Effect of cold rolling on M/B duplex microstructure and mechanical properties of M50 steel

doi:10.13251/j.issn.0254-6051.2020.11.023

Abstract

Abstract: Effect of cold rolling on the M/B duplex microstructure and mechanical properties of M50 steel was investigated by means of X-ray diffraction, scanning and transmission electron microscopy, uniaxial tensile and Charpy impact tests. The results show that an excellent combination of ultimate tensile strength (2535.7 MPa) and impact property (96.93 J) is achieved by combining 20% cold rolling with austempering, of which the ultimate tensile strength increases by about 5% whereas the impact absorbed energy increases by about 21% compared with the specimen which is not cold rolled. The microstructure observation indicates that with the increase of cold rolling deformation (<20%), the microstructure becomes finer and the specimen with 20% cold rolling deformation shows the finest microstructure. However, when a higher cold rolling deformation (>20%) is applied, the amount of bainite sheaves decreases, which weakens the refinement of martensite and leads to some coarsening of microstructure.

Key words: M50 steel, cold rolling, austempering, M/B duplex microstructure, mechanical properties

CLC Number:

TG162.6

He Yuangeng, Liu Yujian, Xia Yunzhi, Qian Dongsheng, Wang Feng. Effect of cold rolling on M/B duplex microstructure and mechanical properties of M50 steel[J]. Heat Treatment of Metals, 2020, 45(11): 126-131.

References

[1]王金玲, 张书丽. Cr4Mo4V钢制轴承零件的真空热处理工艺[J]. 轴承, 2008(4): 16-17.
Wang Jinling, Zhang Shuli. Vacuum heat treatment process of Cr4Mo4V steel bearing parts[J]. Bearing, 2008(4): 16-17.
[2]吴运榜, 樊志强, 叶健熠. 冷处理对Cr4Mo4V钢尺寸和高温接触疲劳寿命的影响[J]. 特殊钢, 1999, 20(3): 17-20.
Wu Yunbang, Fan Zhiqiang, Ye Jianyi. Effect of cold treatment of steel Cr4Mo4V on dimension and contact fatigue life at high temperature[J]. Special Steel, 1999, 20(3): 17-20.
[3]杨培基, 吴运榜. Cr4Mo4V高温轴承钢热处理工艺及性能的研究[J]. 特殊钢, 1980(2): 64-81.
Yang Peiji, Wu Yunbang. Study on heat treatment process and properties of Cr4Mo4V high temperature bearing steel[J]. Special Steel, 1980(2): 64-81.
[4]王兴刚, 葛泉江. 航空发动机主轴轴承工作特点[J]. 哈尔滨轴承, 2006(4): 3-4.
Wang Xinggang, Ge Quanjiang. Working characteristic of spindle bearing for aviation engine[J]. Journal of Harbin Bearing, 2006(4): 3-4.
[5]Zhao J, Wang T S, Lü B, et al. Microstructures and mechanical properties of a modified high-C-Cr bearing steel with nano-scaled bainite[J]. Materials Science and Engineering A, 2015, 628: 327-331.
[6]Wei D Y, Gu J L, Fang H S, et al. Fatigue behavior of 1500 MPa bainite+martensite duplex-phase high strength steel[J]. International Journal of Fatigue, 2004, 26: 437-442.
[7]Young C H, Bhadeshia H K D H. Strength of mixtures of bainite and martensite[J]. Materials Science and Technology, 1994, 10: 209-214.
[8]Chakraborty J, Bhattacharjee D, Manna I. Development of ultrafine bainite+martensite duplex microstructure in SAE 52100 bearing steel by prior cold deformation[J]. Scripta Materialia, 2009, 61: 604-607.
[9]Tsuji N, Maki T. Enhanced structural refinement by combining phase transformation and plastic deformation in steels[J]. Scripta Materialia, 2009, 60: 1044-1049.
[10]Babu S S, Specht E D, David S A, et al. In-situ observations of lattice parameter fluctuations in austenite and transformation to bainite[J]. Metallurgical and Materials Transactions A, 2005, 36: 3281-3289.
[11]顾邦平, 胡雄, 徐冠华, 等. 基于位错密度演化的高频振动时效微观机理[J]. 稀有金属材料与工程, 2018, 47(8): 207-212.
Gu Bangping, Hu Xiong, Xu Guanhua, et al. Microcosmic mechanism of high-frequency vibratory stress relief based on dislocation density evolution[J]. Rare Metal Materials and Engineering, 2018, 47(8): 207-212.
[12]Chakraborty J, Bhattacharjee D, Manna I. Microstructural refinement of bainite and martensite for enhanced strength and toughness in high-carbon low-alloy steel[J]. Metallurgical and Materials Transactions A, 2010, 41: 2871-2878.
[13]Podder A S, Lonardelli I, Molinari A, et al. Thermal stability of retained austenite in bainitic steel: An in situ study[J]. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2011, 467: 3141-3156.
[14]Peet M. Transformation and tempering of low-temperature bainite[D]. Cambridge: University of Cambridge, 2010.
[15]Caballeroa F G, Wei Y H, Miller M K, et al. Three phase crystallography and solute distribution analysis during residual austenite decomposition in tempered nanocrystalline bainitic steels[J]. Materials Characterization, 2014, 88: 15-20.