The influence of microstructure on the low-temperature impact toughness of the heat-affected zones (HAZs) in C–Mn shipbuilding steels was investigated in welding thermal simulations and the Charpy impact test. Within the temperature range −80°C to −40°C, the Charpy impact energy initially increased and thereafter decreased with decreasing peak temperature of welding. The impact energy was maximised at a peak welding temperature of 850°C. The deterioration of low-temperature impact toughness was associated with enlarging effective grain size and numerous low-angle boundaries. The distribution of dual-phase structures and martensite/austenite (M/A) constituents significantly affected the fracture mode. The impact energy fluctuations observed in the analysis are also explained.

通过焊接热模拟和夏比冲击试验研究了显微组织对C-Mn船用钢热影响区（HAZs）低温冲击韧性的影响。在-80°C至-40°C的温度范围内，夏比冲击能最初会增加，然后会随着焊接峰值温度的降低而降低。峰值焊接温度为850°C时，冲击能量最大。低温冲击韧性的降低与有效晶粒尺寸的增大和许多低角度边界有关。双相结构和马氏体/奥氏体（M / A）成分的分布显着影响断裂模式。还说明了在分析中观察到的冲击能量波动。