Effect of Nb content on continuous cooling transformation rule, microstructure and properties of V-Ti-N structural steel

doi:10.13251/j.issn.0254-6051.2024.03.039

Abstract

Abstract: Continuous cooling transformation curves of the Nb-V-Ti-N microalloyed steels were conducted on a DIL-805 dilatometer, and the effect of Nb content on the microstructure and properties was investigated. The results show that when the cooling rate increases from 0.1 ℃/s to 30 ℃/s, the undercooled austenite successively transforms into ferrite, pearlite, bainite and martensite, and the corresponding cooling rate ranges are 0.1-20, 0.1-5, 1-30 and 10-30 ℃/s, respectively. The transformation temperatures of ferrite, pearlite and bainite decrease with the increase of cooling rate, while that of martensite increases. As the Nb content increases from 0.05% to 0.10%, the solid solution of Nb in austenite increases, the CCT curves are slightly downward, and both Ac₁ and Ac₃ temperatures increase. With the increase of cooling rate, the microhardness is enhanced, and the corresponding value in the range of 1-20 ℃/s for the tested steel containing 0.10%Nb is higher than that for the steel with 0.05%Nb, which is largely related to the percentage of hardening phases, the degree of microstructure refinement and the precipitation of carbonitrides. In addition, the submicron Nb-rich carbonitrides precipitated at the high temperature region of austenite can not only pin grain boundaries but also act as heterogeneous nucleation sites to induce the formation of intragranular ferrite, which effectively refine the microstructure and consequently improve the strength and toughness.

Key words: Nb-V-Ti-N microalloyed steel, continuous cooling transformation curves, Nb content, microstructural evolution, microhardness

CLC Number:

TG142.3

Tong Yang, Zhang Jing, Xin Wenbin, Luo Guoping, Peng Jun, Hou Dengyun. Effect of Nb content on continuous cooling transformation rule, microstructure and properties of V-Ti-N structural steel[J]. Heat Treatment of Metals, 2024, 49(3): 236-243.

