Local Postweld Heat Treatment of Heterogeneous Welded Joint

A concept of heterogeneous welded joint is proposed for researching and describing the characteristics of local postweld heat treatment (PWHT) temperature field for asymmetric thermal conductivity welded joint. Its three types have been classified according to thermal conductivity direction around the weld, separately, welded joint with transverse unidirectional thermal conductivity, transverse bidirectional thermal conductivity, transverse and longitudinal thermal conductivity. Compared with the temperature field of symmetric thermal conductivity welded joint, the highest temperature point of heterogeneous welded joint deviates from the heat device center, and uniform temperature area shrinks. In addition, longitudinal temperature difference and dramatic temperature change zone have arisen for the third type heterogeneous welded joint. In order to improve the temperature distribution, two PWHT methods called temperature compensation method and power compensation method have been put forward and developed. Several engineering applications of two methods are illustrated as examples.