oxygen Furnace (BOF) must meet a combination of target values such as the final melt temperature and upper limits of the carbon and phosphorus content of the final melt with minimum material loss. An optimal blow end time (cut-off point), where these targets are met, often relies on the experience and skill of the operators who control the process, using both collected sensor readings and an implicit understanding of how the process develops. If the precision of hitting the optimal cut-off point can be improved, this immediately increases productivity as well as material and energy efficiency, thus decreasing environmental impact and cost. We examine the usage of standard machine learning models to predict the end-point targets using a full production dataset. Various causes of prediction uncertainty are explored and isolated using a combination of raw data and engineered features. In this study, we reach robust temperature, carbon, and phosphorus prediction hit rates of 88, 92, and 89 pct, respectively, using a large production dataset. © 2020, The Author(s).

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  • 2.
    Bae, Juhee
    et al.
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Mathiason, Gunnar
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Li, Yurong
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Kojola, Niklas
    Group R and I, SSAB, Stockholm, Sweden.
    Ståhl, Niclas
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Understanding Robust Target Prediction in Basic Oxygen Furnace2021In: IEIM 2021: The 2nd International Conference on Industrial Engineering and Industrial Management, New York, NY: Association for Computing Machinery (ACM), 2021, p. 56-62Conference paper (Refereed)
    Abstract [en]

    The problem of using machine learning (ML) to predict the process endpoint for a Basic Oxygen Furnace (BOF) process used for steelmaking has been largely studied. However, current research often lacks both the usage of a rich dataset and does not address revealing influential factors that explain the process. The process is complex and difficult to control and has a multi-objective target endpoint with a proper range of heat temperature combined with sufficiently low levels of carbon and phosphorus. Reaching this endpoint requires skilled process operators, who are manually controlling the heat throughout the process by using both implicit and explicit control variables in their decisions. Trained ML models can reach good BOF target prediction results, but it is still a challenge to extract the influential factors that are significant to the ML prediction accuracy. Thus, it becomes a challenge to explain and validate an ML prediction model that claims to capture the process well. This paper makes use of a complex and full production dataset to evaluate and compare different approaches for understanding how the data can determine the process target prediction. One approach is based on the collected process data and the other on the ML approach trained on that data to find the influential factors. These complementary approaches aim to explain the BOF process to reveal actionable information on how to improve process control.

  • 3.
    Belov, Ilja
    et al.
    Jönköping University, School of Engineering, Jönköping, Sweden.
    Nordh, Andreas
    ZiGrid AB, Nora, Sweden.
    Salomonsson, Kent
    Jönköping University, School of Engineering, Jönköping, Sweden.
    Leisner, Peter
    Jönköping University, School of Engineering, Jönköping, Sweden / SP Technical Research Institute of Sweden, Borås, Sweden.
    Fin‐Tube and Plate Heat Exchangers: Evaluation of Transient Performance2017In: 18th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE), IEEE, 2017Conference paper (Refereed)
    Abstract [en]

    A methodology for evaluation of transient performance of, and comparison between plate heat exchanger and plate-fin-and-tube heat exchanger was developed and realized, including experiment and 3-D simulation. Heat transfer from water to a gas medium was addressed. The heated gas volume was the same for both heat exchanger designs. This was achieved by placing the plate-fin-and-tube heat exchanger into enclosure. The volume average temperature of the gas as function of time was computed. Estimated material cost for the studied designs was at least seven times lower than for the stainless steel plate heat exchanger. The performance of the selected plate-fin-and-tube heat exchanger design was found comparable to the plate heat exchanger, when both fin and tube materials were set to Al, and the enclosure was a light-weight thermal insulator. Transient behavior of the studied heat exchangers should be of interest for micro-grid applications, but also for thermal management in electronic cabinets and data centers.

  • 4.
    Broberg, Patrik
    et al.
    University West, Trollhättan, Sweden.
    Runnemalm, Anna
    University West, Trollhättan, Sweden.
    Analysis algorithm for surface crack detection by thermography with UV light excitation2016In: Quantitative InfraRed Thermography 2016: Abstracts / [ed] Mariusz Kaczmarek; Adam Bujnowski, Gdańsk, Poland: Gdańsk University of Technology , 2016, p. 160-165Conference paper (Refereed)
    Abstract [en]

    Surface crack defects can be detected by IR thermograpgy due to the high absorption of energy within the crack cavity. It is often difficult to detect the defect in the raw data, since the signal easily drowns in the background. It is therefore important to have good analysis algorithms that can reduce the background and enhance the defect. Here an analysis algorithm is presented which significantly increases the signal to noise ratio of the defects and reduces the image sequence from the camera to one image.

  • 5.
    Chauhan, H. S.
    et al.
    Department of Physics, University of Rajasthan, Jaipur, India.
    Ilver, L.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Nilsson, P. O.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Kanski, J.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Karlsson, Krister
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Direct- and inverse-photoemission investigations of the electronic structure of Cd(0001)1993In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 48, no 7, p. 4729-4734Article in journal (Refereed)
    Abstract [en]

    Photoemission and inverse angle-resolved photoemission spectra are presented for Cd(0001). The data are interpreted in terms of interband transitions, density-of-states effects, and excitations of surface states.

  • 6.
    Das, Kallol
    et al.
    University West, Department of Engineering Science, Trollhättan, Sweden.
    Eynian, Mahdi
    University West, Department of Engineering Science, Trollhättan, Sweden.
    Wretland, Anders
    GKN Aerospace Engine Systems AB, Trollhättan, Sweden.
    Effect of tool wear on quality in drilling of titanium alloy Ti6Al4V, Part II: Microstructure and Microhardness2017In: High Speed Machining, E-ISSN 2299-3975, Vol. 3, no 1, p. 11-22Article in journal (Refereed)
    Abstract [en]

    Drilling of Ti6Al4V with worn tools can introduce superficial and easily measured features such as increase of cutting forces, entry and exit burrs and surface quality issues and defects. Such issues were presented in the part I of this paper. In part II, subsurface quality alterations,such as changes of the microstructure and microhardness variation is considered by preparing metallographic sections and measurement, mapping of the depth of grain deformation, and microhardness in these sections. Drastic changes in the microstructure and microhardness were found in sections drilled with drills with large wear lands, particularly in the dry cutting tests. These measurements emphasize the importance of detection of tool wear and ensuring coolant flow in drilling of holes in titanium components.

