Q345R封头热成形后强度偏低探讨

Discussion on Low Strength for Q345R Head after Hot Forming

结合对1188批次Q345R热成形封头母材试板数据统计分析,进行了模拟热成形(正火冲压)试验,以探讨封头热成形后母材试板强度低于GB/T 713-2014要求值的原因。分析结果表明;不合格现象主要出现在36 mm及以下钢板,且为热轧或控轧板。主要原因系封头在热成形过程中,钢板因轧制产生的形变强化作用消失,强度指标特别是屈服强度明显下降所致。采用热成形工艺制造36mm及以下封头时,应慎用热轧、控轧Q345R钢板。

Combined with statistical analysis on the data of 1188 batch test base plates of hot-formed Q345R head,the simulated hot-forming(normalizing stamping)test is carried out to explore the reasons for the lower strength of the test base plate after the head hot-formed than the required value specified in standard of GB/T 713-2014.The results showed that the lower properties mainly appeared in the 36 mm and below steel plates in hot-rolled or controlled rolled condition.The main reason is deformation strengthening effect in the hot-rolled or controlled rolled process disappears during the head is hot-formed,which results in decrease of strength,especially a significant decrease of yield strength.While hot-forming process is used for manufacturing the 36mm and below head,it should be cautious to use rolled or controlled rolled Q345R plates.