Optimization of laser cladding process parameters of a martensitic stainless steel coating on ggg70l ductile cast iron

Abstract

Laser cladding is an additive manufacturing (AM) method that is widely implemented in surface modification and repair. In this study GGG70L ductile cast iron base material (BM) was clad with Metco 42C martensitic stainless steel powder using a high power diode laser (HPDL) laser. The effect of process parameters (laser power, scanning speed and powder flow rate) on clad geometry, porosity and crack formation, and microhardness was investigated. Taguchi experimental design was created via the L9 orthogonal array and analysed by signalto-noise (S/N) ratio and analysis of variance (ANOVA) method for clad geometry. Clad geometry was investigated in terms of clad height, clad width, aspect ratio and clad depth using an optical microscope. Pores in the clad were characterized with an optical microscope and a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectroscope (EDS). Hardness testing of the clad layers was performed on a Vickers microhardness testing machine to create microhardness depth profiles. High laser power increased the risk of crack and pore formation, and led to larger pores. The optimum laser process parameters for the lowest pore and crack formations were a laser power of 1.7 kW, a scanning speed of 10 mm/s and a powder flow rate of 12 g/min.