Q690焊接接头组织及其残余应力分布研究

Study on Microstructure and Residual Stress Distribution of Q690 Welded Joints

对Q690试板分别采用同质和H08Mn2SiA焊丝进行了TIG焊接。利用OM对焊缝组织进行观察,用盲孔法对焊接接头残余应力进行测试,用万能试验机和硬度试验机测试了焊接接头的力学性能,并用SEM观察分析了拉伸断口形貌。结果表明,焊缝纵向残余应力受相变的影响较大。用同质焊材填充时焊缝组织为粒状贝氏体,焊缝残余应力为350 MPa,热影响区为370 MPa;用H08Mn2SiA填充时,焊缝组织为铁素体,焊缝残余应力为270 MPa,热影响区为330 MPa。两种接头均为近强匹配,拉伸断裂为韧性断裂,可满足焊接接头力学性能。焊缝硬度值均较低,热影响区最大硬度值达到340 HV。

Q690 test panels were welded with homogeneity and H08Mn2SiA wires using TIG welding. The microstructure of the welded joint was characterized by optical microscopy （OM）. The residual stress of the weld joints was tested by using blind hole method. The mechanical properties of the welded joint were tested by universal testing machine and hardness tester （HV）, and the morphology of the tensile fracture was observed by SEM. The results show that longitudinal weld residual stresses are greatly influenced by phase transformation. Filled with homogeneous filling,the microstructure is granular bainite, the residual stress of weld and heat-affected zone are 350 MPa and 370 MPa is 270 MPa and 330 MPa, respectively. Two kinds of the welded joints are strong in recent match and the tensile fractures are both ductile fracture. The hardness of both welds are lower, and the maximum hardness of the heat-affected zone reaches 340 HV.