Correction For Aluminum Alloy Sheet Welding Buckling Distortion By Ultrasonic Shot Peening

Buckling distortion is a prominent problem in the welding of Aluminum, which affects the manufacturing precision and performance seriously. In this paper, the method of correcting welding buckling distortion by ultrasonic shot peening was proposed. The research about distortion correction technology by shot peening is rare at home and abroad.The effects of shot peening parameters on the correction effect were studied in this paper. By comparing experimental results of different peening region, peening gun moving speed, peening power and peening coverage, such qualitative conclusions were drawn. The peening region should be determined based on the area of compression plastic strain which occurred in the welding process. Too large or small value will both reduce the correction effect. In this paper, the selection of 40mm as the width of peening area achieved the best effect. On the condition of 100% coverage in one peening process, the increase of staying time in one point for the peening gun which represented the decrease of its speed had little effect on reducing the distortion. In order to improve the efficiency of correcting the distortion, the staying time for the peening gun should be set as a short time which could be 1 s. With the increase of the peening power, the orthopedic effect got better. To avoid the generation of additional bending deformation, the shot peening should be conducted symmetrically. When the coverage of shot peening reached 100% and both sides of the specimen were peened once, more times of peening has little effect on the deformation.The microstructure organization, hardness and tensile properties of the welded specimens and specimens after shot peening were analyzed for comparison. The grain on the surface had significant deformation after shot peening. The hardness of the weld decreased compared to base metal. The hardness of in the range of 1.5mm distance from the surface increased for the specimen after shot peening. The strength of the weld joints was decreased by 7% relative to the base metal. The yield strength and tensile strength of the weld specimen was increased respectively by 3.4% and 26.5% and the elongation was decreased by 52.6%. This means the strength and hardness of the specimen was increased, but the toughness decreased after shot peening.The finite element software ABAQUS was used for simulating the process of welding, peening, and the correction of distortion by shot peening. The welding stress field, the distortion, and the plastic strain distribution were obtained. The plastic strain distribution provided a basis for the determination of shot peening area. The stress and strain field was obtained by shot peening process simulation. The stress simulation results were similar to the experiment results, which showed that the simulation of peening is valid. The change of the stress and strain before and after shot peening was obtained by the simulation of shot peening based on welding stress and distortion, which showed the mechanism of the decrease of distortion after shot peening.