Microstructural characteristics of laser-clad AISI P20 tool steel

Laser cladding of P20 powder on AISI P20 tool steel substrate has been investigated for potential mold or die repair applications. The process was conducted using a 3 kW CO2 laser in continuous wave (CW) mode to melt the moving substrate while P20 powder was simultaneously fed into the molten pool. The process can accurately deposit material at desired locations with a relatively low heat input. A dense and crack-free clad layer was obtained with an excellent metallurgical bonding with the substrate. This study demonstrates that P20 powder can be deposited on P20 tool steel substrate without any pre-heating. The P20 clad layer has a higher hardness as compared to the P20 substrate. The microstructural morphology of as -clad P20 shows predominant martensite phase along with refined dendrites due to process-induced fast cooling. Moreover, the residual stress measurements indicate the presence of compressive residual stresses on the surface of the P20 clad.