Effects of heat treatment on microstructure and micro-hardness of laser metal forming DZ125L superalloy

The microstructure of laser metal forming DZ125L superalloy was studied first. The non-equilibrium microstructure is dense, the primary spacing of dendrites is about 5 μm; the generated supersaturated solid solution inhibits γ' phase precipitation and punctuated MC carbides precipitates at the grain boundaries. Unless the necessary heat treatment, it couldn't be used directly. Studies of microstructure and micro-hardness on five kinds condition of heat treatment were carried out. The results show that the homogenization and solution treatment is necessary, but the time must be strictly control; the aging time can be reduced properly. The micro-hardness of the sample which fabricated with heat treatment is the lower than that with as deposit, as the microstructure is dense and strengthening phase MC carbide precipitates at grain boundary.