Research On Interface Microstructure And Mechanical Behavior Of Weld Joint Of Stainless Steel Clad Plate

The stainless steel cladplate is widely used in corrosion and high temperature environmentdue to its excellent performance and low cost.The composition and properties of stainless steel clad plate are different between carbon steel and stainless steel,which makes the stainless steel clad plate easy toemerge questions during welding process,such as the dilution and diffusion between carbon steel and stainless steel,the generation of brittle phase and so on.These problems will further affect the microstructure and performance of weld metal ofstainless steel clad plate.In order to control the content of alloy elements and avoid the hardening phase,and reduce the width of the fusize zone in weld metal,different groove form,welding methods and welding consumable were adopted to prepare excellent welding products.The designed four kinds of welding process are process A(V groove,no transition layer),process B(staircase V groove,no transition layer),process C(staircase V groove.transition layer through TIG welding)and process D(staircase V groove,transition layer through SMAW welding)respectively.The optimum welding process is determined through microstructure,element distribution,mechanical properties and fracture morphology of the different weld metal.The research results show that:1.All welds prepared with different processes have perfect appearance.There are no cracks,pores and slag inclusions in the weld,and all joints are well combined.The microstructure of stainless steel weld metalof A,C and D processes are both ferrite and austenite.In process A,the martensite structure appears in the carbon steel bottom weld metal.The martensite form in stainless steel weld metal near the carbon steel weld metalin process B.2.The results of elements distribution of weld metal show that the content of Cr,Ni in carbon steel backing weld metal is much higher than that of carbon steel base metalin process A.The content of Cr element in the stainless steel weld with B process is lower than that of the base stainless steel.The content of Cr in stainless steel weld metal is lower than that of the stainless steel base metalin process C,transition layer has poor isolation effect.The content of Cr,Ni in stainless steel weld metal is higher than that of the stainless steel base metal in process D,and the effect of transition layer is obvious.3.The mechanical performance test results show that the weld hardness value of process B is the largest and the value is 524HV,the process D is the smallest and the value is 295HV.The fracture positions of the tensile testsare locate at base metal far away from the weld metal,indicating that the weld metals satisfy the requirement of strength.There are no cracks in the bending specimens for the welds with four processes,and weld metal have high toughness.In notch bending tests,when the notch locate in the carbon steel weld metal,specimen possess highest bending strength.The bending performance of the weld with D process is the best among the processes of B,C and D.In process D,the impact energy values of the three directions at-40~oC are 49J?45J and 55J respectively,which has the best impact toughness.4.The fracture morphology analysis results show that all the bending fracture characteristics are ductile,the striped dimples in the edges are affected by the plane stress state.The fracture surface of stainless steel weld metal and transition layer is different from that of carbon steel weld,because they are diluted by carbon steel weld metal in different degrees.The dimples in stainless steel weld metal are deeper and larger than that of transition layer.