Effect of normalizing temperature on microstructure and mechanical properties of G18CrMo2-6 cast steel

doi:10.13251/j.issn.0254-6051.2024.01.021

Abstract

Abstract: Effect of normalizing temperature (850-1000 ℃) on microstructure and mechanical properties of G18CrMo2-6 steel was studied. The results show that the microstructure is granular bainite composed of bainite ferrite (BF) and M-A island after normalizing at different temperatures. With the increase of normalizing temperature, the quantity and size of M-A islands decreases first and then increases, so that impact absorbed energy of the steel increases first and then decreases. When the normalizing temperature below 940 ℃, with the increase of normalizing temperature, the quantity of M-A islands decreases, C, Cr and other elements spread into BF, leading to increase yield strength. When the normalizing temperature is 940 ℃, the tensile strength and impact absorbed energy of the steel are the highest, which are 942 MPa and 28 J, respectively. When the normalizing temperature is further increased, the dislocations in BF are reduced and the grains are coarsened, resulting in a decrease in yield strength.

Key words: G18CrMo2-6 steel, normalizing temperature, granular bainite, M-A islands

CLC Number:

TG142.1

Chen Yubo, Wang Peijie, Yuan Hairui, Li Zhenjiang. Effect of normalizing temperature on microstructure and mechanical properties of G18CrMo2-6 cast steel[J]. Heat Treatment of Metals, 2024, 49(1): 137-141.

