Laser cladding of Stellite 6 on stainless steel to enhance solid particle erosion and cavitation resistance

Abstract

Laser cladding of Stellite 6 on stainless steel 13Cr–4Ni has been performed to study the performance of clad on solid particle erosion (SPE) and cavitation erosion at varied energy densities (from 32 to 52J/mm2). Results are also compared with the AISI 304 stainless steel. The cladding geometry, dilution, microstructure and variation in microhardness were also investigated with laser energy inputs. The performance of cladded surfaces was studied for solid particle erosion and cavitation erosion resistance in 3.5% NaCl solution according to ASTM standard G76-07 and ASTM G32-07 methods respectively. Results indicated that clad dilution was 3–6% (geometrically) and 4.48% (compositionally) at 32J/mm2 that increased further with laser energy density. This accompanied compositional changes in the clad such that the Fe and Ni contents increased and Co, Cr, and W were observed to reduce with variation of laser energy density from 32 to 52J/mm2. The highest hardness (705Hv) of the clad was obtained at 32J/mm2 which reduced further by enhancing the laser energy density. Stellite 6 cladding has significantly enhanced the solid particle erosion resistance of stainless steel. Cladding at 32J/mm2 showed SPE and cavitation resistance than the cladding performed at higher laser energy densities. Cavitation erosion resistance of the stainless steel in 3.5% sodium chloride solution was enhanced by >90% by laser cladding. Lower corrosion current density of 13Cr–4Ni is observed after laser cladding which further increased with laser energy density. The erosion resistance obtained can be explained on the basis of dimensionless parameter related to kinetic energy. Cavitation resistance appears related to elastic recovery after cladding.