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  • 7.
    Devotta, Ashwin Moris
    et al.
    R&D Turning, Sandvik Coromant AB, Sandviken, Sweden ; Department of Engineering Science, University West, Trollhättan, Sweden.
    Sivaprasad, Palla Venkata
    R&D, Sandvik Materials Technology AB, Sandviken, Sweden.
    Beno, Tomas
    Department of Engineering Science, University West, Trollhättan, Sweden.
    Eynian, Mahdi
    Department of Engineering Science, University West, Trollhättan, Sweden.
    Hurtig, Kjell
    Department of Engineering Science, University West, Trollhättan, Sweden.
    Magnevall, Martin
    R&D, Sandvik Coromant AB, Sandviken, Sweden ; Department of Mechanical Engineering, Blekinge Institute of Technology, Karlskrona, Sweden.
    Lundblad, Mikael
    R&D, Sandvik Coromant AB, Sandviken, Sweden.
    A modified Johnson-Cook model for ferritic-pearlitic steel in dynamic strain aging regime2019In: Metals, ISSN 2075-4701, Vol. 9, no 5, article id 528Article in journal (Refereed)
    Abstract [en]

    In this study, the flow stress behavior of ferritic-pearlitic steel (C45E steel) is investigated through isothermal compression testing at different strain rates (1 s-1, 5 s-1, and 60 s-1) and temperatures ranging from 200 to 700 °C. The stress-strain curves obtained from experimental testing were post-processed to obtain true stress-true plastic strain curves. To fit the experimental data to well-known material models, Johnson-Cook (J-C) model was investigated and found to have a poor fit. Analysis of the flow stress as a function of temperature and strain rate showed that among other deformation mechanisms dynamic strain aging mechanism was active between the temperature range 200 and 400 °C for varying strain rates and J-C model is unable to capture this phenomenon. This lead to the need to modify the J-C model for the material under investigation. Therefore, the original J-C model parameters A, B and n are modified using the polynomial equation to capture its dependence on temperature and strain rate. The results show the ability of the modified J-C model to describe the flow behavior satisfactorily while dynamic strain aging was operative. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.

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  • 8.
    Dong, Xixi
    et al.
    Brunel Centre for Advanced Solidification Technology (BCAST), Brunel University London, Uxbridge, United Kingdom.
    Feng, Lingyun
    Brunel Centre for Advanced Solidification Technology (BCAST), Brunel University London, Uxbridge, United Kingdom.
    Wanga, Shihao
    Brunel Centre for Advanced Solidification Technology (BCAST), Brunel University London, Uxbridge, United Kingdom.
    Wang, Feng
    School of Metallurgy and Materials, University of Birmingham, Birmingham, United Kingdom.
    Ghasemi, Rohollah
    Husqvarna AB, Huskvarna, Sweden.
    Ji, Gang
    Univ. Lille, CNRS, INRAE, Centrale Lille, UMR 8207 - UMET - Unité Matériaux et Transformations, Lille, France.
    Nyberg, Eric A.
    Kaiser Aluminum, Spokane Valley, WA, United States.
    Ji, Shouxun
    Brunel Centre for Advanced Solidification Technology (BCAST), Brunel University London, Uxbridge, United Kingdom.
    A quantitative strategy for achieving the high thermal conductivity of die-cast Mg-Al-based alloys2022In: Materialia, E-ISSN 2589-1529, article id 101426Article in journal (Refereed)
    Abstract [en]

    A quantitative strategy was reported to design and develop Mg-Al-based alloys to achieve high thermal conductivity, in which the specific RE elements can be introduced to reduce the Al concentration in Mg matrix and to suppress the formation of Mg17Al12 phase through the formation of new intermetallic phases. Based on quantitative calculations, the strategy was demonstrated by a novel die-cast Mg3.2Al4.4La0.4Nd (in wt.%) alloy, which provided the thermal conductivity of 114.3 W/(m∙K) at ambient temperature and 137.5 W/(m∙K) at 300 °C, ∼25% higher than the commercial Mg4Al4RE (AE44) alloy. Meanwhile, the alloy also offered excellent ambient yield strength of 143.2 MPa and elongation of 8.2%, and superior strength and ductility than the AE44 alloy at elevated temperatures.

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  • 9.
    Eynian, Mahdi
    et al.
    University West, Department of Engineering Science, Trollhättan, Sweden.
    Das, Kallol
    University West, Department of Engineering Science, Trollhättan, Sweden.
    Wretland, Anders
    GKN Aerospace Engine Systems AB, Trollhättan, Sweden.
    Effect of tool wear on quality in drilling of titanium alloy Ti6Al4V, Part I: Cutting Forces, Burr Formation, Surface Quality and Defects2017In: High speed machining, E-ISSN 2299-3975, Vol. 3, no 1, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Titanium's Ti6Al4V, alloy is an important material with a wide range of applications in the aerospace industry. Due to its high strength, machining this material for desired quality at high material removal rate is challenging and may lead to high tool wear rate. As a result, this material may be machined with worn tools and the effects of tool wear on machining quality need to be investigated. In this experimental paper, it is shown how drills of various wear levels affect the cutting forces, surface quality and burr formation. Furthermore, it is shown that high cutting forces and high plastic deformation, along with high temperatures that arise in cutting with worn tools may lead to initiation of microscopic cracks in the workpiece material in proximity of the drilling zone.

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  • 10.
    Ghasemi, Rohollah
    Department of Mechanical Engineering, Materials and Manufacturing—Casting, School of Engineering, Jönköping University, Sweden.
    The influence of microstructure on mechanical and tribological properties of lamellar and compacted irons in engine applications2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Lamellar graphite iron (LGI) is commonly used in diesel engine applications such as piston rings–cylinder liner where an excellent combination of physical and tribological properties is essential to avoid scuffing and bore polishing issues. The excellent tribological behaviour of LGI alloys is related to the graphite lamellas, which act as solid lubricant agents by feeding onto the tribosurfaces under sliding conditions. However, increasingly tighter emissions and fuel economy legislations and the higher demands on enhanced power and durability have encouraged both engine designers and manufacturers to introduce pearlitic compacted graphite irons (CGI) as an alternative material replacing LGI, although the poor machinability of pearlitic CGI alloys compared to the LGI remains a challenge.

    The focus of this study is placed on investigating how the microstructure of LGI and CGI alloys affects their mechanical and tribological properties. This was initially undertaken by investigating representative, worn lamellar cast iron piston rings taken from a two-stroke large-bore heavy-duty diesel engine. As known that it is tribologically essential to keep the graphite open under sliding conditions, in particular under starved lubrication regimes or unlubricated conditions to avoid scuffing issues; however, this study revealed the closure of a majority of graphite lamellas; profoundly for those lamellas that were parallel to sliding direction; due to the severe matrix deformation caused by abrasion. Both microindentation and microscratch testing, which were used to crudely simulate the abrasion under starved lubricated condition in combustion chamber, suggested a novel mechanism of activating the graphite lamellas to serve as lubricating agents in which the matrix deformation adjacent to the graphite initially resulted in fracturing and then extrusion of the graphite lamellas.

    Additionally, in order to investigate the relation between matrix constituents, mechanical properties and machinability of cast iron materials, solution-strengthened CGI alloys were produced with different levels of silicon and section thicknesses. The results showed significant improvements in mechanical properties and machinability while deteriorating the ductility. Moreover, multiple regression analysis, based on chemical composition and microstructural characteristics was used to model the local mechanical properties of high Si ferritic CGI alloys, followed by implementing the derived models into a casting process simulation which enables the local mechanical properties of castings with complex geometries. Very good agreement was observed between the measured and predicted microstructure and mechanical properties.

