Laser produced functionally graded tungsten carbide coatings on M2 high-speed tool steel

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2001-04, Vol.302 (1), p.106-114
• Main Authors: Riabkina-Fishman, M, Rabkin, E, Levin, P, Frage, N, Dariel, M.P, Weisheit, A, Galun, R, Mordike, B.L
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; FGM; Laser alloying; Laser cladding; Metals. Metallurgy; Nonmetallic coatings; Production techniques; Surface treatment; WC functionally graded coatings
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/S0921-5093(00)01361-7

The objective of the investigation was to produce functionally graded, carbide alloyed multilayer coatings on M2 high-speed steel by laser alloying with direct injection of WC powder into the melt pool. Single layer coatings with a wide alloying range corresponding to 12–58 wt.% W and 1.3–4.3 wt.% C, respectively, were produced by varying laser beam power and beam traverse velocity. Depending on the alloying degree, four different types of structures were observed in laser alloyed coatings; they were characterized by scanning electron microscopy and X-ray microanalysis. Multiple laser alloying with beam power decreasing at each successive stage was used for producing a triple-layer coating with tungsten content increasing from layer to layer and reaching 75 wt.% in the upper layer. The observed hardness was in the 1100–1200 HV range for single layer coatings with 40–50% W and as high as 1600 HV in the upper layer of a triple coating with 75% W. The coating with 58 wt.% W showed wear resistance five times as high as compared with the unalloyed laser-melted M2 steel.