Laser cladding has been attracting a great deal of researches in the past years, however, cracking evolved in laser cladding for large area coatings limits its practical industrial applications. A FeCSiB base metal matrix composite coating reinforced by carbide particles can be a good way to suppress cracking, since such a coating is composed of tough hypoeutectic FeCSiB matrix and dispersively distributed WC, TiC hard particles, which can ensure the good toughness of the cladded coating to endure the tensile stress induced in laser cladding.
In order to further eliminate cracks in large area cladding, the influence of processing techniques on cracking tendency on particulate reinforced metal-matrix composite coating was investigated in this paper. By introducing a method with reversed pre-deformation, preheating and postheating treatment at 450℃, large area clad coatings with optimized FeCSiB+Ti+Zr alloy powder on 12Cr2Ni4A component were achieved with smooth surface, low deformation and free of cracks under optimized processing parameters. Thus a coating is a kind of particulate reinforced metal-matrix composite with microstructure composing of typical austenite dendrites, the eutectic matrix and a large number of insitu hard phase particles.
This as-developed large area cladding technique has been successfully applied on the large area hardfacing of guide plates of a special engine. The engine test has proved that the particulate reinforced MMC coating has superior properties much better than the carburization process.