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  • 11.
    Ghasemi, Rohollah
    et al.
    Department of Mechanical Engineering, Materials and Manufacturing—Casting, School of Engineering, Jönköping University, Sweden.
    Elmquist, Lennart
    Department of Mechanical Engineering, Materials and Manufacturing—Casting, School of Engineering, Jönköping University, Sweden ; SinterCast AB (publ), Technical Centre, Katrineholm, Sweden.
    A study on graphite extrusion phenomenon under the sliding wear response of cast iron using microindentation and microscratch techniques2014In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 320, p. 120-126Article in journal (Refereed)
    Abstract [en]

    This study focuses on the graphite flakes extrusion mechanism during microindenting and microscratching of cast iron. Observations on the graphite response under abrasive conditions revealed that the matrix deformation which is occurred during a sliding wear condition could have a significant influence on its lubricating performance. Simple microindentation and microscratch tests were conducted to explore the lamellar graphite contribution to tribofilm formation under abrasive wear conditions. The results obtained showed that induced plastic deformation which developed adjacent to the graphite compressed the lamellas and in turn resulting in extrusion of the graphite from its natural position. Further investigations on both indentation and scratch tests indicated that, surprisingly, the graphite began to be fractured and extruded from the centre of graphite lamellas, irrespective of the lamella size. Additionally, a mechanism was proposed to explain the self-lubricating and the extrusion behaviour of the lamellar graphite as a result of indentation.

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  • 12.
    Ghasemi, Rohollah
    et al.
    Materials and Manufacturing - Casting, School of Engineering, Jönköping University, Sweden.
    Elmquist, Lennart
    Materials and Manufacturing - Casting, School of Engineering, Jönköping University, Sweden.
    Cast iron and the self-lubricating behaviour of graphite under abrasive wear conditions2014In: 10th International Symposium on the Science and Processing of Cast Iron Proceedings, 2014Conference paper (Refereed)
    Abstract [en]

    Cast iron is assessed as a self-lubricating material under sliding conditions. This is due to the graphite particles distributed in the matrix, which come out from their pocket, and form a tribofilm between the mating surfaces, and by which improve the tribological characteristics. In this study, the directionality and the interaction between the graphite and matrix material was investigated by microindentation and microscratch techniques. The results showed that the graphite is fractured and pushed out from the middle of graphite lamellas as a result of indentation. It was also observed that the graphite orientation below the surface intensely influenced the pushing out behaviour. For the graphite oriented toward the indenter position, the effect was more pronounced. Moreover, it was found that a scratch test can be used to investigate and explain the graphite pushing out tendency. The result was used to explain the directionality and closing tendency of the graphite lamellas during sliding.

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  • 13.
    Ghasemi, Rohollah
    et al.
    Department of Mechanical Engineering, Materials and Manufacturing - Casting, School of Engineering, Jönköping University, Sweden.
    Elmquist, Lennart
    Department of Mechanical Engineering, Materials and Manufacturing - Casting, School of Engineering, Jönköping University, Sweden.
    The relationship between flake graphite orientation, smearing effect, and closing tendency under abrasive wear conditions2014In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 317, no 1–2, p. 153-162Article in journal (Refereed)
    Abstract [en]

    Abstract Plastic deformation of the matrix during the wear process results in closing the graphite flakes. In this study, the relationship between the deformation of the matrix and the closing tendency of flake graphite was investigated, both qualitatively and quantitatively. Two representative piston rings, which belonged to the same two-stroke marine engine but were operated for different periods of time, were studied. Initial microstructural observations indicated a uniform distribution of graphite flakes on unworn surfaces, whereas worn surfaces demonstrated a tendency towards a preferred orientation. Approximately 40% of the open flakes of the unworn surfaces were closed during sliding, which may result in the deterioration of the self-lubricating capability of cast iron. Moreover, flakes within the orientation range of 0 to 30° relative to the sliding direction showed a maximum closing tendency when subjected to sliding. The closing tendency gradually decreased as the angle increased, approaching a minimum between 30 and 70°. A slight increase in the closing tendency was observed for flakes with orientations between 70 and 90°. A similar trend was observed on both rings. Furthermore, SEM and EDS analysis indicated substantial deformation of the matrix in the area around the flakes. An insignificant corrosion attack was observed on both worn piston ring surfaces.

  • 14.
    Ghasemi, Rohollah
    et al.
    Department of Mechanical Engineering, Materials and Manufacturing—Casting, School of Engineering, Jönköping University, Sweden.
    Elmquist, Lennart
    SinterCast AB, Sweden.
    Ghassemali, Ehsan
    Department of Mechanical Engineering, Materials and Manufacturing—Casting, School of Engineering, Jönköping University, Sweden.
    Jarfors, Anders E. W.
    Department of Mechanical Engineering, Materials and Manufacturing—Casting, School of Engineering, Jönköping University, Sweden.
    Effect of interaction between lamellar graphite and cat-fines on tribological behaviour of cast iron under abrasion2015In: Proceedings of ITC, 2015Conference paper (Refereed)
  • 15.
    Ghasemi, Rohollah
    et al.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Elmquist, Lennart
    Swerea SWECAST, Jönköping, Sweden.
    Ghassemali, Ehsan
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Salomonsson, Kent
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Jarfors, Anders E. W.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Abrasion resistance of lamellar graphite iron: Interaction between microstructure and abrasive particles2018In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 120, p. 465-475Article in journal (Refereed)
    Abstract [en]

    This study focuses on abrasion resistance of Lamellar Graphite Iron (LGI) using microscratch test under constant and progressive load conditions. The interactions between a semi-spherical abrasive particle, cast iron matrix and graphite lamellas were physically simulated using a sphero-conical indenter. The produced scratches were analysed using LOM and SEM to scrutinise the effect of normal load on resulting scratch depth, width, frictional force, friction coefficient and deformation mechanism of matrix during scratching. Results showed a significant matrix deformation, and change both in frictional force and friction coefficient by increase of scratch load. Furthermore, it was shown how abrasive particles might produce deep scratches with severe matrix deformation which could result in graphite lamella's coverage and thereby deteriorate LGI's abrasion resistance.

