Advantage post weld heat treatment
Post Weld Heat Treatment Services (PWHT ) is defined as one of heat treatments done after welding machining to improve the mechanical properties of weldment I machined surfaces. In concept, PWHT covers many different potential treatments. However, in steel fabrication most common procedure used is Stress Relieving.
Stress induced by welding:
As a result of welding process used to join metals together. The base material near the weld metal and the heat-affected zones transform through various metallurgical phases. Depending upon the chemistry of the metals in their areas. Hardening occurs in various degrees. Depending mainly upon the carbon content. This is particularly very true in the heat – affected
zone adjacent to the weld metal deposit. The resultant stresses are highest due to melting and solidification. Stress, due to welding is of magnitude roughly equal to the yield strength of the base material.