Resaerch Of Laser Cladding Performance Of Ni-base Alloy Engine Blade

K417G nickel-base superalloy was employed at aero engine turbine blades and guide vanes. The pores and porosity is easily produced in the process of casting during casting engine turbine blades, and the engine turbine blades with defective will be discarded and re-melted melting. If the defects in the engine turbine blade that produced during casting can be repaired by laser cladding method, it makes the engine turbine blades can work as no defective turbine blades, the investment can be greatly reduced and the economic benefit can be improved. In this research, the fiber laser is employed to clad the Nickel based alloy powder RCF-201 on the K417 G nickel-based alloy plate. The paper researches the forming process, microstructure and properties of the cladding layer. And the study provides theoretical and practical basis for the laser repair of the K417 G nickel based alloy turbine blades.This paper researches the width, height, depth, and the dilution rate of the cladding layer by changing the laser power P, scanning speed V, powder feeding rate v and the defocusing distance. The optimal process parameters of the laser cladding were determined. The shape,microstructure, phase composition and crack of the cladding layer, which is obtained by the optimum process parameters, is studied by optical microscope(OM), scanning electron microscope(SEM), energy dispersive spectrum(EDS) and X-ray diffraction(XRD); The creep life time of cladding layer was tested by creep test machine during high temperature, and the fracture morphology was observed. The hardness of the cladding layer was measured by Vickers hardness tester.The research obtained the optimum parameters of laser cladding, which are laser power400 W, scanning speed 10mm/s, powder feeding speed 15g/min, defocus amount 0mm,protective gas Ar flow 25L/min, powder gas flow 2.0L/min and the specimen preheated temperature ≥200°C. The structure of cladding layer is the sub eutectic structure, and the primary crystal phase is rich Ni solid solution ?-Ni, and the eutectic structure is composed of?-Ni+Cr7C3+Cr23C6+(Mo0.54, Ti0.46)C. The hardness of base metal is 330~350HV, and the hardness of the cladding layer is higher than that of base metal, reached to 635~660HV which is double times base metal. Under the condition of 950°C/235 MPa, the creep life time of the cladding layer is equal to the base metal about 26.17 h and the fracture position is located at thebase metal. The results of the fracture and cracks morphology analysis show that the fracture belongs to the intergranular crack during high temperature creep.