  • 16.
    Ghasemi, Rohollah
    et al.
    Jönköping University, School of Engineering, Materials and Manufacturing, Jönköping, Sweden.
    Elmquist, Lennart
    Jönköping University, School of Engineering, Materials and Manufacturing, Jönköping, Sweden.
    Svensson, Henrik
    Swerea SWECAST AB, Materials and Process Development, Jönköping, Sweden.
    König, Mathias
    Scania CV AB, Materials Technology, Södertälje, Sweden.
    Jarfors, Anders E. W.
    Jönköping University, School of Engineering, Materials and Manufacturing, Jönköping, Sweden.
    Mechanical properties of solid solution strengthened CGI2014In: 10th International Symposium on the Science and Processing of Cast Iron Proceedings, 2014Conference paper (Refereed)
    Abstract [en]

    The development of high-performing components is crucial in applications such as heavy vehicle automotive powertrains. In these applications, strength, weight and thermal conductivity is essential properties. Key materials that may fulfil these requirements include cast irons of different grades where in terms of manufacturability and in particular machinability pearlitic grades are difficult due to hardness variation, where a fully ferritic matrix would provide an advantage. To achieve maximum strength a fully ferritic and solid solution strengthened compacted graphite iron (CGI) would provide an interesting alternative to the automotive industry. In the current study, the effect of Si level on mechanical properties in a fully ferritic material was investigated. The influence of section thickness on tensile properties and hardness was investigated. The resulting material was fully ferritic with limited pearlite content. Section thickness influence on nodularity and hence the mechanical properties were also investigated.

  • 17.
    Ghasemi, Rohollah
    et al.
    Jönköping University, School of Engineering, Department of Materials and Manufacturing, Jönköping, Sweden.
    Elmquist, Lennart
    Jönköping University, School of Engineering, Department of Materials and Manufacturing, Jönköping, Sweden.
    Svensson, Henrik
    Swerea SWECAST AB, Materials and Process Development, Jönköping, Sweden.
    König, Mathias
    Scania CV AB, Materials Technology, Södertälje, Sweden.
    Jarfors, Anders E. W.
    Jönköping University, School of Engineering, Department of Materials and Manufacturing, Jönköping, Sweden.
    Mechanical properties of solid solution-strengthened CGI2016In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 29, no 1-2, p. 97-104Article in journal (Refereed)
    Abstract [en]

    Despite the increased usage of pearlitic compacted graphite iron (CGI) in heavy vehicle engines, poor machinability of this material remains as one of the main technical challenges as compared to conventional lamellar iron. To minimise the machining cost, it is believed that solution-strengthened CGI material with a ferritic matrix could bring an advantage. The present study focuses on the effect of solution strengthening of silicon and section thickness on tensile, microstructure and hardness properties of high-Si CGI materials. To do so, plates with thicknesses from 7 to 75 mm were cast with three different target silicon levels 3.7, 4.0 and 4.5 wt%. For all Si levels, the microstructure was ferritic with a very limited pearlite content. The highest nodularity was observed in 7 and 15 mm plate sections, respectively, however, it decreased as the plate thickness increased. Moreover, increasing Si content to 4.5 wt% resulted in substantial improvement up to 65 and 50% in proof stress and tensile strength, respectively, as compared to pearlitic CGI. However, adding up Si content to such a high level remarkably deteriorated elongation to failure. For each Si level, results showed that the Young’s modulus and tensile strength are fairly independent of the plate thickness (30–75 mm), however, a significant increase was observed for thin section plates, particularly 7 mm plate due to the higher nodularity in these sections.

  • 18.
    Ghasemi, Rohollah
    et al.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Hassan, Inamul
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Ghorbani, Arvin
    Bodycote Gothenburg, Angered, Sweden.
    Diószegi, Attila
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Austempered compacted graphite iron — Influence of austempering temperature and time on microstructural and mechanical properties2019In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 767, article id 138434Article in journal (Refereed)
    Abstract [en]

    This study investigates the effect of austempering temperature and time on the microstructural and mechanical properties of unalloyed Compacted Graphite Iron (CGI) with an initially ferritic matrix structure. The as-cast CGI samples were first austenitised at 900 °C for 60 min in a furnace, then austempered in a closed salt bath at three austempering temperatures – 275, 325, and 375 °C – for different times; 30, 60, 90, and 120 min. Tensile properties, Brinell, Vickers and Rockwell C hardness values were evaluated for the as-cast and austempered CGI ones. LOM and SEM, EBSD analysis techniques were used for microstructure and phase analysis. A mixture of acicular ferrite and retained austenite was achieved in the austempered CGI samples. In general, a decrease in austempering temperature resulted in a decrease in retained austenite content, corresponding improvements in hardness and tensile strength, and a decrease in elongation values.

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  • 19.
    Ghasemi, Rohollah
    et al.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Jarfors, Anders E. W.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Scratch behaviour of silicon solid solution strengthened ferritic compacted graphite iron (CGI)2018In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 925, p. 318-325Article in journal (Refereed)
    Abstract [en]

    The present study focuses on scratch behaviour of a conventional pearlitic and a number of solid solution strengthened ferritic Compacted Graphite Iron (CGI) alloys. This was done by employing a single-pass microscratch test using a sphero-conical diamond indenter under different constant normal load conditions. Matrix solution hardening was made by alloying with different contents of Si; (3.66, 4.09 and 4.59 wt%. Si) which are named as low-Si, medium-Si and high-Si ferritic CGI alloys, respectively. A good correlation between the tensile and scratch test results was observed explaining the influence of CGI’s matrix characteristics on scratch behaviour both for pearlitic and fully ferritic solution strengthened ones. Both the scratch depth and scratch width showed strong tendency to increase with increasing the normal load, however the pearlitic one showed more profound deformation compared to the solution strengthened CGI alloys. Among the investigated alloys, the maximum and minimum scratch resistance were observed for high-Si ferritic CGI and pearlitic alloys, respectively. It was confirmed by the scratched surfaces analysed using Scanning Electron Microscopy (SEM) as well. In addition, the indenter’s depth of penetration value (scratch depth) was found as a suitable measure to ascertain the scratch resistance of CGI alloys. 

  • 20.
    Ghasemi, Rohollah
    et al.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Johansson, Jakob
    Division of Production and Materials Engineering, Department of Mechanical Engineering, Lund University, Sweden.
    Ståhl, Jan-Eric
    Division of Production and Materials Engineering, Department of Mechanical Engineering, Lund University, Sweden.
    Jarfors, Anders E. W.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Load effect on scratch micro-mechanisms of solution strengthened Compacted Graphite Irons2019In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 133, p. 182-192Article in journal (Refereed)
    Abstract [en]

    This study investigates the scratch load effect, from 100 to 2000 mN, on micro-mechanisms involved during scratching. A pearlitic and three ferritic Compacted Graphite Irons (CGI) solution strengthened through addition of 3.66, 4.09, and 4.59 Si wt% were investigated. Good correlation was observed between hardness measurements, tensile testing, and scratch results explaining the influence of matrix characteristics on scratch behaviour for investigated alloys. A significant matrix deformation, change in frictional force and scratch coefficient of friction was observed by increase in scratch load. In all cases, microscratch depth and width increased significantly with load increasing, however pearlitic CGI showed most profound deformation, while the maximum and minimum scratch resistances were observed for high-Si ferritic and pearlitic CGI alloys, respectively.

