Corrosion and wear protection of AISI 4140 carbon steel using a laser-modified high-velocity oxygen fuel thermal sprayed coatings

Abstract

Inconel and micro and nano WC-12Co powders were deposited on AISI 4140 carbon steel by high-velocity oxy fuel (HVOF) coating and followed by laser surface modification. Laser power and scan speed were varied at different levels. Microstructure and microhardness were investigated. Nanocoatings performed better than microcoatings. Nanostructured WC powder coatings exhibited greater hardness compared to microstructured powder coating. When the laser power is increased to 170 W, a small cellular dendrite microstructure through multiphase solidification is formed due to the difference in thermal properties of Inconel 625 and WC particles. Adequate laser power and low scan speed were preferred to produce a high-quality coating. From the electrochemical corrosion test results, it was observed that the corrosion rate of laser-modified HVOF sprayed coating is lower than the carbon steel sample. This shows that the Inconel sprayed by laser-modified HVOF coating enhanced the corrosion resistance of the substrate steel material. The porosity percentage was higher for all the samples when laser scan speed was increased.