The Research On Laser Cladding Of High Entropy Alloys For Hot Work Die Steel

H13（4Cr5Mo Si V1）hot work die steel is a common die manufacturing material.In the service process,the die surface is prone to wear,erosion,pitting and other surface failure forms.Therefore,it is very important to improve the surface properties of die steel.In this study,FeCoCrNiAl high entropy alloy were prepared on the surface of H13 steel by laser cladding technology,and the coating properties were improved by adding WC hard phase,which has great significance to improve the service life of H13 die steel and save s metal resources.FeCoCrNiAl high entropy alloy coating and FeCoCrNiAl+x WC high entropy alloy composite coating were prepared on the surface of H13 steel by DL-HL-T200 high power cross flow CO₂ laser;The macro morphology,microstructure and phase composition of the coating were studied by optical microscope（OM）,X-ray diffraction（XRD）,scanning electron microscope（SEM）and energy spectrum analyzer（EDS）;The coating properties were tested by Vickers hardness tester and high temperature friction and wear tester.The change rules of coating structure and properties are systematically analyzed,and the specific research results are as follows:1.FeCoCrNiAl coating is composed of BCC and FCC solid solution,and the microstructure is mainly composed of fine equiaxed crystals and columnar crystal s.The hardness and wear resistance of the coating are significantly higher than those of the substrate,the main wear forms of the coating at high temperature are oxidation wear and abrasive wear,while the main wear forms of H13 steel are oxidation wear,abrasive wear and fatigue wear.The wear volume of the coating increases slowly with temperature,but the wear volume of H13 steel increases sharply with temperature.The refore the wear resistance of the coating at different temperatures is significantly better than that of H13steel.2.In the study of the effect of laser power on coating performance,It is found that the coating with laser power of 1.2k W has the best wear resistance,and the minimum wear volume is only 19.99%of the wear volume of the substrate.The coating is mainly composed of equiaxed crystal,the upper part of the bottom layer is composed of columnar crystal and equiaxed crystal;When studying the influence of scanning speed on the wear resistance of the coating,it is found that the coating with scanning speed of 300mm/min has the best wear resistance,and the minimum wear volume is only 19.37%of the wear volume of the substrate.3.The main phase structure of FeCoCrNiAl+x WC high entropy alloy composite coating is still composed of solid solution.Carbides were dispersed in the coating,and the maximum hardness of the coating is 600HV_0.1-900 HV_0.1,which is 2.7 times higher than matrix.The friction coefficient of the coating at 350℃is only 0.25,which is 54.55%lower than that of the matrix under the same parameters.The wear volume of the composite coating with different WC content has little change,and the wear volume of the composite coating with 10%WC content is the smallest,which is 20.24%of the wear volume of the substrate.Abrasive wear and oxidation wear are still the main wear forms of the coating.In conclusion,the coating prepared by laser cladding FeCoCrNiAl and FeCoCrNiAl+x WC alloy powder on the surface of H13 steel significantly improves the high-temperature wear resistance of the coating,further improve the service life of die steel.