Effect of post-rolling cooling process on microstructure of large-transmission X80M pipeline steel
LIU Gan1,2, KONG Xianglei1,2, HUANG Minghao1,2, WANG Yang1,2, ZHANG Yinghui1,2
1. State Key Laboratory of Metal Materials and Application for Marine Equipment, Anshan 114009, Liaoning, China; 2. Iron & Steel Research Institute, Ansteel Group, Anshan 114009, Liaoning, China
Abstract：In order to ensure the high strength of large-transmission X80M pipeline steel and further improve its low temperature toughness, and achieve a good match of strength and toughness, Gleeble-3800 thermal simulation tester was used to simulate rolling. The dynamic CCT curve was established by thermal expansion method combined with microstructure analysis, and the effects of cooling rate and final cooling temperature on the microstructure and hardness were studied by OM, SEM, hardness testing and other analytical methods. The results show that with the increase of cooling rate, the microstructure produces the transition of PF+P→GB→AF→BF, and the Vickers microhardness gradually increases. The ideal microstructure consisting of fine uniform AF and diffusely distributed M/A islands can be obtained when the cooling rate is in the range of 15-25 ℃/s. Final cooling temperature has an obvious effect on its phase composition. As the final cooling temperature decreases, the M/A island size becomes smaller, the number increases and its microstructure gradually refines. Combining experimental research with production practice, the final industrialized TMCP parameters are set to final rolling temperature of 780 ℃+final cooling temperature of 360 ℃+cooling speed of 20 ℃/s. The obtained X80M pipeline steel coil has high strength and excellent low temperature toughness, which meets its engineering and technical requirements, and is successfully applied in the major pipeline project of West-East Gas Transmission Line IV. This study provides technical reference for the research and development of high-strength and high-toughness pipeline steel and strongly supports the construction of national major pipeline projects.
刘干, 孔祥磊, 黄明浩, 王杨, 张英慧. 轧后冷却工艺对大输量X80M管线钢显微组织的影响[J]. 中国冶金, 2023, 33(11): 81-87.
LIU Gan, KONG Xianglei, HUANG Minghao, WANG Yang, ZHANG Yinghui. Effect of post-rolling cooling process on microstructure of large-transmission X80M pipeline steel[J]. China Metallurgy, 2023, 33(11): 81-87.
WANG W,SHAN Y Y,YANG K. Study of high strength pipeline steels with different microstructures[J]. Materials Science and Engineering A,2009,502(1/2):38.
ZHENG X F,KANG Y L,MENG D L,et al. Effect of cooling start temperature on microstructure and mechanical properties of X80 high deformability pipeline steel[J]. Journal of Iron and Steel Research International,2011,18(10):42.
[12]
WU Q,HE S,HU P,et al. Effect of finish rolling temperature on microstructure and mechanical properties of X80 pipeline steel by on-line quenching[J]. Materials Science and Engineering A,2023,862:144496.
ZENG Y,ZHU P,TONG K. Effect of microstructure on the low temperature toughness of high strength pipeline steels[J]. International Journal of Minerals Metallurgy and Materials,2015,22(3):254.
WANG B,LIAN J. Effect of microstructure on low-temperature toughness of a low carbon Nb-V-Ti microalloyed pipeline steel[J]. Materials Science and Engineering A,2014,592:50.
HUDA N,MIDAWI A R H,GIANETTO J,et al. Influence of martensite-austenite (MA) on impact toughness of X80 line pipe steels[J]. Materials Science and Engineering A,2016,662:481.
[20]
DUAN H,SHAN Y,YANG K,et al. Effect of rare earth and cooling process on microstructure and mechanical properties of an ultra-cleaned X80 pipeline steel[J]. Acta Metallurgica Sinica (English Letters),2021,34(5):639.
ROCCISANO A,NAFISI S,STALHEIMD,et al. Effect of TMCP rolling schedules on the microstructure and performance of X70 steel[J]. Materials Characterization,2021,178:111207.
[27]
ZHOU F,LI L J,GAO J X,et al. Effect of ultra fast cooling coiling temperature on microstructures and properties of X80 pipeline steel[C]//5th Annual International Conference on Material Science and Engineering (ICMSE2017). Xiamen:[s.n.],2017:012037.
2023, Vol. 33 
