Q235D热轧钢板低温冲击性能不合原因分析及改进措施

针对重钢4 100 mm产线生产的厚度为16～25 mm Q235D热轧钢板低温冲击性能不合问题，通过对钢板化学成分、金相组织和轧制工艺进行分析，发现产生沿晶界呈连续带状分布的珠光体组织，并且同时伴随有混晶现象是导致钢板低温冲击性能不合的主要原因。将精轧终轧温度提高至890～900 ℃，改善了钢板组织形态，获得均匀的组织，提高了Q235D钢板低温冲击性能，满足了标准要求。

Cause analysis of unqualified low-temperature impact performance of Q235D hot rolled plate and its countermeasures

To the unqualified problem of low-temperature impact performance of Q235D plate with thickness of 16~25 mm produced in 4 100 mm production line in Chongqing Iron and Steel Co.,Ltd.,the chemical composition,metallographic microstructure of plate and rolling process were analyzed.It is found that the pearlite distributed in continuous bands along grain boundary and accompanied by mixed metallurgical structure phenomenon leads to unqualified low-temperature impact performance of plate.Therefore,the finishing rolling temperature was raised to 890 ～ 900 ℃,which improved the microstructure of the plate and obtained a uniform structure,the low-temperature impact performance of the Q235D steel plate was improved and met the requirements of standards. Key words：