Research on Microstructure and Properties in Welded Joint of 700 MPa Grade Low Carbon Micro-Alloy Steel

Abstract:

Microstructure and mechanical properties of automobile beam used BS700MC low carbon micro-alloy steel welding joint were investigated by cold crack sensitivity, microhardness test, bending, impact, tensile and metallographic analysis. The results showed that the BS700MC steel has better crack resistance, and without heat treatment before welding with the WH80-G welding wires. The microstructure of joint’s weld seam is acicular ferrite, very little bainite and proeutectoid ferrite. The hardness value of weld seam zone is 380 HV and is the same as that of base metal. But the lower of weld joints rigidity has obvious fluctuations, and the HAZ appears softened phenomenon. The welding joint has good impact toughness only between 20 and minus 20 degrees Celsius.The tensile strength of BS700MC welded joint reaches 815 MPa, 97.1% of base metal, fracture position in HAZ. Tensile fracture morphology is mixed type indicating dimple and cleavage steps, and welding joint have good comprehensive mechanical properties.

• Periodical: Advanced Materials Research (Volume 1088)
• Pages: 174-180
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1088.174
• Online since: February 2015
• Authors: Jian Feng Gu, Yi Xiao, Kai Jun Zhou, Dong Dong Dai, Qing Dong Zhong
• Keywords: 700MPa, Low Carbon Micro-Alloy Steel, Mechanical Property, Microstructure, Truck Frame, Welding Joint

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