新型工程机械用Q550钢气保焊性能研究

Study on the GMAW weldability of new type Q550 steel for engineering machinery

采用Φ1.2mm的WH70-G的实芯气保焊丝对16mm厚的新型Q550D钢板进行富氩气体保护对接焊,针对焊接接头分析了显微组织,进行了拉伸、弯曲、冲击、硬度等力学性能检测。接头断面上没有发现气孔、夹杂、裂纹等明显缺陷,焊缝区组织为针状铁素体+先共析铁素体,热影响区粗晶区组织为粒状贝氏体;接头抗拉强度达到760 MPa,断裂位置均位于母材,D=3a,180°冷弯试验合格,接头塑性良好,焊缝、熔合线、热影响区-20℃冲击功均大于47J。表明所采用不预热的焊接工艺能够满足Q550D钢的焊接技术要求。

Through gas metal arc welding method,theΦ1.2 mm solid welding wire WH70-G was used for the butt welding of new type Q550 steel,the microstructure of welding joint were observed,and the tensile,bending,impact and hardness mechanical properties were tested.The results show that,no pores,inclusions,cracks and other obvious defects was found in macro morphology of the joint cross section,the microstructure of the weld metal was acicular ferrite and proeutectoid ferrite,the CGHAZ microstructure was granular bainite;joint tensile strength reached 760 MPa,and the fracture positions were in the parent material,d=3a,180°cold bending test qualified,which shown the joint plasticity was good,and the impact toughness of weld metal,fusion line and HAZ at-20 ℃were all greater than 47 J.It indicated that the no pre-heat welding process can satisfy the welding technical requirements of Q550 Dsteel.