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Designing spherical cementite in bainitic matrix (SCBM) microstructures in high carbon powder metal steels to improve dry sliding wear resistance
Materials Letters 249 (2019) 185–188
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Designing spherical cementite in bainitic matrix (SCBM) microstructures in high carbon powder metal steels to improve dry sliding wear resistance Onur Altuntasß a, Ahmet Güral b,⇑ a b
Gazi University, Vocational School of Technical Sciences, Department of Machine and Metal Technologies, Ankara, Turkey Gazi University, Faculty of Technology, Department of Metallurgical and Materials Engineering, Ankara, Turkey
a r t i c l e
i n f o
Article history: Received 24 March 2019 Received in revised form 22 April 2019 Accepted 24 April 2019 Available online 24 April 2019 Keywords: Wear and tribology Sintering Powder technology Spheroidising and austempering Heat treatment Microstructure
a b s t r a c t Spherical cementite particles in the bainitic matrix in high carbon steel processed by powder metallurgy (PM) method were produced and compared with separately sintered, fully bainitic and spherical cementite in the ferritic matrix microstructures for their microstructure-hardness-dry sliding wear properties. The primary cementite plus dense lamellar pearlite structures were achieved in the sintered specimens. The spherical cementites in the ferritic matrix (SCFM) were obtained by over-tempering of the martensite phase produced by quenching after the sintering process. To produce spherical cementite in the bainitic (SCBM) microstructure, SCFM specimens were partially austenitised at 735 °C over Ac1 eutectoid temperature for 3 min and austempered at 300 °C for 1–2 h. Dry sliding wear resistance behavior of the specimens were examined under the constant load of 10 N at sliding distance of 1500 m. The dry sliding wear resistances of the SCBM specimens were much better than the microstructures produced by conventional heat treatments. Ó 2019 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental procedures
Numerous properties of PM materials such as ductility, tensile, impact, wear and fatigue are directly associated with their pores and morphology, alloy elements they contain and their microstructures [1–4]. Heat treatment widely used in PM carbon steels is quenching plus tempering process [5]. The hardness and toughness are some of the material properties mostly used to control the friction and wear behavior [6]. The hardness and brittleness of the martensite occurring after the quenching process in carbon steels can be controlled by the tempering temperature and time [5,7]. Spherical hard cementite phases might be precipitated in the ferritic matrix of the mild or high carbon steel having heavy cementite and pearlite structure at the end of annealing near Ac1 temperature known as the spheroidizing heat treatment. Moreover, the spherical cementite particles are precipitated by excessively tempering the steels, the initial microstructure of which is martensitic [7,8]. The bainitic microstructure specimens with the same carbon rate and hardness show the best wear resistance [9].
Natural graphite powder of 1.5 in wt% was added to iron powders (NC 100.24/Höganäs AB). This mixture of powders having 0.5 wt% Zn-Stearate was compacted for dry sliding wear test specimens in accordance with ASTM G99 standard. The green specimens having average density of 6.7 g.cm 3 were sintered at 1150 °C under argon gas atmosphere for 20 min. The density value, relative density and Carbon composition quantified by a spectrometer (Q4 Tasman) of the sintered specimen were 7.1 g.cm 3, 91% and 1.47 wt% respectively. Some of the sintered specimens were austenitized at 950 °C for 3 min and then quenched at 300 °C for 60 min in a salt bath to obtain a fully bainitic structure and subsequently quenched at room temperature and coded as FBM. Spherical cementite microstructure in the ferritic matrix (SCFM) in the quenched specimens was achieved by over tempering at 705 °C. As seen in Fig. 1, spherical cementite in the bainitic matrix microstructures (SCBM) evaluated for the first time in the present study were produced by partially austenitising at 735 °C for 3 min over Ac1 temperature and subsequently austempering in salt bath at 300 °C for 1 and 2 h of the SCFM specimens and coded as SCBM1 and SCBM-2, respectively. The polished specimens were etched with 4% Nital and their microstructures were imaged by JEOL JSM-6060 LV SEM. HV1
⇑ Corresponding author. E-mail addresses: [email protected] (O. Altuntasß), [email protected] (A. Güral). https://doi.org/10.1016/j.matlet.2019.04.095 0167-577X/Ó 2019 Elsevier B.V. All rights reserved.