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  • 21.
    Ghasemi, Rohollah
    et al.
    Department of Materials and Manufacturing, school of engineering, Jönköping university, Sweden.
    Olofsson, Jakob
    Department of Materials and Manufacturing, school of engineering, Jönköping university, Sweden.
    Jarfors, Anders E. W.
    Department of Materials and Manufacturing, school of engineering, Jönköping university, Sweden.
    Svensson, Ingvar L.
    Department of Materials and Manufacturing, school of engineering, Jönköping university, Sweden.
    Modelling and simulation of local mechanical properties of high silicon solution-strengthened ferritic compacted graphite iron2017In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 30, no 3, p. 125-132Article in journal (Refereed)
    Abstract [en]

    This study focuses on the modelling and simulation of local mechanical properties of compacted graphite iron cast at different section thicknesses and three different levels of silicon, ranging from about 3.6% up to 4.6%. The relationship between tensile properties and microstructure is investigated using microstructural analysis and statistical evaluation. Models are generated using response surface methodology, which reveal that silicon level and nodularity mainly affect tensile strength and 0.2% offset yield strength, while Young′s modulus is primarily affected by nodularity. Increase in Si content improves both the yield and tensile strength, while reduces elongation to failure. Furthermore, mechanical properties enhance substantially in thinner section due to the high nodularity. The obtained models have been implemented into a casting process simulation, which enables prediction of local mechanical properties of castings with complex geometries. Very good agreement is observed between the measured and predicted microstructures and mechanical properties, particularly for thinner sections.

  • 22.
    Jansson, Johan
    et al.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Olofsson, Jakob
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Salomonsson, Kent
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    On the use of heterogeneous thermomechanical and thermophysical material properties in finite element analyses of cast components2019In: Joint 5th International Conference on Advances in Solidification Processes (ICASP-5) & 5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining (CSSCR-5) 17–21 June 2019, Salzburg, Austria, Institute of Physics Publishing (IOPP), 2019, article id 012076Conference paper (Refereed)
    Abstract [en]

    Cast components generally show a heterogeneous distribution of material properties, caused by variations in the microstructure that forms during solidification. Variations caused by the casting process are not commonly considered in structural analyses, which might result in manufacturing of sub-optimised components with unexpected in-use behaviour. In this paper, we present a methodology which can be used to consider both thermomechanical and thermophysical variations using finite element analyses in cast components. The methodology is based on process simulations including microstructure modelling and correlations between microstructural features and material properties. Local material data are generated from the process simulation results, which are integrated into subsequent structural analyses. In order to demonstrate the methodology, it is applied to a cast iron cylinder head. The heterogeneous distribution of material properties in this component is investigated using experimental methods, demonstrating local variations in both mechanical and physical behaviour. In addition, the strength-differential effect on tensile and compressive behaviour of cast iron is considered in the modelling. The integrated simulation methodology presented in this work is relevant to both design engineers, production engineers as well as material scientists, in order to study and better understand how local variations in microstructure might influence the performance and behaviour of cast components under in-use conditions.

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  • 23.
    Jansson, Johan
    et al.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Olofsson, Jakob
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Salomonsson, Kent
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Simulation-driven product development of cast components with allowance for process-induced material behaviour2020In: Journal of Computational Design and Engineering, E-ISSN 2288-5048, Vol. 7, no 1, p. 78-85Article in journal (Refereed)
    Abstract [en]

    This paper presents a methodology that can be used to consider local variations in thermomechanical and thermophysical material properties, residual stresses, and strength-differential effects in finite element analyses of cast components. The methodology is based on applying process simulations and structural analyses together with experimentally established, or already available literature data, in order to describe element-specific material variations. A cast-iron cylinder head was used in order to evaluate the influence of several simplifications that are commonly performed in computer aided engineering. It is shown that non-trivial errors of a potentially large magnitude are introduced by not considering residual stresses, compressive behaviour, temperature dependence, and process-induced material property variations. By providing design engineers with tools that allow them to consider the complex relationships between these aspects early in the development phase, cast components have the potential to be further optimized with respect to both weight and performance.

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  • 24.
    Jarfors, Anders E. W.
    et al.
    Jönköping University, School of Engineering, Department of Materials and Manufacturing, Jönköping, Sweden.
    Ghasemi, Rohollah
    Husqvarna AB, Huskvarna, Sweden.
    Awe, Samuel
    Automotive Components Floby AB, Floby, Sweden.
    Jammula, Chaitanya Krishna
    Jönköping University, School of Engineering, Department of Materials and Manufacturing, Jönköping, Sweden.
    Comparison between high-pressure die-cast and rheo-cast aluminium-SICp MMC; wear and friction behaviour2021In: La Metallurgia Italiana, ISSN 0026-0843, no 11-12, p. 13-18Article in journal (Refereed)
    Abstract [en]

    Aluminium is essential in automobile industry together with cast iron. Because of its lightweight property and good mechanical properties, aluminium reinforced with silicon carbide have found application as brake discs. Aluminium reinforced with 15%and 20% silicon carbide were high-pressure die-cast (HPDC) and Rheo-HPDC cast in the current paper. Micro-Vickers hardness and Rockwell C hardness showed different trends with the increasing amounts of SiCp-particles. Scratch resistance of the surface on micro-scale was analysed using a micro-scratch test to study the mechanics of the wear process. Reciprocating sliding wear of the composites was considered, using the HPDC cast aluminium with 20% silicon carbide of liquid casting as the sliding surface. The wear showed a combination of abrasive wear and adhesive wear. The metallography of the wear surfaces showed deep abrasive wear grooves. Wear debris from both the surfaces were forming a tribolayer. The formation of this layer decided the friction and wear performance as a result of the abrasive and adhesive wear mechanisms seen both in the micromechanics of the scratch test and in the friction behaviour.

  • 25.
    Jepsen, O.
    et al.
    Max Planck Institut für Festkörperforschung, Stuttgart, Germany.
    Karlsson, Krister
    Max Planck Institut für Festkörperforschung, Stuttgart, Germany.
    Gunnarsson, O.
    Max Planck Institut für Festkörperforschung, Stuttgart, Germany.
    Electronic Structure and Photoemission Spectra of Cu Compounds1993In: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 32, no S3, p. 212-216Article in journal (Refereed)
  • 26.
    Kasvayee, Keivan A.
    et al.
    School of Engineering, Jönköping University, Sweden.
    Ghassemali, Ehsan
    School of Engineering, Jönköping University, Sweden.
    Salomonsson, Kent
    School of Engineering, Jönköping University, Sweden.
    Sujakhu, S.
    School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
    Castagne, S.
    School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
    Jarfors, Anders E. W.
    School of Engineering, Jönköping University, Sweden.
    Strain localization and crack formation effects on stress-strain response of ductile iron2017In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 702, p. 265-271Article in journal (Refereed)
    Abstract [en]

    The strain localization and crack formation in ferritic-pearlitic ductile iron under tension was investigated by in-situ tensile tests. In-situ tensile tests under optical microscope were performed and the onset of the early ferrite-graphite decohesions and micro-cracks inside the matrix were studied. The results revealed that early ferrite-graphite decohesion and micro-cracks inside the ferrite were formed at the stress range of 280–330 MPa, where a kink occurred in the stress-strain response, suggesting the dissipation of energy in both plastic deformation and crack initiation. Some micro-cracks initiated and propagated inside the ferrite but were arrested within the ferrite zone before propagating in the pearlite. Digital Image Correlation (DIC) was used to measure local strains in the deformed micrographs obtained from the in-situ tensile test. Higher strain localization in the microstructure was measured for the areas in which the early ferrite-graphite decohesions occurred or the micro-cracks initiated. © 2017 Elsevier B.V.

