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Ghasemi, Rohollah, Assistant Professor/Senior lecturerORCID iD iconorcid.org/0000-0003-2698-5445
Publications (10 of 18) Show all publications
Jarfors, A. E. .., Ghasemi, R., Awe, S. & Jammula, C. K. (2021). Comparison between high-pressure die-cast and rheo-cast aluminium-SICp MMC; wear and friction behaviour. La Metallurgia Italiana (11-12), 13-18
Open this publication in new window or tab >>Comparison between high-pressure die-cast and rheo-cast aluminium-SICp MMC; wear and friction behaviour
2021 (English)In: La Metallurgia Italiana, ISSN 0026-0843, no 11-12, p. 13-18Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Associazione Italiana di Metallurgia, 2021
Keywords
ALUMINIUM, METAL MATRIX COMPOSITE, HIGH-PRESSURE DIE-CASTING, RHEOCASTING, WEAR
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-55533 (URN)000739076900003 ()
Available from: 2022-01-13 Created: 2022-01-13 Last updated: 2022-11-03Bibliographically approved
Wollmann, D., Pintaude, G. & Ghasemi, R. (2020). Effect of austempering treatment on lubricated sliding contact of compacted graphite iron. SN Applied Sciences, 2(12), Article ID 1947.
Open this publication in new window or tab >>Effect of austempering treatment on lubricated sliding contact of compacted graphite iron
2020 (English)In: SN Applied Sciences, ISSN 2523-3963, E-ISSN 2523-3971, Vol. 2, no 12, article id 1947Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Springer Nature, 2020
Keywords
Compacted graphite iron, Austempering, Piston rings, Cylinder liners
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-51078 (URN)10.1007/s42452-020-03772-1 (DOI)000587307600004 ()2-s2.0-85100815400 (Scopus ID)HOA;intsam;1505170 (Local ID)HOA;intsam;1505170 (Archive number)HOA;intsam;1505170 (OAI)
Funder
Knowledge Foundation, 20170021
Available from: 2020-11-30 Created: 2020-11-30 Last updated: 2023-03-28Bibliographically approved
Ghasemi, R., Hassan, I., Ghorbani, A. & Diószegi, A. (2019). Austempered compacted graphite iron — Influence of austempering temperature and time on microstructural and mechanical properties. Materials Science & Engineering: A, 767, Article ID 138434.
Open this publication in new window or tab >>Austempered compacted graphite iron — Influence of austempering temperature and time on microstructural and mechanical properties
2019 (English)In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 767, article id 138434Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Austenitising, Austempered CGI, Ausferrite matrix, Retained austenite, Mechanical properties, EBSD
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-46357 (URN)10.1016/j.msea.2019.138434 (DOI)000494052200036 ()2-s2.0-85072385523 (Scopus ID)PP JTH 2019 embargo 24 (Local ID)PP JTH 2019 embargo 24 (Archive number)PP JTH 2019 embargo 24 (OAI)
Available from: 2019-09-25 Created: 2019-09-25 Last updated: 2019-11-20Bibliographically approved
Ghasemi, R., Johansson, J., Ståhl, J.-E. & Jarfors, A. E. .. (2019). Load effect on scratch micro-mechanisms of solution strengthened Compacted Graphite Irons. Tribology International, 133, 182-192
Open this publication in new window or tab >>Load effect on scratch micro-mechanisms of solution strengthened Compacted Graphite Irons
2019 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 133, p. 182-192Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
CGI, Si solution-strengthening, Scratch testing, Deformation micro-mechanisms during scratching
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-42653 (URN)10.1016/j.triboint.2019.01.010 (DOI)000458943500018 ()2-s2.0-85059818887 (Scopus ID)PP JTH 2019 embargo 24 (Local ID)PP JTH 2019 embargo 24 (Archive number)PP JTH 2019 embargo 24 (OAI)
Available from: 2019-01-16 Created: 2019-01-16 Last updated: 2019-03-13Bibliographically approved
Ghasemi, R., Elmquist, L., Ghassemali, E., Salomonsson, K. & Jarfors, A. E. .. (2018). Abrasion resistance of lamellar graphite iron: Interaction between microstructure and abrasive particles. Tribology International, 120, 465-475
Open this publication in new window or tab >>Abrasion resistance of lamellar graphite iron: Interaction between microstructure and abrasive particles
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2018 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 120, p. 465-475Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Lamellar graphite cast iron; Abrasion resistance; Scratch test; Microstructure; Pearlite deformation
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-38473 (URN)10.1016/j.triboint.2017.12.046 (DOI)000428102900046 ()2-s2.0-85041480396 (Scopus ID)
Available from: 2018-01-12 Created: 2018-01-12 Last updated: 2019-02-15Bibliographically approved
Malakizadi, A., Ghasemi, R., Behring, C., Olofsson, J., Jarfors, A. E. .., Nyborg, L. & Krajnik, P. (2018). Effects of workpiece microstructure, mechanical properties and machining conditions on tool wear when milling compacted graphite iron. Wear, 410-411, 190-201
Open this publication in new window or tab >>Effects of workpiece microstructure, mechanical properties and machining conditions on tool wear when milling compacted graphite iron
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2018 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 410-411, p. 190-201Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Casting, CGI, Machinability, Milling, Solution hardening, Tool wear, Graphite, Iron alloys, Mechanical properties, Microstructure, Milling (machining), Pearlite, Silicon alloys, Solid solutions, Wear of materials, Compacted graphite iron, Machining conditions, Machining experiments, Microstructure and mechanical properties, Pearlite formations, Reference material, Cutting tools
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-41217 (URN)10.1016/j.wear.2018.07.005 (DOI)000440030600019 ()2-s2.0-85050005596 (Scopus ID)
Funder
VINNOVA, GNR 2012_137 2.4.2Knowledge Foundation, GNR 20100218
Available from: 2018-08-23 Created: 2018-08-23 Last updated: 2019-02-14Bibliographically approved
Ghasemi, R. & Jarfors, A. E. .. (2018). Scratch behaviour of silicon solid solution strengthened ferritic compacted graphite iron (CGI). Paper presented at 11th International Symposium on the Science and Processing of Cast Iron, SPCI-XI 2017, Jönköping, Sweden, 4-7 September 2017. Materials Science Forum, 318-325
Open this publication in new window or tab >>Scratch behaviour of silicon solid solution strengthened ferritic compacted graphite iron (CGI)
2018 (English)In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, p. 318-325Article in journal (Refereed) Published
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. 

