论文部分内容阅读
为了研究SS400低合金高强钢焊接热影响区组织及硬度变化规律,利用膨胀仪模拟并测定了SS400钢热影响区组织临界相转变温度并绘制出SH-CCT曲线,并对其显微组织及硬度进行了分析。结果表明,当冷速在0.1~20℃/s时,主要发生铁素体+珠光体转变,随着冷速增加,珠光体含量增多,且铁素体晶粒减小,硬度增大;当冷速在30~80℃/s时,发生贝氏体转变;当冷速大于100℃/s时,形成大量马氏体。SS400钢碳当量为0.257%,冷裂敏感系数为0.203%,说明其淬硬倾向较小,焊接热影响区不易产生冷裂纹。
In order to study the microstructure and hardness variation of heat-affected zone of SS400 low-alloy high-strength steel, the microstructure and hardness of SS400 steel were simulated and measured by means of dilatometer, and the SH-CCT curve was drawn. Analyzed. The results show that when the cooling rate is between 0.1 and 20 ℃ / s, the ferrite + pearlite transformation occurs mainly. With the increase of cooling rate, the pearlite content increases and the ferrite grain size decreases and the hardness increases. When the cooling rate is 30 ~ 80 ℃ / s, bainite transformation occurs; when the cooling rate is greater than 100 ℃ / s, a large amount of martensite is formed. SS400 steel carbon equivalent of 0.257%, cold cracking susceptibility coefficient of 0.203%, indicating less tendency to harden, heat affected zone is not easy to produce cold cracks.