  • 27.
    Kasvayee, Keivan A.
    et al.
    School of Engineering, Jönköping University, Sweden.
    Salomonsson, Kent
    School of Engineering, Jönköping University, Sweden.
    Ghassemali, Ehsan
    School of Engineering, Jönköping University, Sweden.
    Jarfors, Anders E. W.
    School of Engineering, Jönköping University, Sweden.
    Microstructural strain distribution in ductile iron; comparison between finite element simulation and digital image correlation measurements2016In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 655, p. 27-35Article in journal (Refereed)
    Abstract [en]

    This paper presents a study on microstructural deformation of a ferritic-pearlitic ductile iron, utilizing in-situ tensile testing, digital image correlation (DIC) and finite element analysis (FEA). For this purpose, the in-situ tensile test and DIC were used to measure local strain fields in the deformed microstructure. Furthermore, a continuum finite element (FE) model was used to predict the strain maps in the microstructure. Ferrite and pearlite parameters for the FE-model were optimized based on the Ramberg-Osgood relation. The DIC and simulation strain maps were compared qualitatively and quantitatively. Similar strain patterns containing shear bands in identical locations were observed in both strain maps. The average and localized strain values of the DIC and simulation conformed to a large extent. It was found that the Ramberg-Osgood model can be used to capture the main trends of strain localization. The discrepancies between the simulated and DIC results were explained based on the; (i) subsurface effect of the microstructure; (ii) differences in the strain spatial resolutions of the DIC and simulation and (iii) abrupt changes in strain prediction of the continuum FE-model in the interface of the phases due to the sudden changes in the elastic modulus. © 2015 Elsevier B.V.

  • 28.
    Kasvayee, Keivan Amiri
    et al.
    School of Engineering, Jönköping University, Sweden.
    Ghassemali, Ehsan
    School of Engineering, Jönköping University, Sweden.
    Salomonsson, Kent
    School of Engineering, Jönköping University, Sweden.
    Sujakhu, Surendra
    Nanyang Technological University, School of Mechanical and Aerospace Engineering, Singapore.
    Castagne, Sylvie
    KU Leuven, Department of Mechanical Engineering, Celestijnenlaan, Leuven, Belgium / Member Flanders Make, Leuven, Belgium.
    Jarfors, Anders E. W.
    School of Engineering, Jönköping University, Sweden.
    Microstructural strain mapping during in-situ cyclic testing of ductile iron2018In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 140, p. 333-339Article in journal (Refereed)
    Abstract [en]

    This paper focuses on local strain distribution in the microstructure of high silicon ductile iron during cyclic loading. In-situ cyclic test was performed on compact-tension (CT) samples inside the scanning electron microscope (SEM) to record the whole deformation and obtain micrographs for microstructural strain measurement by means of digital image correlation (DIC) technique. Focused ion beam (FIB) milling was used to generate speckle patterns necessary for DIC measurement. The equivalent Von Mises strain distribution was measured in the microstructure at the maximum applied load. The results revealed a heterogeneous strain distribution at the microstructural level with higher strain gradients close to the notch of the CT sample and accumulated strain bands between graphite particles. Local strain ahead of the early initiated micro-cracks was quantitatively measured, showing high strain localization, which decreased by moving away from the micro-crack tip. It could be observed that the peak of strain in the field of view was not necessarily located ahead of the micro-cracks tip which could be because of the (i) strain relaxation due to the presence of other micro-cracks and/or (ii) presence of subsurface microstructural features such as graphite particles that influenced the strain concentration on the surface.

  • 29.
    Malakizadi, Amir
    et al.
    Chalmers Institute of Technology, Gothenburg, Sweden.
    Ghasemi, Rohollah
    Department of Mechanical Engineering, Materials and Manufacturing—Casting, School of Engineering, Jönköping University, Sweden.
    Behring, Carsten
    Chalmers Institute of Technology, Gothenburg, Sweden.
    Olofsson, Jakob
    Department of Mechanical Engineering, Materials and Manufacturing—Casting, School of Engineering, Jönköping University, Sweden.
    Jarfors, Anders E. W.
    Department of Mechanical Engineering, Materials and Manufacturing—Casting, School of Engineering, Jönköping University, Sweden.
    Nyborg, Lars
    Chalmers Institute of Technology, Gothenburg, Sweden.
    Machinability of solid solution-strengthened compacted graphite iron: Influence of the microstructure, mechanical properties and cutting conditions on tool wear responseManuscript (preprint) (Other academic)
  • 30.
    Malakizadi, Amir
    et al.
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, Sweden.
    Ghasemi, Rohollah
    Jönköping University, School of Engineering, Department of Materials and Manufacturing, Jönköping, Sweden.
    Behring, Carsten
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, Sweden.
    Olofsson, Jakob
    Jönköping University, School of Engineering, Department of Materials and Manufacturing, Jönköping, Sweden.
    Jarfors, Anders E. W.
    Jönköping University, School of Engineering, Department of Materials and Manufacturing, Jönköping, Sweden.
    Nyborg, Lars
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, Sweden.
    Krajnik, Peter
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, Sweden.
    Effects of workpiece microstructure, mechanical properties and machining conditions on tool wear when milling compacted graphite iron2018In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 410-411, p. 190-201Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to investigate the tool performance when machining compacted graphite iron (CGI) alloys. A comparison was made between solid solution strengthened CGI including various amounts of silicon (Si-CGI) and the pearlitic-ferritic CGI as a reference material. The emphasis was on examining the influence of microstructure and mechanical properties of the material on tool wear in face milling process. Machining experiments were performed on the engine-like test pieces comprised of solid solution strengthened CGI with three different silicon contents and the reference CGI alloy. The results showed up-to 50% lower flank wear when machining Si-CGI alloys, although with comparable hardness and tensile properties. In-depth analysis of the worn tool surfaces showed that the abrasion and adhesion were the dominant wear mechanisms for all investigated alloys. However, the better tool performance when machining Si-CGI alloys was mainly due to a lower amount of abrasive carbo-nitride particles and the suppression of pearlite formation in the investigated solid solution strengthened alloys.

