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  • 1.
    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)
  • 2.
    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.

  • 3.
    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.

  • 4.
    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.

  • 5.
    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. 

  • 6.
    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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  • 7.
    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.

  • 8.
    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.

  • 9.
    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.

  • 10.
    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)
  • 11.
    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.

  • 12.
    Salomonsson, Kent
    et al.
    Department of Product Development, School of Engineering, Jönköping University, Sweden.
    Jarfors, Anders E. W.
    Department of Product Development, School of Engineering, Jönköping University, Sweden.
    Three-dimensional microstructural characterization of cast iron alloys for numerical analyses2018In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 925, p. 427-435Article in journal (Refereed)
    Abstract [en]

    In this paper, we aim at characterizing three different cast iron alloys and their microstructural features, namely lamellar, compacted and nodular graphite iron. The characterization of microscopic features is essential for the development of methods to optimize the behavior of cast iron alloys; e.g. maximize thermal dissipation and/or maximize ductility while maintaining strength. The variation of these properties is commonly analyzed by metallography on two-dimensional representations of the alloy. However, more precise estimates of the morphologies and material characteristics are obtained by three-dimensional reconstruction of microstructures. The use of X-ray microtomography provides an excellent tool to generate high resolution threedimensional microstructure images. The characteristics of the graphite constituent in the microstructure, including the size, shape and connectivity, were analyzed for the different cast iron alloys. It was observed that the lamellar and compacted graphite iron alloys have relatively large connected graphite morphologies, as opposed to ductile iron where the graphite is present as nodules. The results of the characterization for the different alloys were ultimately used to generate finite element models.

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