Abstract: Cobalt -base alloy layer was cladded on the T8 carbon steel surface by cross-flow-type CO₂ laser with different parameters; the phase constitution, carbide content and chemical composition, microhardness and wear resistance of the alloy layer have been determined by X-ray diffraction, electrolytic extraction, comparison colorimeter and microhardness tester etc. and the saturation of matrix alloy was calculated from lattice constant. It can be concluded that the saturation of r-(CoCr) matrix makes important contribution to the hardness and the wear resistance of the alloy layer, however, is improved greatly due to the M₇C₃ carbide content.

Key words: laser cladding, cobalt-base hardfacing alloy, phase constitution