Effect of Post-weld Heat Treatment Temperature on Microstructure and Mechanical Properties of Weld Metal of 960 MPa-grade Low-carbon Bainitic Steel
DOU Guishan1,2, CAO Rui1,2,*, JIAO Shishun1,2, YANG Fei3, ZHU Yuting3, ZHANG Kejing3, LIU Chuntao3
1 Department of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China 2 State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China 3 Sichuan Atlantic Welding Materials Co., Ltd., Zigong 643000, Sichuan, China
Abstract: To satisfy the principle of equal strength matching between welded joints and 960 MPa grade low carbon bainitic steel as closely as possible, this work studied the effect of different post-weld heat treatment temperatures on the microstructure and mechanical properties of weld metal of 960 MPa-grade low-carbon bainitic steel. Tensile tests and low-temperature Charpy impact tests were conducted on the weld metal with as-welded state and various post-weld heat treatment temperatures to determine the optimal balance between strength and toughness of the weld metal. The results indicate that the weld metal microstructure with as-welded state consists of granular bainite and primary eutectic ferrite. With the increase of the post-weld heat treatment temperature, the M-A constituent gradually decomposes, carbide precipitation occurs, and the Sorbite appears at 650 ℃. Post-weld heat treatment at a temperature of 550 ℃ results in the highest yield strength and tensile strength, but the lowest impact toughness. At-40 ℃, the impact energies of specimens heat-treated at 450 and 650 ℃ were both 65 J. The yield strength and tensile strength of the former were 925 and 992 MPa, respectively, and those of the latter were 771 and 887 MPa, respectively.
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2026, Vol. 40 
