The Application Of Laser Cladding Technology In The Repair And Remanufacturing Of Large Plungers

Hydraulic cylinder as a hydraulic actuator, through which the linear reciprocating motion (or swinging movement) can be achieved to the hydraulic can be transformed into mechanical energy, in a variety of hydraulic mechanical system has been widely used. Plunger type hydraulic cylinder in use often occurs leakage fault, if the leak is due to the plunger surface abrasion, scratching and corrosion, for reuse and surface repair work is essential. The repair of large piston synthesis methods are mostly confined to the casement, welding, thermal spraying, or their composite process (rinse) electric plating, the technology, although more mature, but also has a process of self short board. Laser cladding is small because of the process of heat affected zone, the deformation of the workpiece is small, high rate of finished products, cladding layer has a low rate of dilution, cladding metallurgy combination of characteristics, became the a model of remanufacturing surface modification technology. In this paper, the advantages of laser cladding technology is to study a large surface laser cladding process, so as to fill the gaps of the existing laser cladding repair.In this paper, by analyzing the process parameters influence on the cladding layer, considering the cladding quality, welding cladding efficiency, price, and other factors to determine the plunger surface to optimize the laser cladding process parameters:substrate: Forged Steel 40Cr; cladding materials:GM-122 backing+DL-155 (Hardcover); powder feeding mode:argon pneumatic synchronous powder feeding; preheating temperature:100 plus or minus 10 DEG C; laser power:3.5kw, spot diameter:3.0mm (positive defocus); overlap 1.5mm; scanning speed:500mm; powder feeding quantity:8.2g/min.Laser cladding surface morphology can be roughly classified as normal surface melting, critical surface melting and not fully melted surfaces, the critical surface melting and not fully melted surfaces are defects in laser cladding surface; normal melting of laser cladding layer to dendritic microstructure is the main, the organization fine uniform, grain size measured from 10 to 12 level; microhardness in the cladding thickness range hardness little ups and downs, hardfacing layer and grounding layer element inter diffusion is small, effectively ensure the molten layer design elements is not diluted, hardfacing of cladding layer can effectively retain pre design of alloy composition, and its excellent performance.There are uneven cracks, porosity, composition and surface morphology defect defect of laser cladding layer can be through a preheat and post heat treatment; the cladding layer; adding alloy elements; the baking of the cladding powder. When we add protective gas; it appropriate to reduce the scanning speed and powder feed rate etc. can inhibit the defects of cladding layer.The practical application of the large piston laser cladding repair shows that the cladding layer is firmly combined with the wear resistance and corrosion resistance. The research and development process has a certain range of application, can be used in the same type of material, the use of parts of the work condition of the surface of the part surface.