Reduction of Residual Stress for Welding Joint Using Ultrasonic Vibrational Load.

Abstract

Welding is widely used for construction of many structures. The residual stresses created in a structure by a welding operation may influence the mechanical behavior of the structure in several ways. Hence, reduction of the residual stress caused by welding is very important. Stress relief may be accomplished by heating operation. However, processing by heat treatment requires much electric energy, processing time and so on. While, low frequency vibratory stress relief process has been reported as an effective method. However, this process has a limitation in applicability for high rigid parts such as dies and thick plates. In this paper, a new method for reduction of welding residual stress and its analytical model are proposed. The new method is carried out using ultrasonic vibrational loading which is applied during the welding operation. The proposed method is applicable to not only a structure consist of plate but also a massive block. An experiment was carried out for single-pass butt-welding of steel plates and single-pass repair welding of steel blocks. It is confirmed that the peak residual stress on the bead is significantly reduced. Furthermore, reduction of residual stress is examined by an analytical method using a mechanical model considering local plastic deformation.