热处理前后09MnNiDR钢焊接临界粗晶区的力学性能分析及影响机制

Mechanical performance analysis and influence mechanism research of the welding critical coarse-grained zone of 09Mn Ni DR steel before and after heat treatment

采用热模拟试验机模拟低温压力容器用钢09MnNiDR的焊接过程,分析其焊接临界粗晶区的显微组织,对比分析焊接热处理前后09MnNiDR钢的力学性能,同时研究09MnNiDR钢冲击性能产生重要影响的机制.研究结果表明：09MnNiDR钢焊接临界粗晶区内的马氏体-奥氏体岛是其产生裂纹的源头,是造成09MnNiDR钢冲击性能变差的主要因素.通过不同的焊后热处理温度,发现在550℃～630℃温度区间内,09MnNiDR钢的低温冲击性能将明显改善.

This paper simulates the welding process of 09MnNiDR steel that is used for manufacturing the low temperature pressure vessel by adopting thermal simulation testing machine,and analyzes the microscopic structure of the welding critical coarse-grained zone.The compared analysis of the mechanical performance of 09MnNiDR steel before and after the heat treatment after welding is also analyzed,and the mechanism produced the important impact on the impact toughness of 09MnNiDR is studied at the same time.The research resuhs show that the martensitic-austenitic island in the 09MnNiDR critical coarse-grained zone is the origin of the cracks,meanwhile,it is the main factor that impacts the impact performance of 09MnNiDR steel grows worse.Through different heat treatment after welding,we can find in the range of 550 ℃～630 ℃ temperature,the low temperature impact performance of 09MnNiDR steel will be improved significantly.