Abstract：The 20Mn2 steel bar was sampled for chemical composition analysis, fracture detection, hardness test and metallographic structure observation. Combined with the forging and heating process of steel bar, the reason for the unqualified toughness in low temperature impact test was analyzed. The results showed that the widmanstatten structure and overheated structure appeared in the metallographic structure of steel bar due to too high forging heating temperature or too long time, which were not fully eliminated during the subsequent normalizing heat treatment. It was the main reason for unqualified low temperature impact of steel bar.
李翼飞，朱斌，王春奕，张全新. 20Mn2钢棒低温冲击不合格原因分析[J]. 物理测试, 2021, 39(3): 53-.
LI Yifei，ZHU Bin，WANG Chunyi，ZHANG Quanxin. Analysis on unqualified reason of 20Mn2 steel bar under low temperature impact. PHYSICS EXAMINATION AND TESTING, 2021, 39(3): 53-.
2021, Vol. 39 
