Study On Performance And Adjustment Of Small Diameter T91 Weld Joint

As increasing boiler parameters,SA213-T91 small diameter tube is widely used in boiler reheater,superheater,and other important components.During the process of manufacturing for many years,boiler companies have accumulated many successful experiences of the processing of T91 welding technology.But in recent years,the quality problem is still frequent.The problems of small diameter T91 weld joint hardness anomaly and residual stress that easily lead to crack are the most important.In view of this situation,this paper mainly studies the hardness,residual stress and its adjustment of small diameter T91 joint.The post heat treatment process and sample status will affect the result of the hardness.In view of these factors,this paper did some test to verify the influence of different factors.The residual stress state and its thermal relaxation phenomenon is the basic of residual stress relaxation process of metal components.It is usually occur that the post heat treatment temperature is not enough for the T91 weld joint,so this paper did research on residual stresses relaxation in this kind condition.Shot peening treatment can improve the stress state of the material surface which also make the steel surface grain fragmentation at the same time,increase the dislocation density and lattice distortion can improve its oxidation resistance.This paper took three different kinds of shot peening process to T91 weld joint,and tested the residual stresses and hardness.