Study on the Quality of Wide and Thick X80 Pipeline Steel Billet
Author of the article:GAO Yan;JIANG Jinxing;ZUO Xiurong;JI Yinglun;WANG Huihui
Author's Workplace：Nanjing Iron and Steel Co., Ltd., Nanjing 210035, China;Key Laboratory of Material Physics, Ministry of Education,Zhengzhou University, Zhengzhou 450052, China
Key Words：X80 pipeline steel continuous casting slab segregation white band microstructure hardness
Abstract：
Chemical composition, microstructure and hardness of the slab with the change of thickness were studied by inductively coupled plasma-atomic(optical) emission spectrometry, metallographic microscopy and microhardness tester.Research shows that negative segregation was produced in white band layer, resulting obvious decrease in hardness.Positive segregation layer of C and Ni was located above white band layers in inner arc, and negative segregation layer of C and Ni was located below white band layers. The internal segregation is not serious. Si, Mn, Cr, Cu, Mo and Nb distributed homogeneously in thickness direction. Standard deviation of hardness in billet center was higher than other location. The billet center was the final solidification zone, cooling rate decrease in this zone resulted coarse grains.Positive segregation layer of C and Ni located above white band layers in inner arc resulted the highest hardness in thickness direction.
