Effect of tempering temperature on microstructure and properties of secondary hardening martensitic stainless steel

doi:10.13251/j.issn.0254-6051.2021.09.011

Abstract

Abstract: Considering that the secondary hardening is very sensitive to the tempering temperature, the evolution of microstructure and properties was systematically studied when a Mo-bearing secondary hardening martensitic stainless steel tempered at 250-650 ℃, and the relationships between the microstructure and the mechanical properties were analyzed by using XRD, SEM, TEM and impact testing. In addition, the mechanisms of the toughening by retained austenite and the secondary hardening for the tested steel were discussed in detail. The results show that when tempered at 480-500 ℃, the phenomena of secondary hardening and temper embrittlement appear simultaneously in the tested steel, so the macrohardness and the impact property are respectively above 56 HRC and about 14 J·cm^-2, with the corresponding microstructure being composed of nanometer-sized alloy carbides, lath martensite and retained austenite. The secondary hardening is attributed to dispersion strengthening of nanometer-sized alloy carbides, and about 10% retained austenite in volume fraction is beneficial to improve the impact property. When the tested steel is tempered at temperatures lower or higher than 480-500 ℃, the impact property is relatively higher, but the macrohardness is lower.

Key words: martensitic stainless steel, secondary hardening, tempering temperature, temper brittleness, alloy carbide, retained austenite

CLC Number:

TG142.1

Deng Biao, Chen Peng, Wang Guodong. Effect of tempering temperature on microstructure and properties of secondary hardening martensitic stainless steel[J]. Heat Treatment of Metals, 2021, 46(9): 65-71.

References

[1]裴新军, 程格, 潘新宇, 等. 刀剪用马氏体不锈钢的现状和发展[J]. 热处理, 2020, 35(4): 1-6.
Pei Xinjun, Cheng Ge, Pan Xinyu, et al. Current situation and development of martensitic stianless steel for knifesand scissors[J]. Heat Treatment, 2020, 35(4): 1-6.
[2]宋自力, 杜晓东, 陈翌庆, 等. 7Cr17Mo马氏体不锈钢组织和冲击韧性[J]. 材料热处理学报, 2011, 32(5): 95-99.
Song Zili, Du Xiaodong, Chen Yiqing, et al. Microstructure and impact toughness of 7Cr17Mo martensitic stainless steel[J]. Transactions of Materials and Heat Treatment, 2011, 32(5): 95-99.
[3]Choi Y S, Kim J G, Park Y S. Austenitizing treatment influence on the electrochemical corrosion behavior of 0.3C-14Cr-3Mo martensitic stainless steel[J]. Materials Letters, 2007, 61(1): 244-247.
[4]Deng B, Yang D P, Wang G D, et al. Effects of austenitizing temperature on tensile and impact properties of a martensitic stainless steel containing metastable retained austenite[J]. Materials, 2021, 14(4): 1000.
[5]Bajguirani H. The effect of ageing upon the microstructure and mechanical properties of type 15-5PH stainless steel[J]. Materials Science and Engineering A, 2002, 338(1-2): 142-159.
[6]Akhtar F, Lian Y D, Islam S H, et al. A new kind of age hardenable martensitic stainless steel with high strength and toughness[J]. Ironmaking and Steelmaking, 2007, 34(4): 285-289.
[7]刘振宝, 梁剑雄, 苏杰, 等. 高强度不锈钢的研究及发展现状[J]. 金属学报, 2020, 56(4): 549-557.
Liu Zhenbao, Liang Jianxiong, Su Jie, et al. Research and application progress in ultra-high strength stainless steel[J]. Acta Metallurgica Sinica, 2020, 56(4): 549-557.
[8]Tobata J, Ngo-Huynh K L, Nakada N, et al. Role of silicon in quenching and partitioning treatment of low-carbon martensitic stainless steel[J]. Transactions of the Iron and Steel Institute of Japan, 2012, 52(7): 1377-1382.
[9]Yuan L, Ponge D, Wittig J, et al. Nanoscale austenite reversion through partitioning, segregation and kinetic freezing: Example of a ductile 2 GPa Fe-Cr-C steel[J]. Acta Materialia, 2012, 60(6/7): 2790-2804.
[10]Hidalgo J, Findley K O, Santofimia M J. Thermal and mechanical stability of retained austenite surrounded by martensite with different degrees of tempering[J]. Materials Science and Engineering A, 2017, 690: 337-347.
[11]Minemura T, Inoue A, Masumoto T. Metastable austenite phase in rapidly quenched Fe-Cr-C alloys[J]. Transactions of the Iron and Steel Institute of Japan, 1981, 21(9): 649-655.
[12]Mola J, Cooman B. Quenching and partitioning (Q&P) processing of martensitic stainless steels[J]. Metallurgical and Materials Transactions A, 2013, 44(2): 946-967.
[13]Lemblé P, Pineau A, Castagne J L, et al. Temper embrittlement in 12%Cr martensitic steel[J]. Metal Science, 2013, 13(8): 496-502.
[14]Moura L B, Abreu H, Araújo W S, et al. Embrittlement and aging at 475 ℃ in an experimental superferritic stainless steel with high molybdenum content[J]. Corrosion Science, 2018, 137: 76-82.
[15]Olefjord I. Temper embrittlement[J]. International Materials Reviews, 1978, 23(1): 149-163.
[16]Yoo C H, Lee H M, Chan J W, et al. M₂C precipitates in isothermal tempering of high Co-Ni secondary hardening steel[J]. Metallurgical and Materials Transactions A, 1996, 27(11): 3466-3472.
[17]Ayer R, Machmeier P M. Transmission electron microscopy examination of hardening and toughening phenomena in Aermet 100[J]. Metallurgical Transactions A, 1993, 24(9): 1943-1955.
[18]Shi X, Zeng W, Zhao Q, et al. Study on the microstructure and mechanical properties of Aermet 100 steel at the tempering temperature around 482 ℃[J]. Journal of Alloys and Compounds, 2016, 679: 184-190.
[19]Yang J, Feng H, Guo Z, et al. Effect of retained austenite on the hydrogen embrittlement of a medium carbon quenching and partitioning steel with refined microstructure[J]. Materials Science and Engineering A, 2016, 665: 76-85.
[20]Fan Y H, Zhang B, Yi H L, et al. The role of reversed austenite in hydrogen embrittlement fracture of S41500 martensitic stainless steel[J]. Acta Materialia, 2017, 139: 188-195.