Direct-quenching and tempering process and microstructure-property of ultra-high strength steel for construction machinery

doi:10.13251/j.issn.0254-6051.2025.03.008

Abstract

Abstract: Effects of cooling rate (2-20 ℃/s) after hot deformation at 830 ℃ and tempering temperature (150-600 ℃) on the microstructure and hardness of direct-quenched ultra-high strength steel for construction machinery were studied by MMS-200 thermomechanical simulator, optical microscope(OM), scanning electron microscope(SEM) and Vickers hardness tester, and the microstructure and hardness of the steel under direct quenching and tempering process were compared with that under reheated quenching and tempering process. The results show that granular bainite and upper bainite disappear and the content of auto-tempered martensite decreases with the increase of cooling rate after hot deformation, and the microstructure is a mixture of lath martensite and auto-tempered martensite when the cooling rate exceeds 5 ℃/s. As the cooling rate increases, the hardness of the tested steel gradually increases, and the maximum hardness is 509 HV at the cooling rate of 20 ℃/s. When the tested steel is directly quenched and tempered, with the increase of tempering temperature, the precipitation position of carbides transits from the inside of martensite lath to the prior austenite grain and martensite lath boundaries, and the carbides continuously aggregate and coarsen. The hardness of the tested steel decreases with the increase of tempering temperature, and the maximum hardness is 510 HV at the tempering temperature of 150 ℃. Compared with reheated quenched and tempered steel, the width of martensite lath in direct quenched and tempered steel is smaller, and the hardness of matrix is higher under the same tempering process.

Key words: ultra-high strength steel for construction machinery, cooling rate, direct quenching, tempering temperature, microstructure

CLC Number:

TG113.25⁺1

Zheng Dongsheng, Fan Caihe, Zhou Shunzhi, Dong Yue, Xia Yi. Direct-quenching and tempering process and microstructure-property of ultra-high strength steel for construction machinery[J]. Heat Treatment of Metals, 2025, 50(3): 51-56.

References

[1] Ali M, Alatarvas T, Komi J, et al. Impact of niobium addition and non-metallic inclusions' characteristics on the microstructure and mechanical properties of low-carbon CrNiMnMoB ultrahigh-strength steel: A comprehensive investigation[J]. Journal of Materials Research and Technology, 2024, 30: 6133-6153.
[2] Keranen L, Nousiainen O, Javaheri V, et al. Mechanical properties of welded ultrahigh-strength S960 steel at low and elevated temperatures[J]. Journal of Constructional Steel Research, 2022, 198(2): 107517.
[3] Mandal A, Karmakar A, Chakrabarti D, et al. Effect of alloying and coiling temperature on the microstructure and bending performance of ultra-high-strength strip steel[J]. Metallurgical and Materials Transactions A, 2018, 49(12): 6359-6374.
[4] Suikkanen P P, Kömi J I. Microstructure, properties and design of direct quenched structural steels[J]. Materials Science Forum, 2014, 783-786: 246-251.
[5] 高朋, 高野, 陈俊, 等. 回火温度对DQ工艺1000 MPa级高强钢组织及性能的影响[J]. 金属热处理, 2019, 44(10): 72-76.
Gao Peng, Gao Ye, Chen Jun, et al. Effect of tempering temperature on microstructure and properties of 1000 MPa high strength steel produced by DQ process[J]. Heat Treatment of Metals, 2019, 44(10): 72-76.
[6] 马长文, 狄国标, 王凯凯, 等. 在线淬火对高强度钢板组织转变及力学性能的影响[J]. 机械工程材料, 2021, 45(5): 34-38.
Ma Changwen, Di Guobiao, Wang Kaikai, et al. Effect of on-line quenching on microstructure transition and mechanical properties of high-strength steel plate[J]. Materials for Mechanical Engineering, 2021, 45(5): 34-38.
[7] 杨雄. 直接淬火960 MPa级高强钢板的组织性能与板形控制研究[D]. 北京: 北京科技大学, 2021.
Yang Xiong. Research study on microstructure and shape control of directly quenched 960 MPa grade high strength steel plate[D]. Beijing: University of Science and Technology Beijing, 2021.
[8] Klein M, Rauch R, Spindler H, et al. Ultra high strength steels produced by thermomechanical hot rolling-advanced properties and applications[J]. Berg-und Hüttenmännische Monatshefte, 2012, 157(3): 108-112.
[9] Saastamoinen A, Kaijalainen A, Heikkal J, et al. The effect of tempering temperature on microstructure, mechanical properties and bendability of direct-quenched low-alloy strip steel[J]. Materials Science and Engineering A, 2018, 730: 284-294.
[10] Esterl R, Sonnleitner M, Weißensteiner I, et al. Influence of quenching conditions on texture and mechanical properties of ultra-high-strength steels[J]. Journal of Materials Science, 2019, 54: 12875-12886.
[11] Huang J M, Li L J, Luo Z C, et al. Improving the ductility of ultrahigh strength lath martensite through heterogeneous carbon distribution[J]. Journal of Materials Research and Technology, 2023, 27: 8209-8215.
[12] Ning D, Dai C R, Wu J L, et al. Carbide precipitation and coarsening kinetics in low carbon and low alloy steel during quenching and subsequently tempering[J]. Materials Characterization, 2021, 176: 111111.

