Effect of laser energy volume density on wear resistance and corrosion resistance of 30Cr15MoY alloy steel coating prepared by laser direct metal deposition

Abstract

For laser repairing the wear and corrosion failure parts, the effect of laser energy volume density (EVD) on the wear resistance and the corrosion resistance of 30Cr15MoY alloy steel coating prepared by the laser direct metal deposition (DLMD) was investigated. The 30Cr15MoY alloy steel coating composed of martensite, retained austenite and grain boundary precipitates was fabricated, exhibiting good quality without cracks and pores. A good metallurgical bonding between the 30Cr15MoY alloy steel coating and the substrate formed, the element dilution from substrate to coating was slight. The wear failure of coatings is a combination of abrasive wear, adhesive wear and oxidation wear, the sample has the lowest wear rate (6.49 × 10−6 mm3/N·mm) and the highest micro-hardness (768 HV0.2) when the EVD is 128 J/mm3. The wear resistance of the 30Cr15MoY alloy steel coating is mainly related to the solid solution content, the grain boundary type and the phase composition. The main corrosion failure of the DLMD 30Cr15MoY alloy steel coating is the pitting corrosion, and the sample with EVD of 128 J/mm3 displays the best corrosion resistance (Icorr: 0.43 × 10−6 A·cm2, Ecorr: −217.40 mV). The content of grain boundary precipitates is the main determining factor of the corrosion resistance, and the Cr-depleted regions surrounding the grain boundary precipitates are the preferential sites of the pitting corrosion. Besides, the corrosion resistance is also related to the solid-solution content of C and Cr and the grain boundary type. It is expected that this study could provide new material and wear and corrosion resistance theories for laser repairing short stress line rolling mill and other mechanical parts.