Abstract
High speed steel laser cladding coatings are complex because cracks appear and the hardness is lower than expected. In this paper AISI M2 tool steel coatings on medium carbon AISI 1045 steel substrate have been manufactured and after Laser Cladding (LC) processing it has been applied a tempering heat treatment to reduce the amount of retained austenite and to precipitate secondary carbides. The study of metallurgical transformations by Scanning Electron Microscopy (SEM) and Electron Back Scattered Diffraction (EBSD) shows that the microstructure is extremely fine and complex, with eutectic transformations and MC, M 2 C and M 6 C precipitation. Therefore, after the laser coating is necessary to use post-weld heat treatments.
Highlights
High Speed Steels (HSS) exhibit very high wear resistance combined with mechanical strength when proper heat treatment is applied
It is an ultrafine martensitic microstructure with secondary carbides dispersion mainly accumulated at border grains (Fig. 2 A))
According with Boccalini M2 eutectic transformation during solidification can be -M2C, -M6C or -MC depending on cooling rate, composition and maximum temperature[3]
Summary
High Speed Steels (HSS) exhibit very high wear resistance combined with mechanical strength when proper heat treatment is applied. They are very appreciated for cutting tool applications[1]. (ii) Peritectic reaction: ferrite + liquid austenite. (iii) Eutectic decomposition of residual interdendritic liquid: liquid austenite + carbides. Residual ferrite in the dendritic cores transforms to austenite and carbide, which is known as the ‘d eutectoid transformation’. The resulting as cast microstructure has a matrix with products from austenite decomposition (normally martensite and some retained austenite) and a network of eutectic carbides heterogeneously distributed in interdendritic regions[3]
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