Microstructure and mechanical properties of laser forming repaired 17-4PH stainless steel

The microstructure and microhardness of laser solid formed (LSFed) and laser forming repaired (LFRed) 17-4PH stainless steel were investigated. The mechanical properties of LSFed 17-4PH stainless steel and laser forming repaired (LFRed) 17-4PH stainless steel with the volume fraction of laser deposited zone (LDZ) of 5%, 30% and 60%, respectively, were also examined. The interface between the substrate and LDZ presented a compact metallurgical bonding. There existed the uniform distribution for the major elements of 17-4PH stainless steel, such as Fe, Cr, Ni, Cu, from the substrate to the LDZ. The microstructure of the LDZ consisted of martensite laths and a small amount of precipitation strengthening phase particles, such as M7C3 and NbC carbides. The microstructure of heat affected zone (HAZ) and the substrate mainly consisted of the ferrite strips and martensite laths. The hardness and tensile strength of the LDZ are higher than those of the wrought substrate, and its reduction of area is slightly lower than that of the wrought. The comprehensive mechanical properties of LSFed and LFRed 17-4PH stainless steel were equivalent with those of the wrought.