Q460C中厚钢板正火前后性能不合格原因分析

Analysis on Disqualification Causes of Mechanical Properties for Q460C Medium Steel Plate before and after Normalizing

在Q460C低合金高强度中厚钢板开发过程中,通过采取微合金化和TMCP相结合的工艺措施,对轧制态伸长率不合格钢板进行正火处理,并对比分析轧制态和正火态钢板的组织、性能。结果表明:轧制态钢板产生严重珠光体带状组织、中心局部区域M+B组织以及混晶组织,是钢板伸长率不合格的主要原因;而正火后钢板组织晶粒比正火前粗大,是屈服强度和抗拉强度降低的主要原因。正火处理起到促使钢板组织均匀化、改善伸长率的作用,据此提出工艺优化建议。

In the process of developing Q460 C low alloy higher strength medium steel plate,normalizing is performed on as-rolled steel plate with disqualified elongation ratio by adopting microalloying and TMCP,comparative analysis is carried out on microstructure and mechanical properties of as-rolled and normalized steel plate.The results show that severe pearlite banded structure,martensite+bainite in center local zone and mixed grain microstructure form in as-rolled steel plate,which is the major cause of the elongation ratio disqualification,while the grains after normalizing are much coarser than those before normalizing.The normalizing treatment improves microstructure homogenization and elongation ratio.The optimization suggestion on process is proposed hereby.