Abstract: With the development of X65 and X70 pipeline steel, low cost and excellent mechanical properties become the target in modern industry. Due to the thermal mechanical control processing (TMCP) and ultra fast cooling (UFC) technology, the good combination of low cost and excellent mechanical properties can be realized. The microstructures and mechanical properties of low cost X65 and X70 niobium microalloyed pipeline steel were researched and trial-produced in this paper. Ultimately, the welded steel pipes were produced using the low cost X65 and X70 steels by Julong steel pipe company. The production practice and test results show that the low cost X65 and X70 pipeline steels developed by Tangsteel have excellent strength and toughness with yield strength of 566MPa, tensile strength of 627MPa, elongation of 40.8%, impact energy of 422J at -20oC, and shear area of 99% in the drop-weight tear test (DWTT) at -15oC.
Authors: Xiao-Long Yang, Qiang Wang, Shao-Jiang Yin, Miao Zang, Zhi-Xiu Zheng, Wei-Jian Liu, and Yun-Ge Wang
Keywords: X65 and X70, pipeline steel, low cost