Effect of energy input on porosity and microhardness in laser cladding coating on fgs600-3a ductile cast iron

Abstract

Laser cladding, which is surface modification technology, is based on melting with a laser beam by spraying powder on the base metal and generated by depositing the layers. In this study, the Metco 42C martensitic stainless steel powder material was cladded on the FGS600-3A ductile cast iron used in sheet metal forming molds. The effect of energy input on porosity and microhardness was investigated. The digital image processing method was used for porosity analysis. The energy input had a significant effect on the pore formation. The lower energy input (1.1 kW laser power, 14 mm/s scanning speed) resulted in lower porosity. The cladding thickness varied depending on the scanning speed parameter due to affecting powder efficiency, high thickness was obtained at 6 mm/s low scanning speed. In the upper layer of the cladding, high hardness values were achieved due to the martensitic phase formation. The bottom layers of cladding had lower hardness values because of the tempering of the hard martensitic phases by subsequent cladding processes. Significant increase in hardness at cladding zone was attributed to carbon transfer from the base metal. This remarkable increase in hardness was much higher at lowest energy input (1.1 kW laser power and 14 mm/s scanning speed). However, it is clear that this will increase the risk of crack formation because of brittleness. On the other hand, at the higher energy input, this significant increase in hardness is at a lower level due to rest-austenite formation and excessive annealing with subsequent cladding processes.