Hardfacing of mild steel with wear-resistant Ni-based powders containing WC particles using PPTAW technology

Abstract

This study explores the use of powder plasma transferred arc welding (PPTAW) as a surface layers deposition technology to form hardfaced coatings to improve upon the wear resistance of non-alloy structural steel. Hardfaced layers/coatings were prepared using the PPTAW process with two different wear-resistant powders: PG 6503 (NiSiB+60% WC) and PE 8214 (NiCrSiB+45% WC). By varying the PPTAW process parameters of plasma gas flow rate (PGFR) and plasma arc current, hardfaced layers were prepared. Microscopic examinations were carried out to ascertain information about the microstructure and surface characteristics of the prepared hardfaced layers. Penetration tests were performed to ascertain the number and depth of crack sites in the prepared samples by visual inspection. Hardness tests were also performed to determine the microhardness of the prepared hardfaced layers. Abrasive wear resistance tests were carried out on each prepared sample to determine their relative abrasive wear resistance relative to the reference material, abrasion resistant heat-treated steel having a nominal hardness of 400 HBW. The effects of the variations of PGFR and plasma arc current on the microstructure and mechanical properties of the coatings, and the wear mechanisms were discussed.