Effect of cooling temperature on microstructure and mechanical properties of a hot-rolled dual-phase steel

doi:10.13251/j.issn.0254-6051.2025.01.033

Abstract

Abstract: Based on the process of thin slab continuous casting and rolling, the effect of various cooling temperatures after hot rolling on the microstructure and properties of a hot-rolled dual-phase steel was studied by using optical microscope, universal tensile machine, microhardness tester, and X-ray diffractometer. The results show that the yield strength and tensile strength first decrease and then increase, while the total elongation gradually decreases with the cooling temperature increases from 640 ℃ to 720 ℃. In addition, the hardness decreases first and then increases with the increase of cooling temperature, which is consistent with the trend of strength changes, indicating that higher strength and hardness can be obtained after cooling at 720 ℃. The grain size of ferrite first increases and then decreases with the increase of increasing cooling temperature, and the martensite content gradually increases. It is shown from the calculation according to the strengthening mechanism of the dual-phase steel that the difference in strength of the specimens under different cooling temperatures is mainly due to the differences in grain refinement strengthening, transformation strengthening and dislocation strengthening, among which the grain refinement strengthening and dislocation strengthening are the main mechanisms, and the theoretical strength calculation results are in agreement with the experimental results.

Key words: dual-phase steel, cooling temperature, microstructure, mechanical properties, strengthening mechanism

CLC Number:

TG142.1

Wang Cheng, Liu Yajun, Chen Zhihui, Tong Shankang, Gan Xiaolong. Effect of cooling temperature on microstructure and mechanical properties of a hot-rolled dual-phase steel[J]. Heat Treatment of Metals, 2025, 50(1): 213-218.

