A Study Of Laser Cladding Gradient Wear-Resisting Coating Process

With the development of technology, the vehicle engine orient toward to the direction of small size, high speed, gradually increasing the load of mechanical transmission system, the existing parts surface strengthening methods, such as carburizing quenching, high frequency quenching process, have been unable to meet work requirements, appearing phenomenon of badly worn and low-life. Laser cladding can obtain the excellent coating(such as high hardness, wear resistance, corrosion resistance, etc.) from low-cost substrate surface. But as the load continued to expand, the cladding layer in low thickness also gradually lose its advantage in the work of process. It is more and more urgent to make a research to the laser cladding wear-resisting coating with high thickness and high hardness.This paper studies the process of preparing of the high thickness gradient wear-resisting coating using laser cladding in20CrMnMo steel surface. The step by step method of design, preparation and analysis is used to optimization the process parameters in the cladding process. The test and analysis to the macro-morphology, microstructure, microhardness, wear properties of various kinds of cladding layer have been made during the tests.The results show that:it can obtain toughness ground floor with good metallurgical combination in the matrix surface cladding St6alloy powder, using800W laser parameters of the laser power,10mm defocusing distance, the powder feeding speed of4.75g/min, the scanning speed of360mm/min, and lap rate of30%. Having no change of other parameters, but improving the powder feeding speed to6.45g/min, and cladding St12B alloy powder, can get high thickness of the transition layer in the ground floor. Using the underlying parameters to clad the alloy powder of Co47+5%ω(WC) in the transition layer, can get the wear-resisting layer with high hardness. The wear-resisting performance increase300%comparing with the carburizing hardened matrix.