Effect of Post-weld Heat Treatment on Mechanical Properties at High Temperature of ENiCrFe-7 Weld Overlay Cladding Materials

The effect of the post-weld heat treatment (as-weld, 615 degrees C/16 h, and 615 degrees C/48 h) on the mechanical properties at the high-temperature of ENiCrFe-7 weld overlay cladding materials has been investigated by the microstructure observation combined with the tensile test. The results show that the precipitates increase not only in the grain boundaries (Nb5Si3 and Cr23C6), but also in the interdendrites (NbC) with increasing the heat treatment time, and the residual stresses first decrease which result from their being relieved by the heat treatment, and those of precipitates increase which result in the residual stresses slightly increased. For the heat treatment alloy ENiCrFe-7 after 615 degrees C/16 h, it has the worst tensile strength. However, for that of alloy ENiCrFe-7 after 615 degrees C/48 h, owing to having the most intergranular and interdendritic precipitates, it has the best tensile strength. On the other hand, the elongation gradually increases with increasing the heat treatment time which results from the precipitations of the NbC particles.