O. Altuntasß, A. Güral / Materials Letters 249 (2019) 185–188
186
Fig. 1. Schematically heat treatment cycle graphics for processing of the SCBM specimens.
macro- and HV0.1 micro-hardness measurement procedures of the specimens were carried out with Shimadzu Vickers Hardness Tester device. The dry sliding wear tests of the specimens prepared in accordance with ASTM G99 were performed at pin-on-disc by UTS TRIBOMETER T10/20 model wear testing machine under the constant load of 10 N and 2,5 m.s 1 sliding speed in the distances up to 1500 m. Then, the specific wear coefficient (K) of the specimens were calculated according to Archard’s wear model [10]. 3. Results and discussion Microstructure of the sintered specimen consists of dense lamella pearlite colonies and primary cementite as seen in
Fig. 2a. The initial microstructures for the production of the spherical cementite particles in the SCFM and SCBM specimens were plate-type martensitic produced by quenching from 950 °C (Fig. 2b). Fig. 2c shows the lower bainitic microstructure of the FBM specimen austempered at 300 °C after fully austenitizing at 950 °C. The microstructure consisting of spherical cementite particles in the ferritic matrix of the SCFM specimen was produced by over-tempering the martensite phase (Fig. 2d). The spherical cementite particles in the bainitic matrix in SCBM-1 and SCBM-2 specimens as shown in Fig. 3a and b, respectively were produced and this study is the first literature to show that the spherical cementite particles in the bainitic matrix improves wear resistance. The purpose of designing such a microstructure by combining tough bainitic and hard spherical cementites is to produce more superior powder metallurgy parts with improved wear resistance, as a candidate for bearing material. As given in Fig. 3, the particle sizes of cementites in SCBM specimens were almost 1 lm and the spherical cementite volume fraction decreased compared with the SCFM specimen. Both primary and secondary cementites existed in the structure of SCFM specimen; however, there was only primary cementites in SCBM specimen. It was seen that in the SCBM-1 and SCBM-2 specimens the spherical cementites grew larger due to the increase in the austempering time (Fig. 3). In the SCFM and SCBM specimens, cementite phases are often spherical but sometimes they tend to wet the ferrite (as indicated with arrow in Figs. 2(d) and 3). It can be speculated that the primary cementite phases, which tend to soak, precipitate at the grain boundaries. The second phase, which does not wet the grain boundaries, has a tendency to wet with the temperature increase and the incomplete wetting can be observed again. However, it is also emphasized that the Fe3C (cementite) phase in the
Fig. 2. SEM microstructures of (a) the sintered specimen, (b) the quenched specimen, (c) the FBM specimen, (d) the SCFM specimen.
O. Altuntasß, A. Güral / Materials Letters 249 (2019) 185–188
187
Fig. 3. SEM microstructures of (a) SCBM-1 and (b) SCBM-2 specimens.
Table 1 The hardness, density and dry sliding wear properties of the specimens. Specimens
Macro-Hardness (HV1)
Matrix Micro Hardness (HV 0.1)
Average Density (g.cm
As- Sintered FBM SCFM SCBM-1 SCBM-2
247 ± 13 442 ± 27 240 ± 12 302 ± 22 372 ± 19
222 ± 8 420 ± 21 207 ± 5 323 ± 3 380 ± 5
7,10 7,15 7,20 7,20 7,20
two-phase regions of the Fe–C alloy (750–900 °C) can almost completely wet the ferrite/ferrite grain boundaries [14,15]. Therefore, in this study, since spheroid cementite particles were produced at 705 °C, they sometimes tend to wet the grain boundaries. The hardness values of the sintered specimen were lower than those of the heat-treated specimens (Table 1). The macro-hardness of the sintered specimen was higher than its micro-hardness because area of indentation in macro-hardness may occur over both pearlite colonies and primer cementites but area of indentation of the indenter used in micro-hardness occur only in pearlite colonies. FBM specimen had the highest hardness value among the other specimens. Carbon composition of the fully bainitic matrix increased in this specimen as it contained no spherical cementite. The micro-hardness in the specimen was relatively lower than the macro-hardness which was thought to be due to the presence of martensitic phases in the partial areas. The SCFM specimen had the lowest hardness value among all specimen because of spherical cementite in the soft ferrite matrix (Table 1). The hardness values of the SCBM specimens were higher than those of the SCFM specimen and partially lower than the FBM specimen. It was observed that both macro- and