Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 32468
Production of Spherical Cementite within Bainitic Matrix Microstructures in High Carbon Powder Metallurgy Steels

Authors: O. Altuntaş, A. Güral


The hardness-microstructure relationships of spherical cementite in bainitic matrix obtained by a different heat treatment cycles carried out to high carbon powder metallurgy (P/M) steel were investigated. For this purpose, 1.5 wt.% natural graphite powder admixed in atomized iron powders and the mixed powders were compacted under 700 MPa at room temperature and then sintered at 1150 °C under a protective argon gas atmosphere. The densities of the green and sintered samples were measured via the Archimedes method. A density of 7.4 g/cm3 was obtained after sintering and a density of 94% was achieved. The sintered specimens having primary cementite plus lamellar pearlitic structures were fully quenched from 950 °C temperature and then over-tempered at 705 °C temperature for 60 minutes to produce spherical-fine cementite particles in the ferritic matrix. After by this treatment, these samples annealed at 735 °C temperature for 3 minutes were austempered at 300 °C salt bath for a period of 1 to 5 hours. As a result of this process, it could be able to produced spherical cementite particle in the bainitic matrix. This microstructure was designed to improve wear and toughness of P/M steels. The microstructures were characterized and analyzed by SEM and micro and macro hardness.

Keywords: Powder metallurgy steel, heat treatment, bainite, spherical cementite.

Digital Object Identifier (DOI):

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 834


[1] Ashrafizadeh F., Influence of plasma and gas nitriding on fatigue resistance of plain carbon (Ck45) steel, Surf. Coat. Technol. 174, 1196.1200, (2003).
[2] Wu, M., Tsao, L., Shu, G., Lin, B.: Mater. Sci. Eng. A, 538, 2012, p. 135. Doi :10.1016/j. Msea. 2011.12.113.
[3] Wu, M. W., Tsao, L. C., Chang, S. Y.: Mater. Sci. Eng. A, 565, 2013, p. 196. doi:10.1016/j.msea.2012.12.032.
[4] S. Tekeli, A. Güral. Dry sliding wear behaviour of heat treated iron based powder metallurgy steels with 0.3% Graphite + 2% Ni additions. Materials and Design 28 (2007) 1923–1927.
[5] Altuntaş, O.: Investigation of Spheroidization Heat Treatment Effects on Microstructure and Impact Toughness Properties of High Carbon Powder Metal Steels. (Master Thesis). Ankara, Gazi University Institute of Science and Technology 2013.
[6] Wang, B., Liu, Z. Y., Zhou, X. G., Wang, G. D.: Journal of Iron and Steel Research, 20, 2013, p. 25. doi:10.1016/S1006-706X(13)60107-7.
[7] Wu, T., Wang, M. Z., Gao, Y. W., Li, X. P., Zhao, Y. C., Zou, Q.: Journal of Iron and Steel Research, 19, 2012, p. 60. doi:10.1016/S1006-706X(12)60140-X.
[8] Lv, Z. Q., Wanga, B., Wang, Z. H., Sun, S. H., Fu, W. T.: Mater. Sci. Eng. A, 574, 2013, p. 143. doi:10.1016/j.msea.2013.02.059.
[9] Yi, H. L., Hou, Z. Y., Xu, Y. B., Wu, D., Wang, G. D.: Scripta Materialia, 67, 2012, p. 645. doi:10.1016/j.scriptamat.2012.07.020.
[10] Krauss, G. Steels: Processing, Structure, and Performance, ASM International, (2005).
[11] H. Bhadeshia, New bainitic steels by design, Displac. Phase Transform. Appl. Mater. Eng. (1998)69–78.
[12] C. Pitt, Wear and microstructure relationships in carbide-free bainitic rail steels, (Ph. D. thesis), University of Cambridge, 1999.
[13] X. Feng, F. Zhang, J. Kang, Sliding wear and low cycle fatigue properties of new carbide free bainitic rail steel, Mater. Sci. Technol. 30 (12) (2014) 1410–1418,
[14] S. Bakshi, P. Shipway, H. Bhadeshia, Three-body abrasive wear of fine pearlite, nanostructured bainite and martensite, Wear 308 (2013) 46–53, / 1743284713Y.0000000474.
[15] M. Zhang, H. Gu, Fracture toughness of nanostructured railway wheels, Eng. Fract. Mech.75 (18) (2008) 5113–5121, engfracmech.2008.07.007.
[16] M. Sherif, P. Rivera-Diaz-del Castillo, H. Bhadeshia, H. Huang, S teel alloy WO 2013149657 A1, 2013.
[17] P. Rivera-Diaz-delCastillo, B. Szost, R. Vegter, H. Bhadeshia, Bearing steel WO 2014121836 A1,2014.
[18] C. Garcia-Mateo, F. Caballero, Advanced high strength bainitic steels, Compr. Mater. Process.1 (2014)165–190.
[19] Tu, Meng-Yin, et al. "Comparison of microstructure and mechanical behavior of lower bainite and tempered martensite in JIS SK5 steel." Materials Chemistry and Physics 107.2-3 (2008): 418-425.
[20] Sawa M, Rigney DA. Sliding behavior of dual-phase steels in vacuum and air. Wear 1987;119:369–90.