  • 31.
    Nilsson, P. O.
    et al.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Karlsson, Krister
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Rundgren, J.
    Department of Theoretical Physics, Royal Institute of Technology, Stockholm, Sweden.
    Prediction of image-state excitation by secondary beams in inverse-photoemission spectroscopy1993In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 47, no 19, p. 12968-12971Article in journal (Refereed)
    Abstract [en]

    Excitation of image states is predicted to occur frequently in inverse-photoemission spectroscopy due to diffracted electron beams traveling almost parallel to the surface. A simple kinematic model, as well as full calculations using inverse low-energy electron-diffraction theory, show the effect in the case of Cd(0001).

  • 32.
    Olofsson, Jakob
    et al.
    Jönköping University, Sweden.
    Cenni, Riccardo
    Università degli Studi di Modena e Reggio Emilia, Italy.
    Cova, Matteo
    Università degli Studi di Modena e Reggio Emilia, Italy.
    Bertuzzi, Giacomo
    Zanardi Fonderie, Italy.
    Salomonsson, Kent
    Jönkoping University, Sweden.
    Johansson, Joel
    Jönkoping University, Sweden.
    Multidisciplinary shape optimization of ductile iron castings by considering local microstructure and material behaviour2017In: WCSMO12: 12th World Congress of Structural and Multidisciplinary Optimisation / [ed] Kai-Uwe Bletzinger, Sierk Fiebig, Kurt Maute, Axel Schumacher, Thomas Vietor, International Society for Structural and Multidisciplinary Optimization , 2017, no 6, p. 82-, article id 182Conference paper (Refereed)
    Abstract [en]

    During the casting process and solidification of ductile iron castings, a heterogeneous microstructure is formed throughout the casting. This distribution is highly controlled by process related factors, as chemical composition, local solidification conditions, and the geometry of the casting. Geometrical changes to the geometry of the casting thus alters the local mechanical behaviour, as well as the distribution of stresses and strains when the casting is subjected to load. In order to find an optimal geometry, e.g. with reduced weight and increased load-bearing capacity, this interdependency between geometry and local material behaviour needs to be considered and integrated into the optimization method. In this contribution, recent developments in the multidisciplinary integration of casting process simulation, solidification and microstructure modelling, microstructure-based material characterization, Finite Element Analyses (FEA) with local material behaviour and structural optimization techniques are presented and discussed. The effect and relevance of considering the local material behaviour in shape optimization of ductile iron castings is discussed and evidenced by an industrial application. It is shown that by adopting a multidisciplinary optimization approach by integration of casting simulation and local material behaviour into shape optimization, the potential of the casting process to obtain components with high performance and reliability can be enabled and utilized.

  • 33.
    Olofsson, Jakob
    et al.
    Jönköping University, Sweden.
    Cenni, Riccardo
    SACMI IMOLA S.C, Imola, Italy.
    Cova, Matteo
    SACMI IMOLA S.C, Imola, Italy.
    Bertuzzi, Giacomo
    SACMI IMOLA S.C, Imola, Italy.
    Salomonsson, Kent
    Jönköping University, Sweden.
    Johansson, Joel
    Jönköping University, Sweden.
    Multidisciplinary shape optimization of ductile iron castings by considering local microstructure and material behaviour2018In: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 57, no 5, p. 1889-1903Article in journal (Refereed)
    Abstract [en]

    During the casting process and solidification of ductile iron castings, a heterogeneous microstructure is formed throughout the casting. This distribution is strongly influenced by the item geometry and the process related factors, as chemical composition and local solidification conditions. Geometrical changes to the geometry of the casting thus alters the local mechanical behavior and properties, as well as the distribution of stresses and strains when the casting is subjected to load. In order to find an optimal geometry, e.g. with reduced weight and increased load-bearing capacity, this interdependency between geometry and local material behavior needs to be considered and integrated into the optimization method. In this contribution, recent developments in the multidisciplinary integration of casting process simulation, solidification and microstructure modelling, microstructure-based material characterization, finite element structural analyses with local material behavior and structural optimization techniques are presented and discussed. The effect and relevance of considering the local material behavior in shape optimization of ductile iron castings is discussed and evidenced by an industrial application. It is shown that by adopting a multidisciplinary optimization approach by integration of casting simulation and local material behavior into shape optimization, the potential of the casting process to obtain components with high performance and reliability can be enabled and utilized. 

  • 34.
    Olofsson, Jakob
    et al.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Salomonsson, Kent
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Dahle, Arne K.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Mathiesen, Ragnvald H.
    Department of Physics, Faculty of Natural Sciences, Norwegian University of Science and Technology, NTNU, Trondheim, Norway.
    Three-dimensional study of nodule clustering and heterogeneous strain localization for tailored material properties in ductile iron2019In: Joint 5th International Conference on Advances in Solidification Processes (ICASP-5) & 5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining (CSSCR-5) 17–21 June 2019, Salzburg, Austria, Institute of Physics Publishing (IOPP), 2019, article id 012078Conference paper (Refereed)
    Abstract [en]

    Tailored heterogeneous distributions of microstructural features enable extraordinary material performance in biological and physiological structures such as trees, the aortic arch, human teeth and dinosaur skulls. In ductile iron, a heterogeneous distribution in size and morphology of graphite nodules and variations of the fractions of ferrite and pearlite are created during solidification, and varies as a function of parameters such as local cooling rate, segregation and flow. In the current work, the size distribution as well as the orientation and relation between graphite nodules is obtained by a three-dimensional reconstruction of a ductile iron microstructure from X-ray tomography. The effect of the nodule morphology and clustering on the localization of plastic strains is studied numerically using finite element analysis of the reconstructed microstructure. Real castings have a variation in geometry, solidification conditions and are subjected to variations in loads. A framework for optimized geometry and solidification conditions in order to design and deliver castings with tailored local material performance is proposed.

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  • 35.
    Olofsson, Jakob
    et al.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Salomonsson, Kent
    Department of Product Development, School of Engineering, Jönköping University, Sweden.
    Svensson, Ingvar L.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Modelling and simulations of ductile iron solidification-induced variations in mechanical behaviour on component and microstructural level2015In: MCWASP XIV: International Conference on Modelling of Casting, Welding and Advanced Solidification Processes 21–26 June 2015, Awaji island, Hyogo, Japan / [ed] Hideyuki Yasuda, London: Institute of Physics Publishing (IOPP), 2015, p. 1-8Conference paper (Refereed)
    Abstract [en]

    The mechanical behaviour and performance of a ductile iron component is highly dependent on the local variations in solidification conditions during the casting process. Here we show a framework which combine a previously developed closed chain of simulations for cast components with a micro-scale Finite Element Method (FEM) simulation of the behaviour and performance of the microstructure. A casting process simulation, including modelling of solidification and mechanical material characterization, provides the basis for a macro-scale FEM analysis of the component. A critical region is identified to which the micro-scale FEM simulation of a representative microstructure, generated using X-ray tomography, is applied. The mechanical behaviour of the different microstructural phases are determined using a surrogate model based optimisation routine and experimental data. It is discussed that the approach enables a link between solidification- and microstructure-models and simulations of as well component as microstructural behaviour, and can contribute with new understanding regarding the behaviour and performance of different microstructural phases and morphologies in industrial ductile iron components in service.

