A study of the abrasive wear behaviour of laser-clad tool steel coatings

A comparative study of the abrasive wear behaviour has been conducted on several tool steel coatings that were deposited by laser cladding process using a CW CO2 laser in combination with a blown powder feed technique. The laser-clad CPM 15V and CPM 10V coatings exhibit superior abrasive wear resistance as compared with the reference material, AISI D2 tool steel. In contrast, the wear resistance of the CPM 9V and M4 coatings is inferior to that of the D2 steel. As multiple overlapping clad-tracks are used to produce a coating covering relatively large area, a thin layer of a pre-deposited clad-track will be “over-heated” while depositing the next adjacent one. Depending on the coating material, this re-heated zone (RHZ) can exhibit different wear rate compared with the other area of the track in the as-clad condition, which is especially significant for the CPM 10V coating. For coatings with a large proportion of retained austenite, post heat-treatment promotes the transformation of the retained austenite to martensite, improving the wear resistance. The wear resistance of tool steel coatings is dependent upon the matrix microstructure and the features of dispersed carbides, such as their type, proportion, shape, size and distribution.