Abstract: In order to obtain better combination scheme of process parameters of single cladding layer with high surface quality, a new forming method of “coaxial wire feeding inside three beams” is used. Mathematical model of relationship between process parameters of layer cladding and the surface morphology is established, between process parameters and geometric characteristics. The surface morphology state of cladding layer is judged by the ratio between the unit energy density provided by the laser E₁ and the required energy density of wire E₂.The mathematical model of the relationship between the process parameters and the geometric characteristics of cladding layer is used to predict the variation law of the geometric characteristics, and the single factor test method is used to make experimental verification. The experienced state of cladding layer surfacemorphology is that:E₁/E₂< 1, the molten pool energy is “insufficient”,1.1≥E₁/E₂≥1.0, the energy of molten pool is in the transition stage from “insufficient” to “sufficient”, E₁/E₂> 1.6, the energy of the molten pool is “excess”, the surface quality of the coating formed in these three cases is poor. Only when 1.5≥E₁/E₂>1.1, the “sufficient” energy of the molten pool can fully melt the wire, which can be melted into the molten pool in a continuous and stable way, the surface of cladding layer is continuously smooth and the quality is high. The variation law of cladding layer geometric characteristics: the predicted value of the mathematical model is in good agreement with the experimental value, the defocusing amount decreases, the width W decreases, the height H increases, and the ratio of width to height α decreases. Laser power increases, the width W increases, the height H decreases, and the ratio of width to height α increases. Scanning speed increases, the width W decreases, the height H decreases, and the ratio of width to height α increases slightly. Wire feeding speed increases, the width W and height H increases, and the ratio of width to height α decreases. Conclusion is that: make laser cladding test of stainless steel 304 wire and substrate by using new forming method of “coaxial wire feeding inside three beams”, selecting reasonable process parameters scheme, which meet 1.5≥E₁/E₂>1.1, better surface morphology can be achieved.

Key words: laser cladding, three beams, wire feeding inside beams, process parameter, geometric characteristics