References

[1]Liu Yajun, Gan Xiaolong, Wang Shuize, et al. Effect of coiling temperature on microstructure and properties of a Ti-Nb microalloyed high speed guardrail steel[J]. Steel Research International, 2023, 94: 2200840.
[2]Liu B, Wu R, Hu J. Effect of cooling process on mechanical properties of thin-gauge hot-rolled dual-phase steel[C]//IOP Conference Series: Materials Science and Engineering. IOP Publishing, 2019, 474(1): 012020.
[3]Li Zhuang, Wu Di, Lü Wei, et al. Effect of holding time on the microstructure and mechanical properties of dual-phase steel during intercritical annealing[J]. Journal of Wuhan University of Technolog, 2015, 30: 156-161.
[4]颜文超, 高波, 肖礼容, 等. 温轧和临界退火制备超细晶异构双相钢的微观结构及力学性能[J]. 金属热处理, 2024, 49(7): 54-62.
Yan Wenchao, Gao Bo, Xiao Lirong, et al. Microstructure and mechanical properties of ultrafine grained heterostructured dual-phase steel prepared by warm rolling and intercritical annealing[J]. Heat Treatment of Metals, 2024, 49(7): 54-62.
[5]薛峰, 耿志宇, 刘旭明, 等. 高强双相钢DP980成形极限性能及微观组织分析[J]. 金属热处理, 2024, 49(6): 164-168.
Xue Feng, Geng Zhiyu, Liu Xuming, et al. Forming limit properties and microstructure analysis of high strength dual phase steel DP980[J]. Heat Treatment of Metals, 2024, 49(6): 164-168.
[6]张家豪, 陈连生, 高天洋, 等. 过时效温度对连续退火制备DP1180钢组织性能的影响[J]. 金属热处理, 2023, 48(1): 149-154.
Zhang Jiahao, Chen Liansheng, Gao Tianyang, et al. Effect of over-aging temperature on microstructure and properties of DP1180 steel under continuous annealing process[J]. Heat Treatment of Metals, 2023, 48(1): 149-154.
[7]杨灿, 校振华, 冯启生, 等. 高强汽车双相钢的连续退火与组织性能研究[J]. 精密成形工程, 2023, 15(10): 168-176.
Yang Can, Jiao Zhenhua, Feng Qisheng, et al. Research on continuous annealing and microstructure and properties of high strength automotive dual phase steel[J]. Precision Forming Engineering, 2023, 15(10): 168-176.
[8]Wang Zhigang, Zhao Aimin, Zhao Zhengzhi, et al. Microstructures and mechanical properties of C-Mn-Cr-Nb and C-Mn-Si-Nb ultra-high strength dual-phase steels[J]. International Journal of Minerals, Metallurgy, and Materials, 2012, 19(10): 915-922.
[9]Sayed A A, Kheirandish S. Effect of the tempering temperature on the microstructure and mechanical properties of dual phase steels[J]. Materials Science and Engineering A, 2012, 532: 21-25.
[10]Jamei F, Mirzadeh H, Zamani M. Synergistic effects of holding time atintercritical annealing temperature and initial microstructure on the mechanical properties of dual phase steel[J]. Materials Science and Engineering A, 2019, 750: 125-131.
[11]徐勇, 段星宇, 曾祥成, 等. 不同应变速率下DP980双相钢微观组织特征及变形机制[J]. 钢铁研究学报, 2023, 35(5): 595-604.
Xu Yong, Duan Xingyu, Zeng Xiangcheng, et al. Microstructural characteristics and deformation mechanism of DP980 dual phase steel under different strain rates[J]. Journal of Iron and Steel Research, 2023, 35(5): 595-604.
[12]杨海根, 喻进安. 热轧双相钢的轧制工艺研究[J]. 金属世界, 2009(1): 46-50.
Yang Haigen, Yu Jin'an. Research on rolling process of hot rolled dual phase steel[J]. Metal World, 2009(1): 46-50.
[13]Liu Yajun, Gan Xiaolong, Liang Wen, et al. Microstructure evolution and mechanical response of a direct quenched and partitioned steel at different finishing rolling temperatures[J]. Materials, 2023, 16(9): 3575.
[14]Karam-abian M, Zarei-hanzaki A, Abedi H R, et al. Micro and macro-mechanical behavior of a transformation-induced plasticity steel developed by thermomechanical processing followed by quenching and partitioning[J]. Materials Science and Engineering A, 2016, 651: 233-240.
[15]Williamson G K, Hall W H. X-ray line broadening from filed aluminium and wolfram[J]. Acta Metallurgica, 1953, 1(1): 22-31.
[16]Williamson G K, Smallman R E. III. Dislocation densities in some annealed and cold-worked metals from measurements on the X-ray debye-scherrer spectrum[J]. Philosophical Magazine, 1956, 1(1): 34-46.
[17]Cai Feng, Zhou Mingxing, Tian Junyu, et al. Comparative study of the role of niobium in low-carbon ferritic and bainitic steels[J]. Materials Science and Engineering A, 2022, 851: 143579.
[18]张志强, 刘洪旭, 李鑫, 等. 冷却工艺对DP700热轧双相钢组织及性能的影响[J]. 钢铁研究学报, 2022, 34(12): 1457-1464.
Zhang Zhiqiang, Liu Hongxu, Li Xin, et al. The effect of cooling process on the microstructure and properties of DP700 hot-rolled dual phase steel[J]. Journal of Iron and Steel Research, 2022, 34(12): 1457-1464.
[19]董毅, 韩斌, 时晓光, 等. 冷却工艺对Si-Mn系热轧双相钢组织和性能的影响[J]. 钢铁, 2011, 46(10): 66-69, 74.
Dong Yi, Han Bin, Shi Xiaoguang, et al. The effect of cooling process on the microstructure and properties of Si-Mn hot-rolled dual phase steel[J]. Iron and Steel, 2011, 46(10): 66-69, 74.
[20]刘斌, 王志刚, 王孟, 等. 冷却工艺对高强度热轧双相钢组织与力学性能的影响[J]. 热加工工艺, 2017, 46(17): 174-176.
Liu Bin, Wang Zhigang, Wang Meng, et al. The effect of cooling process on the microstructure and mechanical properties of high-strength hot-rolled dual phase steel[J]. Hot Working Technology, 2017, 46(17): 174-176.
[21]轧制技术及连轧自动化国家重点试验室(东北大学). 热轧双相钢先进生产工艺研究与开发[M]. 北京: 冶金工业出版社, 2015.
State Key Laboratory of Rolling Technology and Continuous Rolling Automation (Northeastern University). Research and Development of Advanced Production Process of Hot Rolled Dual Phase Steel[M]. Beijing: Metallurgical Industry Press, 2015.
[22]Grange R A, Hribal C R, Porter L F. Hardness of tempered martensite in carbon and low-alloy steels[J]. Metallurgical Transactions A (Physical Metallurgy and Materials, Science), 1977, 8(11): 1775-1785.
[23]Pickering F B. Physical Metallurgy and the Design of Steels[M]. Applied Science Publishing, 1978.
[24]陈良, 张超, 朱帅, 等. CSP线生产薄规格超高强带钢的轧制工艺与组织性能[J]. 钢铁, 2014, 49(1): 57-61.
Chen Liang, Zhang Chao, Zhu Shuai, et al. Rolling process and microstructure properties of thin specification ultra-high strength strip produced by CSP line[J]. Iron and Steel, 2014, 49(1): 57-61.
[25]温东辉. 金相组织对双相钢强度影响的研究[J]. 上海金属, 2005, 27(6): 51-55.
Wen Donghui. Study on the influence of metallographic structure on the strength of duplex steel[J]. Shanghai Metal, 2005, 27(6): 51-55.