micro-hardness values increased as the austempering time increased in the SCBM specimen. This result could be attributed to decrease retained austenite and bainitic ferrite. By longer austempering times, the carbon-rich austenite phases decomposes more into a mixture of bainitic ferrite and carbide phases [11]. It was seen that hardness values increased with the increase of austempering time in some studies [12,13]. High wear coefficient was obtained due to the low hardness of the sintered specimen. The wear coefficient decreased in the heat-treated specimens. It is generally known that the hardness of the material is the most important property for controlling the wear resistance [7–10]. However, in the present study it cannot be asserted that there was a direct relationship between the hardness and wear coefficients. Since the sintered and SCFM
3
)
Friction Coefficient (m)
Wear Coefficient (m3.(Nm)
0,61 0,69 0,62 0,74 0,71
37,5 10 22,4 10 28,1 10 11,2 10 9,38 10
1
)
15 15 15 15 15
specimen with softer matrix micro-hardness were the specimens with maximum wear coefficient, FBM specimen with the highest hardness value showed higher wear coefficient than SCBM specimen. The SCBM microstructure was designed and produced to improve wear resistance. This study revealed that the wear properties of SCBM microstructures were more outstanding than other microstructure specimens. In SCBM specimens, the wear coefficient decreased significantly with the increase of austempering time. This can be attributed to the more stable spherical matrix and spheroidal cementite and the completion of the precipitation process of the bainite with further austempering time in the SCBM-2 specimen. The friction coefficient of the SCBM samples is higher than that of both sintered and other heat-treated specimens (Table 1). It is believed that the coefficient of friction can be reduced by increasing the partial austenitizing temperature for the production of the bainite matrix in the SCBM specimens. By increasing the carbon content of the austenite phase, the friction coefficient can be reduced by increasing the hardness of the bainite.
4. Conclusions 1. Spherical cementite in the ferritic matrix (SCBM) microstructures were produced by annealing at 735 °C over Ac1 in c + Fe3C region the microstructure of the produced in SCFM specimens and then austempering at 300 °C. The particle sizes of cementites in all of the spheroidized specimens were almost 1 lm in both microstructures. 2. High wear coefficient was obtained due to the low hardness of the specimen under sintering conditions. It was observed that the wear coefficients of the heat-treated specimens decreased. 3. It was revealed by this study that the wear properties were more outstanding than other microstructure specimens since SCBM microstructures contained both tough bainite and finehard spherical cementite particles.
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O. Altuntasß, A. Güral / Materials Letters 249 (2019) 185–188
Declaration of interests The authors declare that they have no known competing financial interests. Acknowledgements This study has been supported by the Scientific Research Project Program of Gazi University (under Project Number 07/2018-05). The authors are grateful to Gazi University for their financial support and the provision of laboratory facilities. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.matlet.2019.04.095. References [1] U. Pettersson, S. Jacobson, Tribol. Int. 368 (2003) 57–64.
[2] L. Xinmin, O. Ulf, Tribol. Int. 110 (2017) 86–95. [3] M. Wu, L. Tsao, G. Shu, B. Lin, Mater. Sci. Eng. A 538 (2012) 135–144. [4] W. Ming-Wei, T. Lung-Chuan, C. Shih-Ying, Mater. Sci. Eng. A 565 (2013) 196– 202. [5] S. Tekeli, A. Güral, Mater. Des. 28 (2007) 1923–1927. [6] M.M. Khruschov, Wear 28 (1974) 69–88. [7] O. Altuntasß, A. Güral, Kovove Mater. 55 (2017) 303–310. [8] O. Altuntasß, Investigation of spherinization heat treatment effects on microstructure and impact toughness properties on high carbon powder metal steels (Master Thesis), Gazi University Institute of Science and Technology, 2013. [9] L. Xu, N.F. Kennon, Wear 148 (1991) 101–112. [10] J.F. Archard, J. Appl. Phys. 24 (1953) 981–988. [11] J.R. Davis, Cast Irons. ASM Specialty Handbook, first ed., ASM International, 1996. [12] S. Baradari, S.M. Ali Boutorabi, Mater. Design 86 (2015) 603–609. [13] J. Chakraborty, D. Bhattacharjee, I. Manna, Scr. Mater. 59 (2008) 247–250. [14] B.B. Straumal, Y.O. Kucheev, L.I. Efron, A.L. Petelin, J. Dutta Majumdar, I. Manna, J. Mater. Eng. Perform. 21 (5) (2012) 667–670. [15] B.B. Straumal, O.A. Kogtenkova, K.I. Kolesnikova, A.B. Straumal, M.F. Bulatov, A. N. Nekrasov, JETP Lett. 100 (8) (2014) 535–539.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Designing spherical cementite in bainitic matrix (SCBM) microstructures in high carbon powder metal steels to improve dry sliding wear resistance Onur Altuntasß a, Ahmet Güral b,⇑ a b
