Study On Microstructure And Mechanical Properties Of 05CuPCrNi Steel Plasma Arc Welding Joint

By using the thin plate structure,the railway vehicle can effectively reduce weight,save materials,reduce energy consumption,but due to the small degree of restraint,welding is locally heated so that the sheet structure produces uneven stress and strain,will cause serious welding deformation.Plasma arc welding is a kind of high temperature new heat source and high energy density compression arc welding method.it has the characteristics of energy concentration,good arc adjustability,fast welding speed and large arc impact force.so the weld heat affected zone is narrow,high weld quality,especially small current welding Arc work is stable,the workpiece welding deformation is small,easy to get high-quality weld molding and metallographic structure.Plasma arc welding can be used to reduce the deformation of the sheet structure welding,.In order to determine the welding effect of plasma arc welding thin plate 05 CuPCrNi atmospheric corrosion resistant steel rail vehicle steel,the mechanical performance and microstructure of the 05 CuPCr Ni atmospheric corrosion resistant steel butt joint and lap joint were studied by plasma arc welding and MAG welding to verify the superiority of the application of the fusion type plasma arc welding technology in the production of rail vehicles.The main contents of this paper: the microstructure and mechanical properties of 05 CuPCrNi plasma arc welding and MAG welded with ER50-G wire were studied by welding process,tensile,bending,metallographic,hardness and fatigue test.The microstructure and mechanical properties of plasma arc welding and MAG welding joint were compared.The results show that the tensile strength of 2mm thick 05 CuPCrNi atmospheric corrosion resistant steel plasma arc welding and the MAG butt joint are good,and the tensile strength of plasma arc welding joint is slightly higher than that of MAG welding.The fracture edge and center of the specimen are all dimple and the fracture type is ductile fracture.Both the fusion type plasma arc welding and the MAG butt joint have good bending performance.2mm thick 05 CuPCrNi atmospheric corrosion resistant steel butt joint hardness value: MAG 185 HV ~ 220 HV,plasma arc welding for the 152 HV ~ 229 HV,two kinds of welding methods under the weld hardness are higher than the base metal.2mm thick 05 CuPCrNi atmospheric corrosion resistant steel base metal at room temperature are the ferrite and pearlite,MAG heat affected zone are the microstructure of first quenched ferrite,acicular ferrite,a small amount of carbon-free bainite and pearlite,the weld structure are first quenched ferrite,side panels of ferrite(carbon-free bainite)and layered pearlite.The microstructure of fusion-welded plasma welding heat affected zone is uniform,fine ferrite and pearlite.The microstructure of the weld is acicular ferrite,massive ferrite and pearlite.The welds of the fusion-welded plasma welds are smaller than those of the MAG welds in both the weld and heat-affected zones.The median fatigue limit of the two types of welds is increased by 225% and 58%,respectively,compared to that of the butt joint.Plasma arc welding is almost no more than high,too smooth at the weld toe and the uniform and small organization are the main reasons of the improving of 05 CuPCrNi resistant atmospheric corrosion resistant steel plasma welding butt joints(retention of high)and the lap joint fatigue performance.Plasma arc welding in welding 2mm thick 05 CuPCrNi resistant to atmospheric corrosion of steel,both the appearance and mechanical properties are better than MAG welding.