Place, publisher, year, edition, pages
Trans Tech Publications, 2018
Keywords
Abrasion, CGI, Scratch resistance, Scratch testing, Silicon solution strengthening, Cast iron, Ferrite, Graphite, Pearlite, Scanning electron microscopy, Solid solutions, Compacted graphite iron, Diamond indenter, Good correlations, Micro-scratch test, Penetration values, Solution strengthening, Silicon alloys
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-41279 (URN)10.4028/www.scientific.net/MSF.925.318 (DOI)2-s2.0-85050016378 (Scopus ID)HOA JTH 2018 (Local ID)9783035710557 (ISBN)HOA JTH 2018 (Archive number)HOA JTH 2018 (OAI)
Conference
11th International Symposium on the Science and Processing of Cast Iron, SPCI-XI 2017, Jönköping, Sweden, 4-7 September 2017
Funder
Knowledge FoundationVinnova
Available from: 2018-08-28 Created: 2018-08-28 Last updated: 2020-05-29Bibliographically approved
Ghasemi, R., Olofsson, J., Jarfors, A. E. W. & Svensson, I. L. (2017). Modelling and simulation of local mechanical properties of high silicon solution-strengthened ferritic compacted graphite iron. International Journal of Cast Metals Research, 30(3), 125-132
Open this publication in new window or tab >>Modelling and simulation of local mechanical properties of high silicon solution-strengthened ferritic compacted graphite iron
2017 (English)In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 30, no 3, p. 125-132Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Taylor & Francis, 2017
Keywords
casting process simulation, Compacted graphite iron, materials characterisation, solution-strengthened ferrite, tensile properties, Cast iron, Casting, Ferrite, Ferritic steel, Graphite, Iron, Iron compounds, Mechanical properties, Microstructure, Silicon, Local mechanical properties, Microstructures and mechanical properties, Properties and microstructures, Response surface methodology, Yield and tensile strength, Tensile strength
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-34625 (URN)10.1080/13640461.2016.1261520 (DOI)000400800700001 ()2-s2.0-85006957496 (Scopus ID)
Funder
VINNOVA, DNR 2012_137 2.4.2
Available from: 2017-01-09 Created: 2017-01-09 Last updated: 2017-08-14
Ghasemi, R., Elmquist, L., Svensson, H., König, M. & Jarfors, A. E. W. (2016). Mechanical properties of solid solution-strengthened CGI. International Journal of Cast Metals Research, 29(1-2), 98-105
Open this publication in new window or tab >>Mechanical properties of solid solution-strengthened CGI
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2016 (English)In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 29, no 1-2, p. 98-105Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Taylor & Francis, 2016
Keywords
Compacted graphite iron, High-Si ferritic CGI, Mechanical properties, Solid solution strengthening, Ferrite
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-30841 (URN)10.1080/13640461.2015.1106781 (DOI)000377468800016 ()2-s2.0-84978389185 (Scopus ID)
Funder
VINNOVA
Note

Special Issue: Special Issue featuring papers from SPCI10

Available from: 2016-06-23 Created: 2016-06-23 Last updated: 2018-06-08Bibliographically approved
Ghasemi, R. (2016). The influence of microstructure on mechanical and tribological properties of lamellar and compacted irons in engine applications. (Doctoral dissertation). Jönköping: Jönköping University, School of Engineering
Open this publication in new window or tab >>The influence of microstructure on mechanical and tribological properties of lamellar and compacted irons in engine applications
2016 (English)Doctoral 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.

Place, publisher, year, edition, pages
Jönköping: Jönköping University, School of Engineering, 2016. p. 80
Series
JTH Dissertation Series ; 17
Keywords
Cast iron, Si solution-strengthened CGI, microstructure, mechanical properties, modelling and simulation, tribology, abrasive wear, scratch testing
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-32052 (URN)978-91-87289-18-7 (ISBN)
Public defence
2016-11-25, E1405, Jönköping University, School of Engineering, Jönköping, 10:00 (English)
Opponent
Supervisors
Available from: 2016-10-26 Created: 2016-10-26 Last updated: 2016-10-26Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2698-5445

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