Gazi University, Vocational School of Technical Sciences, Department of Machine and Metal Technologies, Ankara, Turkey Gazi University, Faculty of Technology, Department of Metallurgical and Materials Engineering, Ankara, Turkey
a r t i c l e
i n f o
Article history: Received 24 March 2019 Received in revised form 22 April 2019 Accepted 24 April 2019 Available online 24 April 2019 Keywords: Wear and tribology Sintering Powder technology Spheroidising and austempering Heat treatment Microstructure
a b s t r a c t Spherical cementite particles in the bainitic matrix in high carbon steel processed by powder metallurgy (PM) method were produced and compared with separately sintered, fully bainitic and spherical cementite in the ferritic matrix microstructures for their microstructure-hardness-dry sliding wear properties. The primary cementite plus dense lamellar pearlite structures were achieved in the sintered specimens. The spherical cementites in the ferritic matrix (SCFM) were obtained by over-tempering of the martensite phase produced by quenching after the sintering process. To produce spherical cementite in the bainitic (SCBM) microstructure, SCFM specimens were partially austenitised at 735 °C over Ac1 eutectoid temperature for 3 min and austempered at 300 °C for 1–2 h. Dry sliding wear resistance behavior of the specimens were examined under the constant load of 10 N at sliding distance of 1500 m. The dry sliding wear resistances of the SCBM specimens were much better than the microstructures produced by conventional heat treatments. Ó 2019 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental procedures
Numerous properties of PM materials such as ductility, tensile, impact, wear and fatigue are directly associated with their pores and morphology, alloy elements they contain and their microstructures [1–4]. Heat treatment widely used in PM carbon steels is quenching plus tempering process [5]. The hardness and toughness are some of the material properties mostly used to control the friction and wear behavior [6]. The hardness and brittleness of the martensite occurring after the quenching process in carbon steels can be controlled by the tempering temperature and time [5,7]. Spherical hard cementite phases might be precipitated in the ferritic matrix of the mild or high carbon steel having heavy cementite and pearlite structure at the end of annealing near Ac1 temperature known as the spheroidizing heat treatment. Moreover, the spherical cementite particles are precipitated by excessively tempering the steels, the initial microstructure of which is martensitic [7,8]. The bainitic microstructure specimens with the same carbon rate and hardness show the best wear resistance [9].
Natural graphite powder of 1.5 in wt% was added to iron powders (NC 100.24/Höganäs AB). This mixture of powders having 0.5 wt% Zn-Stearate was compacted for dry sliding wear test specimens in accordance with ASTM G99 standard. The green specimens having average density of 6.7 g.cm 3 were sintered at 1150 °C under argon gas atmosphere for 20 min. The density value, relative density and Carbon composition quantified by a spectrometer (Q4 Tasman) of the sintered specimen were 7.1 g.cm 3, 91% and 1.47 wt% respectively. Some of the sintered specimens were austenitized at 950 °C for 3 min and then quenched at 300 °C for 60 min in a salt bath to obtain a fully bainitic structure and subsequently quenched at room temperature and coded as FBM. Spherical cementite microstructure in the ferritic matrix (SCFM) in the quenched specimens was achieved by over tempering at 705 °C. As seen in Fig. 1, spherical cementite in the bainitic matrix microstructures (SCBM) evaluated for the first time in the present study were produced by partially austenitising at 735 °C for 3 min over Ac1 temperature and subsequently austempering in salt bath at 300 °C for 1 and 2 h of the SCFM specimens and coded as SCBM1 and SCBM-2, respectively. The polished specimens were etched with 4% Nital and their microstructures were imaged by JEOL JSM-6060 LV SEM. HV1
⇑ Corresponding author. E-mail addresses: [email protected] (O. Altuntasß), [email protected] (A. Güral). https://doi.org/10.1016/j.matlet.2019.04.095 0167-577X/Ó 2019 Elsevier B.V. All rights reserved.
