Effects Of Combined Technology Of Electroulsing And Ultrasonic Impacttreatment On Propeties Of Welding Components

Welding components had been widely used in the industry. Since welding is a rapid heating and cooling unequilibrium process, welding residual stress usually appeared in the welded components at the same time. It can affect the functioned performance of the components seriously, and results in the ease of fracture, reduction of both corrosion resistance and fatigue life of welded components during their service. Thus, developing a facile post-welding treatment technology to improve the performance of welded component has become an urgent issue nowadays.In this paper, a combined technology of high energy electropulsing and ultrasonic impact treatment was used in S50 C steel welding components. The influences of such combined technology on eliminating welding residual stress, refining microstructure and improving the surface mic rohardness in the joint were studied by comparing with the traditional ultrasonic impact treatment. The impact of electropulsing current density applied on welding components to the treatment efficiency was also analyzed in the paper. Blind hole method was introduced to measure the residual stress of welding areas. Three-dimensional optical microscopy and scanning electron microscopy were used to observe the microstructure of the welding joints. The microhardness of the welding joints was obtained by using a microhardness tester.The analytical results showed that using the combined technology of electropulsing and ultrasonic impact treatment with the optimized current density gives a better capability of eliminate welding residual stress within the welding component compared to the traditional ultrasonic impact treatment. The elimination rate of the first main stress and the second main stress can reach 380% and 500% respectively after 3 min treatment. However, when the current density further increased, the elimination rate of residual stress reduced.For the microstructure refining aspect, with the optimized current density, the combined technology of electropulsing and ultrasonic impact treatment can improve the surface plastic deformation level, refine th e microstructure and increase the depth of refining layer in welded components. If the current density is too small, no obvious refining microstructure of welding component can be achieved. However, the excessivecurrent density can reduce the extent of sur face plastic deformation.For the surface microhardness aspect, with the optimized current density, the combined technology of electropulsing and ultrasonic impact treatment can improve the maximum surface microhardness, and increase the depth of hardness reinforcement layer of welding joints. Like the influence to the microstructure, when the current density is under a certain level, the electropulsing assisted ultrasonic impact treatment did not show any significant strengthening effect on surface microhardness of the welding component. With the excessive current density, such treatment can reduce the maximum surface microhardness, whilst the depth of depth of hardness reinforcement layer remains at the same level.