Effect of Cu and Nb on Microstructure and Mechanical Property of Multi-layer Weld Metal

The effect of Cu and Nb on the microstructure and strength of weld deposits and physically simulated multi-pass weld metals was investigated by utilizing actual deposit containing different levels of Cu and Nb,Gleeble welding simulation,TEM and OM observations,as well as hardness measurement.The results show that the simultaneous addition of 3.0% Cu and 0.03% Nb in weld metal with high strength can offer required moderate precipitation effect with high thermal stability and uniformly distributed bainite as the matrix of reheated weld metals which result in a homogenous distribution of mechanical properties in either single-pass or multi-pass weld deposit.Moreover,the rigidity as high as 289 HV above is concreted in the weld metal by the combination effect of Cu and Nb elements added in the normal C-Mn weld metal.