O. Altuntasß, A. Güral / Materials Letters 249 (2019) 185–188
186
Fig. 1. Schematically heat treatment cycle graphics for processing of the SCBM specimens.
macro- and HV0.1 micro-hardness measurement procedures of the specimens were carried out with Shimadzu Vickers Hardness Tester device. The dry sliding wear tests of the specimens prepared in accordance with ASTM G99 were performed at pin-on-disc by UTS TRIBOMETER T10/20 model wear testing machine under the constant load of 10 N and 2,5 m.s 1 sliding speed in the distances up to 1500 m. Then, the specific wear coefficient (K) of the specimens were calculated according to Archard’s wear model [10]. 3. Results and discussion Microstructure of the sintered specimen consists of dense lamella pearlite colonies and primary cementite as seen in
Fig. 2a. The initial microstructures for the production of the spherical cementite particles in the SCFM and SCBM specimens were plate-type martensitic produced by quenching from 950 °C (Fig. 2b). Fig. 2c shows the lower bainitic microstructure of the FBM specimen austempered at 300 °C after fully austenitizing at 950 °C. The microstructure consisting of spherical cementite particles in the ferritic matrix of the SCFM specimen was produced by over-tempering the martensite phase (Fig. 2d). The spherical cementite particles in the bainitic matrix in SCBM-1 and SCBM-2 specimens as shown in Fig. 3a and b, respectively were produced and this study is the first literature to show that the spherical cementite particles in the bainitic matrix improves wear resistance. The purpose of designing such a microstructure by combining tough bainitic and hard spherical cementites is to produce more superior powder metallurgy parts with improved wear resistance, as a candidate for bearing material. As given in Fig. 3, the particle sizes of cementites in SCBM specimens were almost 1 lm and the spherical cementite volume fraction decreased compared with the SCFM specimen. Both primary and secondary cementites existed in the structure of SCFM specimen; however, there was only primary cementites in SCBM specimen. It was seen that in the SCBM-1 and SCBM-2 specimens the spherical cementites grew larger due to the increase in the austempering time (Fig. 3). In the SCFM and SCBM specimens, cementite phases are often spherical but sometimes they tend to wet the ferrite (as indicated with arrow in Figs. 2(d) and 3). It can be speculated that the primary cementite phases, which tend to soak, precipitate at the grain boundaries. The second phase, which does not wet the grain boundaries, has a tendency to wet with the temperature increase and the incomplete wetting can be observed again. However, it is also emphasized that the Fe3C (cementite) phase in the
Fig. 2. SEM microstructures of (a) the sintered specimen, (b) the quenched specimen, (c) the FBM specimen, (d) the SCFM specimen.
O. Altuntasß, A. Güral / Materials Letters 249 (2019) 185–188
187
Fig. 3. SEM microstructures of (a) SCBM-1 and (b) SCBM-2 specimens.
Table 1 The hardness, density and dry sliding wear properties of the specimens. Specimens
Macro-Hardness (HV1)
Matrix Micro Hardness (HV 0.1)
Average Density (g.cm
As- Sintered FBM SCFM SCBM-1 SCBM-2
247 ± 13 442 ± 27 240 ± 12 302 ± 22 372 ± 19
222 ± 8 420 ± 21 207 ± 5 323 ± 3 380 ± 5
7,10 7,15 7,20 7,20 7,20
two-phase regions of the Fe–C alloy (750–900 °C) can almost completely wet the ferrite/ferrite grain boundaries [14,15]. Therefore, in this study, since spheroid cementite particles were produced at 705 °C, they sometimes tend to wet the grain boundaries. The hardness values of the sintered specimen were lower than those of the heat-treated specimens (Table 1). The macro-hardness of the sintered specimen was higher than its micro-hardness because area of indentation in macro-hardness may occur over both pearlite colonies and primer cementites but area of indentation of the indenter used in micro-hardness occur only in pearlite colonies. FBM specimen had the highest hardness value among the other specimens. Carbon composition of the fully bainitic matrix increased in this specimen as it contained no spherical cementite. The micro-hardness in the specimen was relatively lower than the macro-hardness which was thought to be due to the presence of martensitic phases in the partial areas. The SCFM specimen had the lowest hardness value among all specimen because of spherical cementite in the soft ferrite matrix (Table 1). The hardness values of the SCBM specimens were higher than those of the SCFM specimen and partially lower than the FBM specimen. It was observed that both macro- and micro-hardness values increased