Authors: Yong Jie Ma, Xun He, Guang Liang Zhang
Abstract: In high strength pipeline steel rolling technology, the control of final cooling temperature of different microstructure, different microstructure of pipeline steel tensile strength, yield strength and the effects of different, thus determine its yield ratio differences. The results show that with lath bainite microstructure of the pipeline steel than with acicular ferrite microstructure of the pipeline steel with lower yield ratio, at the same time lath bainite microstructure in small dispersed precipitates in pipeline steel X80 pipeline steel to reduce the yield ratio is beneficial, for high strength pipeline steel production technology to provide the theory basis.
310
Authors: Hong Wei Liu, Hong Yun Zhao, Jing Bo Yu
Abstract: Microstructure and mechanical properties of 22MnB5 Steel were analysis with different heat treatment experiment. The result show that the martensite lath with water cooling become smaller than that with metal die cooling, The lath martensitic microstructure is disappeared with die cooling & tempered specimen. The tensile strength reaches the highest 1645.34MPa by water cooling, but the plastic strength product is lowest. Q&P and die cooling & tempering process can improve the elongation of 22MnB5 with a small amount of tensile strength decrease. The plastic strength product reaches the highest of 20312.74MPa•% by die cooling & tempering method.
55
Authors: Le Yu Zhou, Tian Hao Cui, Bo Jiang, Chao Lei Zhang, Jian Zhong He, Ya Zheng Liu
Abstract: In according with the transformation rules of C-Si-Mn-Cr and C-Si-Mn-Cr-Mo tested steels, rolling experiment was carried out in lab. to analyze the effect of Mo on transformation, microstructure and property of high strength hot rolled dual phase steels. The results showed that the addition of element Mo decreased start temperature of ferrite transformation and restrains pearlite transformation. There was a metastable austenite zone between ferrite and bainite transformation zone of No.2 steel with 0.35% of Mo. After controlled rolling and step cooling process, dual phase microstructures in which fine martensite islands dispersed in soft ferrite matrix were obtained by two kinds of tested steel. With the addition of Mo, yield strength and tensile strength increased by 80MPa and 60MPa respectively, meanwhile, elongation increased slightly.
560
Authors: Zi Shan Yao, Guang Xu, Ming Xing Zhou
Abstract: Rebar steel is used in the construction of various buildings. Vanadium (V), one of microalloying elements, is often added in the rebar steel to improve mechanical property. In order to analyse the effect of V on the microstructure and property of rebar steel, 0.043 wt.% V was added in a 20MnSi rebar steel. The base steel and V added steel were refined in a 50 kg vacuum induction furnace and rolled to plates of 14 mm thick. The mechanical properties of two steels were compared by tensile tests on a Wan-10000 tensile testing machine. The microstructure and precipitation of two steels were analysed by SEM and TEM observations. The microstructures of two steels consist of ferrite and pearlite. However, the grains of V bearing steel are finer. Moreover, fine nanoscale precipitates of V can be observed in V bearing steel. Therefore, the mechanical property of V addition rebar steel is improved by gain refinement strengthening and precipitation strengthening.
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