4.5Cr耐候钢GMAW接头组织及力学性能研究

Microstructure and Mechanical Properties of GMAW Joint of 4.5Cr Weathering Steel

在不预热的条件下,采用TH650EW型焊丝对4.5Cr耐候钢进行熔化极气体保护焊(GMAW)试验。通过扫描电镜观察和力学性能试验,分析焊接接头的微观组织及力学性能。结果表明,焊缝区组织主要由粒状贝氏体与马氏体组成;粗晶热影响区组织主要为马氏体,细晶热影响区组织由细小的贝氏体和铁素体组成。4.5Cr耐候钢接头具有良好的力学性能。接头焊缝区和热影响区的硬度高于母材,没有出现软化区;其室温抗拉强度达到580MPa,断口出现在母材;同一冲击温度下,热影响区的冲击吸收功明显大于焊缝区,而且不同冲击温度下热影响区的冲击性能变化较小。

The gas metal arc welding (GMAW)test of 4.5Cr weathering steel was carried out by using TH650EW welding wire without preheating.The microstmcture and mechanical properties of the welded joint were investigated by SEM and mechanical properties tests.The results show that the microstructure of the weld zone mainly consists of granular bainite and martensite.The microstructure of coarse grain heat affected zone (CGHAZ)is mainly martensite.While the microstructure of fine grain heat affected zone (FGHAZ)is mainly composed of small bainite and ferrite.4.5Cr weathering steel joint has good mechanical properties.The hardness of the weld zone and the heat affected zone of the joint is higher than that of base material,and there is no softening zone.The tensile strength at room temperature reaches 580MPa,and the fracture appears on the base material.Under the same impact temperature,the impact absorption energy of the heat-affected zone is obviously bigger than that of the weld zone,and the impact performance of the heat-affected zone varies little under different impact temperatures.