Reinforcement mechanism and wear resistance of Al2O3/Fe-Cr-Mo steel composite coating produced by laser cladding

The nanometer Al2O3 dispersion strengthened Fe-Cr-Mo composite coatings by crosscurrent CO2 laser on 316L steel were produced. The microstructure and phase composition of the coatings were examined through optical microscopy and X-ray diffraction analyses. Hardness distribution, tensile properties and wear resistance of the coatings were determined to analyse the mechanical properties and the strengthening mechanism of the cladding layer. Results showed that Al2O3 was partly dissolved, and produced Fe3Al intermetallic compound; this new phase and Al2O3 feature fine grain, high hardness, high tensile strength, and excellent wear resistance. Fe-Cr-Mo steel with 8 wt.% Al2O3 was considered appropriate for uniformity of the microstructure. Under the same proportion with micro-Al2O3, the nano-Al2O3 was easily melted and generated Fe3Al. Improved hardness and wear resistance could be ascribed to the high bonding strength of Al2O3 reinforced phase to the matrix through the transition of Fe3Al intermetallic compound.219