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  • 36.
    Olofsson, Jakob
    et al.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Salomonsson, Kent
    Department of Product Development, School of Engineering, Jönköping University, Sweden.
    Svensson, Ingvar L.
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    The multi-scale closed chain of simulations – incorporating local variations in microstructure into finite element simulations2016In: TMS 2015 144th Annual Meeting & Exhibition: Supplemental Proceedings / [ed] The Minerals, Metals & Materials Society, Springer International Publishers, Switzerland , 2016, p. 1057-1064Conference paper (Refereed)
    Abstract [en]

    Numerical simulations of component behavior and performance is critical to develop optimized and robust load-bearing components. The reliability of these simulations depend on the description of the components material behavior, which for e.g. cast and polymeric materials exhibit component specific local variations depending on geometry and manufacturing parameters. Here an extension of a previously presented strategy, the closed chain of simulations for cast components, to predict and incorporate local material data into Finite Element Method (FEM) simulations on multiple scales is shown. Manufacturing process simulation, solidification modelling, material characterization and representative volume elements (RVE) provides the basis for a microstructure-based FEM analysis of component behavior and a simulation of the mechanical behavior of the local microstructure in a critical region. It is discussed that the strategy is applicable not only to cast materials but also to injection molded polymeric materials, and enables a common integrated computational microstructure-based approach to optimized components.

  • 37.
    Salomonsson, Kent
    et al.
    Jönköping University, School of Engineering, Materials and Manufacturing, Jönköping, Sweden.
    Olofsson, Jakob
    Jönköping University, School of Engineering, Materials and Manufacturing, Jönköping, Sweden.
    Analysis of Localized Plastic Strain in Heterogeneous Cast Iron Microstructures Using 3D Finite Element Simulations2017In: Proceedings of the 4th World Congress on Integrated Computational Materials Engineering (ICME 2017) / [ed] Paul Mason, Charles R. Fisher, Ryan Glamm, Michele V. Manuel, Georg J. Schmitz, Amarendra K. Singh, Alejandro Strachan, Cham: Springer, 2017, p. 217-225Conference paper (Refereed)
    Abstract [en]

    The design and production of light structures in cast iron with high static and fatigue performance is of major interest in e.g. the automotive area. Since the casting process inevitably leads to heterogeneous solidification conditions and variations in microstructural features and material properties, the effects on multiple scale levels needs to be considered in the determination of the local fatigue performance. In the current work, microstructural features of different cast irons are captured by use of micro X-ray tomography, and 3D finite element models generated. The details of the 3D microstructure differ from the commonly used 2D representations in that the actual geometry is captured and that there is not a need to compensate for 3D-effects. The first objective with the present study is to try and highlight certain aspects at the micro scale that might be the underlying cause of fatigue crack initiation, and ultimately crack propagation, under fatigue loading for cast iron alloys. The second objective is to incorporate the gained knowledge about the microstructural behavior into multi-scale simulations at a structural length scale, including the local damage level obtained in the heterogeneous structure subjected to fatigue load.

  • 38.
    Svensson, Ingvar L.
    et al.
    Materials and Manufacturing - Casting, School of Engineering, Jönköping University, Sweden.
    Salomonsson, Kent
    Product Development - Simulation and Optimization, School of Engineering, Jönköping University, Sweden.
    Mathematical characterization of the tensile deformation curve of cast iron materials2018In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 925, p. 444-450Article in journal (Refereed)
    Abstract [en]

    The manufacturing process gives cast iron castings properties which are dependent on component design, metallurgy and casting method. Factors such as local wall thickness influences the coarseness and type of microstructure and the castings will have local properties depending on the local metallurgical and thermal history. The stress/strain behaviour of cast materials is typically determined by performing a tensile test in a tensile test machine. The deformation behaviour will normally be determined by two mechanisms, namely, elastic and plastic phenomena. The plastic behaviour is based on dislocation movements in the lattice. Commonly, the deformation history of cast iron involves elastic, plastic and crack phases. The cast iron material has a complex microstructure and first order equations cannot be used to predict the deformation during loading. Until methods have been developed, the characterization of complex microstructure materials such as cast iron has to be determined by use of empirical methods. The empirical methods have to couple the internal microstructure and composition of the material with deformation phenomena during loading. The paper will show a method to characterize tensile test curves of cast iron materials which can be used to couple deformation phenomena with for example microstructure. The equations are aimed to make the tensile test curve ready for curve fitting and optimization in two steps. Each stress/strain curve is like a finger print of the material and requires well performed tests and some advices are given. The paper also wants to encourage researchers and people working with tensile testing to get out more of their effort to measure strength of cast iron materials and connect the result to the microstructure of the specimens. 

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  • 39.
    Wollmann, Daniela
    et al.
    Federal University of Technology – Paraná, Curitiba, Brazil.
    Pintaude, Giuseppe
    Federal University of Technology – Paraná, Curitiba, Brazil.
    Ghasemi, Rohollah
    Department of Materials and Manufacturing, School of Engineering, Jönköping University, Sweden.
    Effect of austempering treatment on lubricated sliding contact of compacted graphite iron2020In: SN Applied Sciences, ISSN 2523-3963, E-ISSN 2523-3971, Vol. 2, no 12, article id 1947Article in journal (Refereed)
    Abstract [en]

    Significant research has been done to improve the wear properties of the components used in internal combustion engines. Excessive wear is observed in components such as cylinder liners and rings, which can lead to lower volumetric efficiency of the engine, increase oil consumption, polluting emissions, and scuffing related issues. Since tribological systems in internal combustion engines are complex, the different wear mechanisms involved need to be investigated to improve the life of components. Cast irons are commonly used for engine components, especially compacted graphite irons (CGI) for piston rings and gray cast irons (GCI) for cylinder liners. This work aims to evaluate the tribological behavior of two different microstructures of CGI (pearlitic and ausferritic), sliding on pearlitic GCI. The samples of CGI with different microstructures and hardness were evaluated in a short-stroke reciprocating sliding tester, using Petronas Urania SAE 30 API CF lubricant oil at 100 degrees C for four hours. The characterization of worn surfaces was made using a scanning electron microscope (SEM) and 3D roughness measurements. The coefficient of friction (COF) comparison between the two CGI microstructures showed very similar results with COF =0.11. The pearlitic CGI showed more severe wear than the austempered one, confirmed by SEM images and the difference in topography parameters before and after the tests. Phosphorus, sulfur, and zinc were detected by EDS analyses in the samples' worn-out regions, indicating the formation of tribo-films, which was further confirmed by the friction tests.

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