Microstructure and Properties of Electromagnetic Field-Assisted Laser-Clad Norem02 Iron-Based Cemented Carbide Coating

An electromagnetic field-assisted (EMF-assisted) laser cladding technique was used to prepare Norem02 iron-based cemented carbide coatings on 304 stainless steels. The coatings then were characterized in terms of their microstructure, microhardness, residual stress, and wear resistance. The results indicated that EMF did not change the phase composition of the Norem02 iron-based cemented carbide coating, but significantly affected its microstructure and properties. EMF accelerated the formation of more uniform and refined microstructure. With an increasing current intensity of EMF to 40 A, the dendritic and columnar crystal structure of the coating gradually transformed into uniform and fine equiaxed grains. However, when the EMF current intensity was increased to 80 A, a small number of small dendrites and columnar crystals began to appear at the top and bottom of the coating. Accordingly, the microhardness first increased, then decreased, and achieved a max of 376.9 HV(0.2) at EMF current intensity of 40 A. EMF also improved the wear resistance of the coatings, reduced the cracking sensitivity, and reduced residual stress on the surface by 45.2%.