CRACK CONTROLLING OF COMPOSITE COATING WITH NANO-METER NI-AL2O3 BY PULSED ND:YAG LASER CLADDING

摘要

Pulsed Nd:YAG laser is especially suitable for precision cladding on local region of steel, due to its high single pulse energy, various changeable parameters, short wavelength and flexible processing. Nano-meter composite coating is featured with high strength, good toughness, excellent wear resistance and erosion resistance. Composite coating was prepared by pulsed Nd:YAG laser with nano-meter Ni-Al2O3 on 3Cr13 stainless steel in this paper. However, because of very high heating and cooling rates and brittle ceramic phase of Al2O3, crack is prone to formed on cladding coating. This paper investigated the influences of varying laser parameters, different compositions of Ni and Al2O3, different degrees of overlap on the cracking in the cladding layers. The cause of crack forming was analyzed, and the processing parameters were optimized. The microstructure was observed by optical microscope (OM) and Scanning Electron Microscopy (SEM), the element distribution was analyzed by X-ray energy spectrometer (EDS), and the microhardness was measured by hardness tester.