[1]	Li Shenao, Chen Siwen, Niu Hongwei, Zhu Hongqian, Kan Yun, Jiang Yan, Wang Jian, Zhao Hongyun. Influence of rolling temperature on microstructure and mechanical properties of Sc microalloyed Al-3.2Cu-1.5Li alloy [J]. Heat Treatment of Metals, 2025, 50(3): 1-8.
[2]	Yan Lipeng, Sun Ruixue, Ma Bingxin, Fu Jing, Su Guang, Li Quanan, Zheng Hongjiang. Effect of aging on microstructure and properties of hot-extruded Mg-Gd-Y-Sm-Zr alloy [J]. Heat Treatment of Metals, 2025, 50(3): 9-15.
[3]	Wang Chang, Wang Liang, Zhou Peishan, Shen Wenzhu, Wang Bin. Influence of cold deformation and heat treatment on microstructure and properties of GH738 nickel-based alloy [J]. Heat Treatment of Metals, 2025, 50(3): 25-31.
[4]	Wang Guang, Yin Tianqing, Sun Yasong, Wang Xin, Ke Hanzhang, Xi Qiuyan, Hao Chen, Li Zizhou. Effect of quenching temperature on microstructure and hardness of 403 martensitic stainless steel [J]. Heat Treatment of Metals, 2025, 50(3): 57-63.
[5]	Xu Helin, Wang Jianghua. Effect of post weld heat treatment on microstructure and properties of repair welded joints of 4Cr5MoSiV die steel [J]. Heat Treatment of Metals, 2025, 50(3): 64-68.
[6]	Wang Jiaojiao, Gao Yunzhe, Guo Taiyu, Hou Wei, Zhou Yuqing, Ren Kepiao, Zhao Linlin, Zhang Ziyue. Effect of tempering time on microstructure and properties of steel used for deep well tubing [J]. Heat Treatment of Metals, 2025, 50(3): 102-106.
[7]	Wang Weiyi, Pan Yingjun, Zhou Naipeng, Chai Feng, Luo Xiaobing. Effect of direct quenching on microstructure evolution and mechanical properties of a 590 MPa Cu-bearing HSLA steel [J]. Heat Treatment of Metals, 2025, 50(3): 118-124.
[8]	Sun Jiangbo, Duan Luzhao, Ren Shuai, Sun Caifeng, Gao Zhixin, Peng Fei. Effect of heat treatment process on microstructure and hardness of 20CrMoH steel gear forgings [J]. Heat Treatment of Metals, 2025, 50(3): 143-146.
[9]	Mao Fuxiang, Yue Qi, Wang Qi, Li Peng, Zhang Jianguo. Effect of solution and aging treatment on microstructure and properties of high chromium alloy 3J40 [J]. Heat Treatment of Metals, 2025, 50(3): 147-149.
[10]	Qi Jianbo, Yang Lilin, Zhang Xudong, Jin Zili, Yu Huimin. Effect of Ce on normalizing microstructure and texture of 50W400 non-oriented silicon steel [J]. Heat Treatment of Metals, 2025, 50(3): 167-173.
[11]	Ma Ruoxi, Yin Yubin, Deng Chao, Li Ziyu, Zhang Zhelin, Ding Hua. Microstructure, mechanical properties and deformation mechanism of Fe-18Mn-8Al-1C lightweight steel [J]. Heat Treatment of Metals, 2025, 50(3): 183-188.
[12]	Zhou Hao, Du Haojie, Zeng Yanping, Guo Derui, Li Weili, Ma Zhibao, Wang Qingfeng, Li Jingxin. Microstructure and mechanical properties of long-term high temperature serviced superalloy GH4145 bolt [J]. Heat Treatment of Metals, 2025, 50(3): 189-195.
[13]	Liang Xiaodong, Wang Wei, Li Yongqing, Yuan Bo, Guo Xiaofeng, Cheng Yanlong. Microstructure and mechanical properties of G115 steel large-diameter thick-walled tube during long-term aging [J]. Heat Treatment of Metals, 2025, 50(3): 196-200.
[14]	Dong Entao, Teng Aijun, Fang Qiang, Chen Xin, Dai Guanglin, Kang Qiang, Wang Peng, Geng Naitao. Hot deformation behavior and microstructure evolution of Ti-38644 titanium alloy [J]. Heat Treatment of Metals, 2025, 50(3): 201-207.
[15]	Qi Jiasheng, Xu Wenquan. Research status and prospects of medium manganese steels for automobiles [J]. Heat Treatment of Metals, 2025, 50(3): 244-249.