Study On Eliminating Welding Residual Stress And Deformation By Real Time Ultrasonic Impact Treatment

Welding is an important manufacturing technology, and it plays a very important role in industrial production and the national economy. However, the existence of welding residual stress and deformation have many adverse effects on welded structures. This project is that, Ultrasonic Impact Treatment will be carried out to the back of weld bead near the molten pool so that two-direction tensile plastic deformation at the face side of weld bead is bulged and produced. It superposes the tensile plastic deformation produced in the cooling contraction stage of weld bead and counteracts the compressive plastic deformation produced during temperature rising stage. Finally, welding residual stress and deformation are eliminated.In this study, the finite element software ANSYS is used for simulating temperature field, strain field and stress field in the weldments. The distribution of temperature field and residual stress field and the status of residual deformation in the welding process can be got. This provides a theoretical basis for determining impact position and further determining the relationship between stress and strain. Then the infrared thermometer AR892+is used for measuring temperature of the points which have different distances from the center of the heat source and are located in the face and back side of3mm thin plate and10mm thick plate. Combining with ANSYS simulation results, the location of real-time ultrasonic impact treatment is determined ultimately.The study on eliminating welding residual deformation shows that using real time ultrasonic impact treatment can significantly reduce lateral residual deformation. But it has no significant effect on the longitudinal shrinkage. The effect on eliminating welding residual deformation is good when ultrasonic impact treatment is added in the high-temperature plastic zone. The shape and diameter of impact head also have great effects on eliminating deformation. When the impact head is spherical cap, its diameter is small (10mm) and real time impact is added in the high-temperature plastic zone, the average of lateral residual deformation of300mm long sample can reduce to0.03mm. The study on eliminating welding residual stress shows that using real time ultrasonic impact treatment has obvious effects on eliminating longitudinal residual stress, but it is not useful for horizontal residual stress regardless of built-up welding or butt welding. The effect on eliminating welding residual stress is good when ultrasonic impact treatment is added in the restore elasticity zone. Impact head shape has obvious effects on the amount of decreasing residual stress, while its diameter has small effects relatively. When the impact head is spherical cap and impact zone is restore elasticity zone, the average of the residual stress of built-up welding decreases about33.38%, and residual stress of butt welding decreases about55%.With the developing of ultrasonic impact treatment in the field of welding and the further theory research, using real-time ultrasonic impact treatment to eliminate welding residual stress and deformation will surely have a more broad application prospect.