Carbide dissolution during intercritical austenitization in bearing steel

Abstract

In order to investigate the carbide dissolution mechanism of high carbon-chromium bearing steel during the intercritical austenitization, the database of TCFE7 of Thermo-calc and MOBFE of DICTRA software were used to calculate the elements diffusion kinetic and the evolution law of volume fraction of carbide. DIL805A dilatometer was used to simulate the intercritical heat treatment. The microstructure was observed by scanning electron microscopy(SEM), and the micro-hardness was tested. The experimental results indicate that the dissolution of carbide is composed of two stages: initial austenite growth governed by carbon diffusion which sharply moves up the micro-hardness of quenched martensite, and subsequent growth controlled by diffusion of Cr elements in M₃C. The volume fraction of M₃C decreases with the increasing holding time, and the metallographic analysis shows a great agreement with values calculated by software.

Keywords

intercritical austenitization / carbide dissolution / bearing steel / diffusion mechanism

References

[1] Bhadeshia HKDK Steels for bearings[J]. Prog. Mater. Sci., 2012, 57: 268-270.

[2] Barrow ATW, Rivera PEJ Nanoprecipitation in Bearing Steels [J]. Acta Materialia, 2011, 59: 7 155-7 167.

[3] Chakraborty J, Bhattacharjee D, Manna I Development of Ultrafine Bainite+Martensite Duplex Microstructure in SAE52100 Bearing Steel by Prior Cold Deformation[J]. Scripta Materialia, 2009, 61: 604-607.

[4] Lu LM, Soda H, Mclean A Microstructure and Mechanical Properties of Fe-Cr-C Eutectic Composites[J]. Mater. Sci. Eng. A, 2003, 347: 214-222.

[5] Barrow ATW, Kang JH, Rivera PEJ The ɛ→η→θ transition in 100Cr6 and Its Effect on Mechanical Properties [J]. Acta Materialia, 2012, 60: 2 805-2 815.

[6] Kang JH, Rivera PEJ Carbide Dissolution in Bearing Steels [J]. Comp. Mater. Sci., 2013, 67: 364-372.

[7] Amey CM, Huang H, Rivera PEJ Distortion in 100Cr6 and Nanostructured Bainite [J]. Mater. Design, 2012, 35: 66-71.

[8] Chae JY, Jang JH, Zhang GH, . Dilatometric Analysis of Cementite Dissolution in Hypereutectoid Steels Containing Cr [J]. Scripta Materialia, 2011, 65: 245-248.

[9] Epp J, Surm H, Kessler O, . In situ X-ray Phase Analysis and Computer Simulation of Carbide Dissolution of Ball Bearing Steel at Different Austenitizing Temperatures [J]. Acta Materialia, 2007, 55: 5 959-5 967.

[10] Andres CG, Caballero FG, Capdevila C, . Modelling of Kinetics and Dilatometric Behavior of Non-isothermal Pearlite-to-austenite Transformation in An Eutectoid Steel [J]. Scripta Materialia, 1998, 39: 791-796.

[11] Karmazin L, Krejci J The Dependence of the Austenitization Kinetics on the Type of Initial Spheroidized Structure in Low Alloy steel [J]. Mater. Sci. Eng. A, 1994, 185: L5-L7.

[12] Qian M In-situ Observations of the Dissolution of Carbides in an Fe-Cr-C Alloy [J]. Scripta Materialia, 1999, 41: 1 301-1 303.

[13] Wei R, Enomoto M, Hadian R, . Growth of Austenite from As-quenched Martensite during Intercritical Annealing in An Fe-0.1C-3Mn-1.5Si Alloy [J]. Acta Materialia, 2013, 61: 697-707.

[14] Miyamoto G, Usuki H, Li ZD, . Effects of Mn, Si and Cr Addition on Reverse Transformation at 1 073 K from Spheroidized Cementite Structure in Fe-0.6mass% C Alloy [J]. Acta Materialia, 2010, 58: 4 492-4 502.

[15] Xia Y, Enomoto M, Yang ZG, . Effects of Alloying Elements on the Kinetics of Austenitization from Pearlite in Fe-C-M Alloys [J]. Philos. Mag., 2013, 93: 1 095-1 097.

[16] Atkinson C, Akbay T, Reed RC Theory for Reaustenitisation from Ferrite/Cementite Mixtures in Fe-C-X Steels [J]. Acta Metall. Mater., 1995, 43: 2 013-2 031.