Effects of Ultrasonic Impact Treatment on the Residual Stress and Microstructure of TA15 Welded Joint

Abstract

The effects of ultrasonic impact treatment (UIT) on the distribution of residual stress and on the microstructure of TA15 (Ti-6.5Al-2Zr-1Mo-1V) alloy joints by electron beam welding (EBW) were investigated. The results demonstrated that a marked microstructure change occurred after welding and the microstructure of welded joint presented a transitional change, i.e. martensite appeared in the fusion zone while equiaxed α in base mental. The residual stress in fusion zone was mainly tensile stress, and the maximum longitudinal stress value was 817MPa, which located in the centerline of welded joint. The results indicated that different impact methods have different influence on residual stress distribution. After employing UIT on welding toe, the residual stress near the welded joint exhibited a uniform distribution and the maximum tensile stress dropped to-153MPa. While after applying UIT on full coverage, the curve of the residual stress was steep and the maximum stress was still tensile stress. After UIT, no significant change occurred in microstructure and the tensile strength has a little change.