Effect of Heat-Input on Microstructure and Toughness of CGHAZ in a High-Nb-Content Microalloyed HSLA Steel

Authors：Yu, Hongwei; Wu, Kaiming^*; Dong, Baoqi; Liu, Jingxi; Liu, Zicheng; Xiao, Daheng; Jin, Xing; Liu, Hankun; Tai, Minmin

Source：Materials, 2022, 15(10): 3588.

DOI：10.3390/ma15103588

• CGHAZ
• thermal cycle
• impact toughness
• niobium microalloying

The effect of various heat inputs on the microstructure and impact toughness of the simulated coarse-grained heat-affected zone (CGHAS) of a niobium microalloyed (0.14 wt.%) low-carbon steel was studied. The results showed that higher impact toughness was achieved at a low heat input of 20 kJ/cm, which resulted from the formation of acicular ferrite laths/plates. They sectioned large prior austenite grains into many smaller regions, resulting in smaller crystallographic grains and high-angle grain boundaries. Conversely, when specimens were simulated with larger heat-inputs (100, 200 kJ/cm), the microstructure of the CGHAZ was predominantly composed of granular bainite plus massive MA constituents, thus impairing the impact toughness.

• Institution
  华中科技大学