含铜时效钢模拟焊接热影响区的组织与性能

Microstructures and properties in simulated heat-affected zone of copper-bearing age-hardening steel

对含铜时效钢焊接热影响区粗晶区进行了焊接CCT图的测定及一次和二次模拟焊接热循环试验。结果表明,依据焊接CCT图可以大致确定实际冷却时间t8/5最佳范围为7~35 s。一次热循环试验表明,热连轧的含铜钢焊接热输入范围较窄,在较大热输入条件下,焊接热影响区粗晶区出现脆化,脆化的原因是t8/5较大时生成了大量的粒状贝氏体。t8/5大于7 s后,粗晶区开始出现软化。软化的原因是ε-Cu粒子的回溶、贝氏体板条宽化和铁素体数量增加共同作用的结果。二次热循环峰值温度Tp处于两相区时,发生显著脆化,脆化的原因是焊接冷却过程中形成了尺寸较粗大的粒状贝氏体及在原奥氏体晶界处形成了珠光体组织。

The experiments were carried out upon the determination of SH-CCT diagrams and the characteristics of microstructures and properties in simulated coarse grain heat-affected zone(CGHAZ) of hot continuously rolled copper-bearing steel under single and double welding thermal cycles using thermal simulation.The results show that with the help of SH-CCT diagram of copper-bearing steel,it is proposed to choose t8/5 ranging from 7 s to 35 s during welding.The copper-bearing steel has a narrow range of heat-input a...