焊后热处理对15CrMoR(H)钢焊条电弧焊焊接头组织与性能的影响

以15CrMoR(H)耐热钢为研究对象,采用 R307G焊条多道多层焊,分析了焊后热处理前后焊接热影响各分区的组织转变,并对焊接接头进行冲击试验及硬度检测。结果表明,焊后热处理前热影响区粗晶区为上贝氏体+马氏体组织,临界粗晶区在原奥氏体晶界生成链状脆性组织,导致其局部微区硬度偏高,冲击吸收能量较低,裂纹扩展区呈准解理断裂;焊后热处理后粗晶区为回火索氏体组织,临界粗晶区为晶粒内部的回火索氏体及晶界附近的链状高温回火组织,焊接接头整体硬度分布均匀,热影响区冲击吸收能量较高,断口形貌呈韧窝状的韧性断裂。

Influence of Postweld Heat Treatment on Microstructure and Properties of 15CrMoR(H) Steel SMAW Joint

With 15CrMoR(H) heat-resistant steel as the research object and by employing multi-pass multi-layer welding with R307G welding electrode,the microstructure transformation in different areas of HAZ before and after PWHT was analyzed,and the impact energy and hardness of welded joints were tested.The results show that the CGHAZ microstructure before the post-weld heat treatment was the upper bainite+martensite microstructure,and the IC-CGHAZ formed the chain-like brittle structure at the original austenite grain boundary,resulting in high hardness in the local micro-zone of the heat affected zone.The absorbed impact energy in the heat-affected zone was relatively low and the crack propagation zone shows quasi-cleavage fracture;the hardened microstructure of CGHAZ was transformed into the tempered sorbite microstructure,and the IC-CGHAZ microstructure was transformed into tempered sorbite inside the grain and a chain-like high-temperature tempered microstructure near the grain boundary after PWHT.The overall hardness of the welded joint was homogeneously distributed,and the impact absorption energy of the heat-affected zone was relatively high,and the fracture shows dimple ductile fracture.