Abstract：The reasonable matching of strength and toughness has always been the research difficulty of hot rolled coil for 700L automobile beam steel with 16 mm ultimate thickness specification. The microstructure, inclusions and impact fracture morphology of 700L automobile beam steel with 16 mm ultimate thickness specification were detected by optical microscope, scanning electron microscope and energy spectrometer, and the main factors affecting the low-temperature impact toughness of test steel at -20 ℃ were analyzed. The results show that the main reason for low impact absorb energy of test steel at -20 ℃ is a large number of inclusions(Nb,Ti)(N,C) with the length of 2-8 μm in the steel, the ferrite grains are not uniform at 1/2 of plate thickness, and there are pearlite segregation bands. The low temperature impact toughness of hot rolled coil of 700L automobile beam steel with ultimate thickness is improved significantly by reducing the nitrogen content in steel, increasing the thickness of hot rolled intermediate billet, reducing the mass fraction of liquation (Nb,Ti)(N,C) and refining the ferrite grain size at 1/2 of plate thickness.
季德静, 杨维宇, 崔博. 16 mm极限厚度规格700L汽车大梁钢低温冲击韧性优化[J]. 中国冶金, 2022, 32(3): 49-54.
JI De-jing, YANG Wei-yu, CUI Bo. Optimization on low temperature impact toughness of 700L automobile beam steel with 16 mm ultimate thickness specification[J]. China Metallurgy, 2022, 32(3): 49-54.
YAN W, SHAN Y Y, YANG K.Effect of TiN inclusions on the impact toughness of low-carbon microalloyed steels[J]. Metallurgical and Materials Transactions A,2006,37(7):2147.
2022, Vol. 32 