References

[1]Li Zhengjing, Xiao Namin, Li Dianzhong, et al. Effect of microstructure evolution on strength and impact toughness of G18CrMo2-6 heat-resistant steel during tempering[J]. Materials Science and Engineering A, 2014, 604: 103-110.
[2]李云良, 张汉谦, 彭碧草, 等. 核电压力容器用钢的发展及研究现状[J]. 压力容器, 2010, 27(5): 36-43.
Li Yunliang, Zhang Hanqian, Peng Bicao, et al. Development and recent research of nuclear reactor pressure vessel steels[J]. Pressure Vessel Technology, 2010, 27(5): 36-43.
[3]Dai Xin, Peng Tao, Chen Yuefeng, et al. The correlation between martensite-austenite islands evolution and fatigue behavior of SA508-IV steel[J]. International Journal of Fatigue, 2020, 139: 105776.
[4]Luo Yi, Peng Jinmin, Wang Hongbin, et al. Effect of tempering on microstructure and mechanical properties of a non-quenched bainitic steel[J]. Materials Science and Engineering A, 2010, 527(15): 3433-3437.
[5]Liu Dongyu, Bai Bingzhe, Fang Hongsheng, et al. Effect of tempering temperature and carbide free bainite on the mechanical characteristics of a high strength low alloy steel[J]. Materials Science and Engineering A, 2004, 371(1/2): 40-44.
[6]蒋中华, 杜军毅, 王培, 等. M-A岛高温回火转变产物对核电SA508-3钢冲击韧性影响机制[J]. 金属学报, 2021, 57(7): 891-902.
Jiang Zhonghua, Du Junyi, Wang Pei, et al. Mechanism of improving the impact toughness of SA508-3 steel used for nuclear power by pre-transformation of M-A islands[J]. Acta Metallurgica Sinica, 2021, 57(7): 891-902.
[7]蒋中华, 王培, 李殿中, 等. 回火温度对2.25Cr-1Mo-0.25V钢粒状贝氏体显微组织和力学性能的影响[J]. 金属学报, 2015, 51(8): 925-934.
Jiang Zhonghua, Wang Pei, Li Dianzhong, et al. Effects of tempering temperature on the microstructure and mechanical properties of granular bainite in 2.25Cr-1Mo-0.25V steel[J]. Acta Metallurgica Sinica, 2015, 51(8): 925-934.
[8]Wang Yu, Xu Yunbo, Zhang Tianyu, et al. Effects of quenching temperature on bainite transformation, retained austenite and mechanical properties of hot-galvanized Q&P steel[J]. Materials Science and Engineering A, 2021, 822: 141643.
[9]Li Jiayu, Xu Yunbo, Lu Bing, et al. Improvement of strength-ductility combination in ultra-high-strength medium-Mn Q&P steel by tailoring the characteristics of martensite/retained austenite constituents[J]. Journal of Materials Research and Technology, 2022, 18: 352-369.
[10]Dong X X, Shen Y F. Improving mechanical properties and corrosion resistance of 0.5wt.%C TRIP steel by adjusting retained austenite stability and microstructural constituents[J]. Materials Science and Engineering A, 2022, 852: 143737.
[11]Ramachandran D C, Moon J, Lee C H, et al. Role of bainitic microstructures with M-A constituent on the toughness of an HSLA steel for seismic resistant structural applications[J]. Materials Science and Engineering A, 2021, 801: 140390.
[12]Bansal G K, Tripathy S, Chandan A K, et al. Influence of quenching strategy on phase transformation and mechanical properties of low alloy steel[J]. Materials Science and Engineering A, 2021, 826: 141937.
[13]石丽辉, 徐萌波. 正火对建筑用热轧20MnV钢组织与性能的影响[J]. 金属热处理, 2019, 44(7): 28-33.
Shi Lihui, Xu Mengbo. Effect of normalizing on microstructure and properties of hot rolled 20MnV steel for construction[J]. Heat Treatment of Metals, 2019, 44(7): 28-33.
[14]程晔锋, 程巨强, 冯熠婷. 正火温度对高强度贝氏体钢管组织和性能的影响[J]. 西安工业大学学报, 2020, 40(4): 428-433.
Cheng Yefeng, Cheng Juqiang, Feng Yiting. Effects of normalizing temperature on microstructure and properties of high strength bainitic steel pipe[J]. Journal of Xi'an Technological University, 2020, 40(4): 428-433.
[15]冯丹竹, 隋轶, 张宏亮, 等. 正火工艺对12Cr1MoV合金结构钢组织性能的影响[J]. 宽厚板, 2022, 28(1): 1-5.
Feng Danzhu, Sui Yi, Zhang Hongliang, et al. Effects of normalizing process on microstructure and properties of 12Cr1MoV alloy structural steel[J]. Wide and Heavy Plate, 2022, 28(1): 1-5.
[16]王小勇, 潘涛, 王华, 等. Ni-Cr-Mo-B超厚钢板表面低碳回火马氏体组织的韧性研究[J]. 金属学报, 2012, 48(4): 401-406.
Wang Xiaoyong, Pan Tao, Wang Hua, et al. Investigation of the toughness of low carbon tempered martensite in the surface of Ni-Cr-Mo-B ultra-heavy plate steel[J]. Acta Metallurgica Sinica, 2012, 48(4): 401-406.
[17]Li Zhenjiang, Liu Yujing, Zhang Ruyi, et al. Study on impact fracture behavior of G18CrMo2-6 steel after tempering[J]. Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications, 2021, 235(11): 2627-2636.
[18]王云龙, 余伟, 张昳, 等. 奥氏体化温度对贝氏体钢等温转变及力学性能的影响[J]. 金属热处理, 2022, 47(4): 80-85.
Wang Yunlong, Yu Wei, Zhang Yi, et al. Effect of austenitizing temperature on isothermal transformation and mechanical properties of bainite steel[J]. Heat Treatment of Metals, 2022, 47(4): 80-85.
[19]Zhou S B, Hu F, Zhou W, et al. Effect of retained austenite on impact toughness and fracture behavior of medium carbon submicron-structured bainitic steel[J]. Journal of Materials Research and Technology, 2021, 14: 1021-1034.
[20]熊国源, 刘利华, 朱文涛. 奥氏体化温度对40CrNiMo钢组织和性能的影响[J]. 中国冶金, 2021, 31(7): 30-37.
Xiong Guoyuan, Liu Lihua, Zhu Wentao. Effect of austenitizing temperature on microstructure and mechanical properties of 40CrNiMo steel[J]. China Metallurgy, 2021, 31(7): 30-37.