The Effect Of Ultrasonic Impact Treatment On The Structure, Mechanical Properties And Stress Of Duplex Stainless Steel S32101 Joints

S32101 duplex stainless steel has excellent comprehensive performance and has widely used in nuclear power and transportation chemicals.The high heat input and rapid cooling in S32101 welding process lead to the generation of welding residual stress.The welding residual stress will have corrosion resistance to the welded structure.,the fracture resistance and fatigue performance caused by the damage,so it is very important to accurately evaluate and regulate the residual stress of the weld.Therefore,this paper takes 25mm thick S32101stainless steel butt joint as the research object.After welding,the surface is treated with ultrasonic shock,and the welding residual stress on the surface of the test piece before and after ultrasonic shock treatment is measured by XRD method.The surface residual stress of ultrasonic impact treatment is studied.Influence range;the residual stress inside the weld is tested by the contour method,and the influence depth of the surface ultrasonic impact is analyzed;the SYSWELD finite element simulation S32101 welding process,and the second development of SYSWELD is used to simulate the ultrasonic impact process,and the simulated residual stress results are the actual comparison is made.The influence of ultrasonic shock treatment on the microstructure,corrosion resistance and micro-shear mechanical properties of stainless steel welded joints is analyzed.XRD surface residual stress test shows that different ultrasonic impact parameters have different effects on the welding residual stress of S32101.The best effect is obtained when the ultrasonic impact strength is 10s/cm~2,and the tensile stress of 600MPa at the weld toe can be transformed into compressive stress of 600MPa.The residual stress of the S32101 weld was tested by the contour method.It was found that the residual stress gradually increased from the base metal to the weld.The entire weld area was tensile stress and the longitudinal peak stress was about 450~500MPa.The internal stress of the weld increases gradually along the thickness direction,and the peak tensile stress appears on the near surface of the weld center.The depth of the surface ultrasonic impact on the longitudinal stress is 0~2mm.The finite element simulation results of SYSWELD show that the overall trend of welding residual stress of S32101 is consistent with the measured value of actual residual stress.For the secondary development of heat source,the modified heat source is loaded into the workpiece as a force load to simulate the ultrasonic impact process.The simulation results and actual measured values.The trend is consistent and the simulation is available.The surface ultrasonic shock treatment has little effect on the deformation of the S32101test plate.After the ultrasonic impact,the base metal and the weld are plastically deformed.The ferrite in the base metal is compressed,the austenite is elongated,and the microstructure is refined.The microstructure of the weld surface produces severe plastic deformation,the austenite is refined,and the refined grains are laid flat on the impact surface.No new tissue was produced after the ultrasonic shock.The refinement of the microstructure and the increase in austenite resulted in an increase in the corrosion resistance of the S32101 duplex stainless steel and its welds after ultrasonic shock.After ultrasonic shock treatment,the hardness distribution of the surface layer is more uniform,the hardness of the impact layer is significantly improved,and the influence depth is 1~2mm.The punching shear strength of the base metal and weld impact area is improved after ultrasonic shock treatment.