Preparation And Properties Of Laser Modification Coating On SCH13 Steel

Laser cladding is one of the effective ways to improve the materials properties. The components performance and the service life can be greatly improved and prolonged by choosing the proper surface alloy material and laser cladding technique to obtain a good performance of abrasion-resistant and corrosive resistant cladding coating in the component failure surface which has a metallurgy union structure with the substrate, as a result the above process can get economic and social benefit. Alloy cladding coatings are prepared on SCH13 steel surface by using self-made CoNiCrAlY and CoNiCrAlY + Y2O3 alloy powders. The microstructure, chemical composition, microhardness, wear-resisting property of the coatings have been investigated by using scanning electron microscope, energy spectrometer, X-ray diffraction, microhardness tester and ball-on-disk wear tester.The testing results indicated that the CoNiCrAlY + Y2O3 cladding coating has fine microstructure and good property Take the powder as the research object, the optimized laser cladding parameters, which have been obtained by orthogonal experimental, are as follows: the laser output power is 1000W, scanning speed 6.6mm/s, facula diameter 2.5m. The laser parameters on the microstructure and properties of coating were studied in the mean while. Increasing the laser scanning speed and decreasing the laser power the width of the laser cladding coating become narrower, the microstructure of the laser cladding coating become finer, the microhardness become increased. The laser cladding coating has high microhardness because of the fine microstructure, the microhardness in surface is a little lower than subsurface due to the burning of alloy elements in surface.In order to obtaining large laser cladding coating, overlapping experiments is made by adopting different overlapping coefficient. The results demonstrate that when overlapping coefficient is 0.5, the maximum thickness difference of the coating is smallest, and the smoothness of the coating surface is the best, thus providing the basis for obtaining large cladding coating and industrialized application. The interface temperature gradient decrease attribute to the substrate temperature increasing,. As a result, the microstructure in overlapping laser cladding coating was coarser than single laser cladding coating. the microstructure results show that the laser cladding coating are mianly consist ofγ-Co, FeCr0.29Ni0.16C0.06, (Fe,Ni), CoCx and Cr23C6 phases, and there are a little kernels which are ricn of Y and Al. The microhardness of overlapping laser cladding is lower than single laser cladding coating. The microhardness of the overlapping laser cladding coating can reach HV600~700, that was 3 times more than the SCH13 steel substrate. The relative wear resistance was 4.42 times higher than that of the SCH13 steel substrate.