Effective Microstructure Unit in Control of Impact Toughness in CGHAZ for High Strength Bridge Steel
来源期刊：Journal Of Wuhan University Of Technology Materials Science Edition2018年第1期
论文作者：杨秀芝 张李超 史玉升 YU Shengfu DONG Chunfa HUA Wenlin LI Xuan
文章页码：177 - 184
摘 要：The high strength bridge steel was processed with the simulated coarse grain heat affected zone(CGHAZ) thermal cycle with heat input varying from 30 to 60 kJ/cm, the microstructures were investigated by means of optical microscope(OM), scanning electron microscope(SEM), electron backscattering diffraction(EBSD) and transmission electron microscope(TEM), and the impact properties were evaluated from the welding thermal cycle treated samples. The results indicate that the microstructure is primarily composed of lath bainite. With decreasing heat input, both bainite packet and block are significantly refined, and the toughness has an increasing tendency due to the grain refinement. The fracture surfaces all present cleavage or fracture for the samples with different heat inputs. Moreover, the average cleavage facet size for the CGHAZ is nearly equal to the average bainite packet size and the bainitic packet boundary can strongly impede the crack propagation, indicating that the bainitic packet is the most effective unit in control of impact toughness in the simulated CGHAZ of high strength bridge steel.
杨秀芝1,2，张李超1，史玉升1，YU Shengfu1，DONG Chunfa2，HUA Wenlin2，LI Xuan3
1. State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology2. Institute of Mechanical Engineering, Hubei Polytechnic University3. Institute of Mechanical Engineering, Wuhan Textile University
摘 要：The high strength bridge steel was processed with the simulated coarse grain heat affected zone(CGHAZ) thermal cycle with heat input varying from 30 to 60 kJ/cm, the microstructures were investigated by means of optical microscope(OM), scanning electron microscope(SEM), electron backscattering diffraction(EBSD) and transmission electron microscope(TEM), and the impact properties were evaluated from the welding thermal cycle treated samples. The results indicate that the microstructure is primarily composed of lath bainite. With decreasing heat input, both bainite packet and block are significantly refined, and the toughness has an increasing tendency due to the grain refinement. The fracture surfaces all present cleavage or fracture for the samples with different heat inputs. Moreover, the average cleavage facet size for the CGHAZ is nearly equal to the average bainite packet size and the bainitic packet boundary can strongly impede the crack propagation, indicating that the bainitic packet is the most effective unit in control of impact toughness in the simulated CGHAZ of high strength bridge steel.
关键词：
