Effect of Cr on wear resistance and mechanism of preset-powder laser cladding T15 alloy steel coating

Remanufacturing worn parts by the laser cladding process has wide prospect. To repair the worn camshafts, the T15 alloy steel coatings with different content of Cr were fabricated by the preset-powder laser cladding (PPLC). The effect of Cr content (3, 6, 9 and 12 wt%) on the microstructure and the wear resistance of T15 alloy steel coatings was investigated from the aspects of solution element, grain size and phase composition. The results indicate that the microstructure of the coatings is composed of martensite, retained austenite (RA) and eutectic boron-carbides. The content of martensite increases first and then decreases, the content of RA decreases and the content of eutectic boron-carbides increases with the increment of Cr content. The wear resistance increased first and then decreased with the increment of Cr content, the T15 alloy steel coating with the 9 wt% Cr has the hardness of 880 HV0.2, exhibiting the lowest wear rate (2.85 × 10−8 mm3/N·mm). A modified relationship between the wear rate and the Cr content is built by the nonlinear fitting method based on the classical Archard wear mode, the fitted results showed that the T15 alloy steel coating with 10.04 wt% Cr content has the highest wear resistance, which can provide a reference for the composition optimization of high speed steel with desired wear resistance.