References

[1]易伦雄, 高宗余, 陈维雄. 沪通长江大桥高性能结构钢的研发与应用[J]. 桥梁建设, 2015, 45(6): 36-40.
Yi Lunxiong, Gao Zongyu, Chen Weixiong. Development and application of high-performance structural steel for Hutong Changjiang River Bridge[J]. Bridge Construction, 2015, 45(6): 36-40.
[2]黄维, 高真凤, 张志勤. 日本建筑结构用钢板发展现状[J]. 建筑钢结构进展, 2015, 17(1): 1-6.
Huang Wei, Gao Zhenfeng, Zhang Zhiqin. Development status of steel plate for building structures in Japan[J]. Progress in Steel Building Structures, 2015, 17(1): 1-6.
[3]张圣柱, 程玉峰, 冯晓东, 等. X80管线钢性能特征及技术挑战[J]. 油气储运, 2019, 38(5): 481-495.
Zhang Shengzhu, Cheng Yufeng, Feng Xiaodong, et al. Performance characteristics and technical challenges of X80 pipeline steel[J]. Oil and Gas Storage and Transportation, 2019, 38(5): 481-495.
[4]何建中. 钢结构用钢及钢结构产品的发展与应用[J]. 包钢科技, 2018, 44(3): 1-8.
He Jianzhong. Development and application of steel for steel structure and steel structure products[J]. Science and Technology of Baotou Steel, 2018, 44(3): 1-8.
[5]罗海文, 沈国慧. 超高强高韧化钢的研究进展和展望[J]. 金属学报, 2020, 56(4): 494-512.
Luo Haiwen, Shen Guohui. Progress and perspective of ultra-high strength steels having high toughness[J]. Acta Metallurgica Sinica, 2020, 56(4): 494-512.
[6]李麟. 汽车用高强钢的发展与展望[J]. 上海金属, 2022, 44(3): 1-8.
Li Lin. Development and prospect of high strength steel for automobile[J]. Shanghai Metals, 2022, 44(3): 1-8.
[7]Misra R D K, Nathani H, Hartmann J E. Microstructural evolution in a new 770 MPa hot rolled Nb-Ti microalloyed steel[J]. Materials Science and Engineering A, 2005, 394(1): 339-352.
[8]Rodrigues P C M, Pereloma E V, Santos D B. Mechanical properties of an HSLA bainitic steel subjected to controlled rolling with accelerated cooling[J]. Materials Science and Engineering A, 2000, 283(1): 136-143.
[9]李小琳, 王昭东, 邓想涛, 等. 超快冷终冷温度对含Nb-V-Ti微合金钢组织转变及析出行为的影响[J]. 金属学报, 2015, 51(7): 784-790.
Li Xiaolin, Wang Zhaodong, Deng Xiangtao, et al. Effect of final temperature after ultra-fast cooling on microstructural evolution and precipitation behavior of Nb-V-Ti bearing low alloy steel[J]. Acta Metallurgica Sinica, 2015, 51(7): 784-790.
[10]Hu J, Du L X, Dong Y, et al. Effect of Ti variation on microstructure evolution and mechanical properties of low carbon medium Mn heavy plate steel[J]. Materials Characterization, 2019, 152: 21-35.
[11]Wen X L, Mei Z, Jiang B, et al. Effect of normalizing temperature on microstructure and mechanical properties of a Nb-V microalloyed large forging steel[J]. Materials Science and Engineering A, 2016, 671: 233-243.
[12]Zhang J, Wang F M, Yang Z B, et al. Effect of cooling rate on precipitation behavior and micromechanical properties of ferrite in V-N alloyed steel during a simulated thermomechanical process[J]. Metallurgical and Materials Transactions A, 2017, 48: 6142-6152.
[13]杨才福. 钒微合金化钢的技术进展与应用[J]. 钢铁研究学报, 2020, 32(12): 1029-1043.
Yang Caifu. Recent development and applications vanadium microalloying technology[J]. Journal of Iron and Steel Research, 2020, 32(12): 1029-1043.
[14]崔辰硕. V-N微合金钢贝氏体区析出行为及组织性能研究[D]. 沈阳: 东北大学, 2015.
[15]Huang H H, Yang G W, Zhao G, et al. Effect of Nb on the microstructure and properties of Ti-Mo microalloyed high-strength ferritic steel[J]. Materials Science and Engineering A, 2018, 736: 148-155.
[16]Zhang D Q, Liu G, Zhang K, et al. Effect of Nb microalloying on microstructure evolution and mechanical properties in low carbon medium manganese steel[J]. Materials Science and Engineering A, 2021, 824: 141813.
[17]El-Shenawy E, Reda R. Optimization of TMCP strategy for microstructure refinement and flow-productivity characteristics enhancement of low carbon steel[J]. Journal of Materials Research and Technology, 2019, 8: 2819-2831.
[18]Anatoliy Z, Valeriy P, Thierry B, et al. Effect of heat treatment on the mechanical properties and microstructure of HSLA steels processed by various technologies[J]. Materials Today Communications, 2021, 28: 102598.
[19]Roccisano A, Nafisi S, Stalheim D, et al. Effect of TMCP rolling schedules on the microstructure and performance of X70 steel[J]. Materials Characterization, 2021, 178: 111207.
[20]张金城, 孙胜辉, 蔡明晖, 等. 控轧控冷对Ti-Mo-Nb复合微合金化低碳钢组织和力学性能的影响[J]. 金属热处理, 2023, 48(1): 155-162.
Zhang Jincheng, Sun Shenghui, Cai Minghui, et al. Effect of TMCP on microstructure and mechanical properties of Ti-Mo-Nb microalloyed low carbon steel[J]. Heat Treatment of Metals, 2023, 48(1): 155-162.
[21]徐洋. 钛微合金化钢中铁素体相变及纳米相析出行为与机理研究[D]. 沈阳: 东北大学, 2015.
[22]王权, 孙婷婷, 白雅琼. 冷却速度对超低碳微合金钢组织和性能的影响[J]. 金属热处理, 2015, 40(2): 148-151.
Wang Quan, Sun Tingting, Bai Yaqiong. Effect of cooling rate on microstructure and mechanical properties of ultra-low carbon micro-alloyed steel[J]. Heat Treatment of Metals, 2015, 40(2): 148-151.
[23]何博, 彭天恩, 胡学文, 等. Nb对高Ti耐候钢连续冷却后显微组织及硬度的影响[J]. 金属热处理, 2022, 47(8): 46-51.
He Bo, Peng Tianen, Hu Xuewen, et al. Effect of Nb on microstructure and hardness of high Ti weathering steel after continuous cooling[J]. Heat Treatment of Metals, 2022, 47(8): 46-51.
[24]张可, 李昭东, 隋凤利, 等. 冷却速率对Ti-V-Mo复合微合金钢组织转变及力学性能的影响[J]. 金属学报, 2018, 54(1): 31-38.
Zhang Ke, Li Zhaodong, Sui Fengli, et al. Effect of cooling rate on microstructure evolution and mechanical properties of Ti-V-Mo complex microalloyed steel[J]. Acta Metallurgica Sinica, 2018, 54(1): 31-38.
[25]葛紫薇, 张婧, 辛文彬, 等. Nb-V-Ti-N微合金化结构钢中碳氮化物析出的热力学分析与试验研究[J]. 稀有金属与硬质合金, 2022, 50(3): 57-64, 71.
Ge Ziwei, Zhang Jing, Xing Wenbin, et al. Thermodynamic analysis and experimental study on precipitation of carbonitrides in Nb-V-Ti-N microalloyed structural steel[J]. Rare Metals and Cemented Carbides, 2022, 50(3): 57-64, 71.
[26]张婧. 600 MPa级高强钢筋用钢成分与控冷工艺的研究[D]. 北京: 北京科技大学, 2016.
[27]Miranda R S, Rezende A B, Fonseca S T, et al. Fatigue and wear behavior of pearlitic and bainitic microstructures with the same chemical composition and hardness using twin-disc tests[J]. Wear, 2022, 494-495: 204253.