Study On The Microstructure And Properties Of CMT And Micro-plasma Arc Welding Joints Of 06Cr19Ni10 Austenitic Stainless Steel

In recent years,austenitic stainless steel sheet has been widely used in the manufacture of railway locomotives,making the welding of austenitic stainless steel sheet has become one of the important development direction of railway locomotive industry in our country.Because the small thermal conductivity,high resistivity,large coefficient of linear expansion and other characteristics of austenitic stainless steel than ordinary carbon steel.so in the welding process is prone to burn and large welding deformation,but also will produce large thermal stress.Cold metal transfer welding as a new welding technology,has no spatter,lower heat input,effectively improve the characteristics of spatter,bad shape and large heat input of the traditional welding methods;micro-plasma arc welding is a kind of high energy density,heat concentration,stable welding arc,narrow HAZ,little welding deformation and excellent performance of welding joints.At present,both kinds of high quality welding methods have been a highly efficient and reliable welding method for the welding of thin plate of stainless steel locomotive body.In this paper,research on microstructures and properties of 1.5mm thick 06Cr19Ni10austenitic stainless steel welded joints of cold metal transfer welding and micro-beam plasma arc welding,through the conventional mechanical tests such as tensile,bending,hardness and microstructure analysis.The fatigue performances of 06Cr19Ni10 austenitic stainless steel welded joints of both kinds of welding methods were studied by the pulsating tensile fatigue tests.And the results of the median fatigue strength were compared and analyzed within cold metal transfer welding welded joint and micro plasma arc welded joint.The results show that:The microstructure of welded joints are austenitic+different formsδferrite,and the microstructure of cold metal transfer welding zone is more fine and uniform than micro plasma arc welding;Tensile performance and bending performance of06Cr19Ni10 stainless steel cold metal transfer welding welded joints and micro plasma arc welding butt joints are good,meet the requirements standard,and compared with cold metal transfer welding joints,the micro plasma arc welding tensile strength is lower 36.5MPa;the hardness of weld zone and HAZ（220²27）are lower than base metal,and the hardness is gradual increased from HZA to base metal;hardness of welding zone of cold metal transfer is higher than micro plasma arc welding 10HV;Welded joints of 06Cr19Ni10 stainless steel welding median fatigue limitσ_0.1:the fatigue strength of cold metal transfer welding butt joints is higher than micro beam plasma arc welding butt joints 10 MPa,the fatigue strength of cold metal transfer welding lap joints is higher than micro beam plasma arc welding lap joints 4 MPa.