Effect of energy density on quality and properties of 18Ni300 laser clad layers by laser cladding

By preparing the 18Ni300 laser clad layers at different energy densities, the pores of the laser clad layers were measured and analyzed by using the image method, and the effect of energy density on the porosity was explored by combining the experimental data. The experimental results show that the cross-sectional pores of the laser clad layers are regular in shape and do not intersect with each other, and most of the pores are gathered at the top edge of the fused cladding layer. The influence of process parameters on the morphology of the laser clad layer is obvious. The study shows that the influence of process parameters on porosity is in the order of laser power, scanning speed, and powder feeding voltage; combined with the analysis of variance table and response surface diagram, the interaction between the parameters is obvious, and combined with the change, it can achieve the purpose of reducing porosity. Porosity first increases and then decreases with the increase in the energy density, and the distribution of the energy density and porosity is divided into regions, and larger porosity can be avoided by selecting the regions. The hardness of the laser clad layer can be increased by the choice of energy density. The laser clad layer with good test results was observed to contain Co, α-Fe, and Fe7Ni3 intermetallic compounds. The microstructure is transformed from fine grains at the top to columnar dendrites at the bottom.