as the austempering time increased in the SCBM specimen. This result could be attributed to decrease retained austenite and bainitic ferrite. By longer austempering times, the carbon-rich austenite phases decomposes more into a mixture of bainitic ferrite and carbide phases [11]. It was seen that hardness values increased with the increase of austempering time in some studies [12,13]. High wear coefficient was obtained due to the low hardness of the sintered specimen. The wear coefficient decreased in the heat-treated specimens. It is generally known that the hardness of the material is the most important property for controlling the wear resistance [7–10]. However, in the present study it cannot be asserted that there was a direct relationship between the hardness and wear coefficients. Since the sintered and SCFM
3
)
Friction Coefficient (m)
Wear Coefficient (m3.(Nm)
0,61 0,69 0,62 0,74 0,71
37,5 10 22,4 10 28,1 10 11,2 10 9,38 10
1
)
15 15 15 15 15
specimen with softer matrix micro-hardness were the specimens with maximum wear coefficient, FBM specimen with the highest hardness value showed higher wear coefficient than SCBM specimen. The SCBM microstructure was designed and produced to improve wear resistance. This study revealed that the wear properties of SCBM microstructures were more outstanding than other microstructure specimens. In SCBM specimens, the wear coefficient decreased significantly with the increase of austempering time. This can be attributed to the more stable spherical matrix and spheroidal cementite and the completion of the precipitation process of the bainite with further austempering time in the SCBM-2 specimen. The friction coefficient of the SCBM samples is higher than that of both sintered and other heat-treated specimens (Table 1). It is believed that the coefficient of friction can be reduced by increasing the partial austenitizing temperature for the production of the bainite matrix in the SCBM specimens. By increasing the carbon content of the austenite phase, the friction coefficient can be reduced by increasing the hardness of the bainite.
4. Conclusions 1. Spherical cementite in the ferritic matrix (SCBM) microstructures were produced by annealing at 735 °C over Ac1 in c + Fe3C region the microstructure of the produced in SCFM specimens and then austempering at 300 °C. The particle sizes of cementites in all of the spheroidized specimens were almost 1 lm in both microstructures. 2. High wear coefficient was obtained due to the low hardness of the specimen under sintering conditions. It was observed that the wear coefficients of the heat-treated specimens decreased. 3. It was revealed by this study that the wear properties were more outstanding than other microstructure specimens since SCBM microstructures contained both tough bainite and finehard spherical cementite particles.
188
O. Altuntasß, A. Güral / Materials Letters 249 (2019) 185–188
Declaration of interests The authors declare that they have no known competing financial interests. Acknowledgements This study has been supported by the Scientific Research Project Program of Gazi University (under Project Number 07/2018-05). The authors are grateful to Gazi University for their financial support and the provision of laboratory facilities. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.matlet.2019.04.095. References [1] U. Pettersson, S. Jacobson, Tribol. Int. 368 (2003) 57–64.
[2] L. Xinmin, O. Ulf, Tribol. Int. 110 (2017) 86–95. [3] M. Wu, L. Tsao, G. Shu, B. Lin, Mater. Sci. Eng. A 538 (2012) 135–144. [4] W. Ming-Wei, T. Lung-Chuan, C. Shih-Ying, Mater. Sci. Eng. A 565 (2013) 196– 202. [5] S. Tekeli, A. Güral, Mater. Des. 28 (2007) 1923–1927. [6] M.M. Khruschov, Wear 28 (1974) 69–88. [7] O. Altuntasß, A. Güral, Kovove Mater. 55 (2017) 303–310. [8] O. Altuntasß, Investigation of spherinization heat treatment effects on microstructure and impact toughness properties on high carbon powder metal steels (Master Thesis), Gazi University Institute of Science and Technology, 2013. [9] L. Xu, N.F. Kennon, Wear 148 (1991) 101–112. [10] J.F. Archard, J. Appl. Phys. 24 (1953) 981–988. [11] J.R. Davis, Cast Irons. ASM Specialty Handbook, first ed., ASM International, 1996. [12] S. Baradari, S.M. Ali Boutorabi, Mater. Design 86 (2015) 603–609. [13] J. Chakraborty, D. Bhattacharjee, I. Manna, Scr. Mater. 59 (2008) 247–250. [14] B.B. Straumal, Y.O. Kucheev, L.I. Efron, A.L. Petelin, J. Dutta Majumdar, I. Manna, J. Mater. Eng. Perform. 21 (5) (2012) 667–670. [15] B.B. Straumal, O.A. Kogtenkova, K.I. Kolesnikova, A.B. Straumal, M.F. Bulatov, A. N. Nekrasov, JETP Lett. 100 (8) (2014) 535–539.