Study On Microstructure And Properties Of Laser Remanufactured Fe-based Alloy Cladding Layers On H13 Die Steel

Research on improving service quality and service life of steel surface has become a hot topic in die industry.However,the service environment of molds is bad and complicated which lead various forms of failure,among which the proportion of surface wear failure is the largest.In this dissertation,laser remanufacturing?laser cladding technology and laser shock peening technology?was used to prepare pure Fe-based alloy cladding layer on H13 mold steel surface,WC-Fe composite cladding layers with different WC contents and M2-Fe composite cladding layers with different M2 high speed steel powders were fabricated as well.The macroscopic morphology,phases,microstructure,microhardness and friction and wear properties of each cladding layer were studied,and the wear mechanisms of different worn surfaces were explored.In addition,the effects of laser shock peening on the microstructure and friction and wear properties of pure Fe-based cladding layers were investigated,as well as the effects on the friction and wear properties of the remaining composite cladding layers.The specific research contents and conclusions are as follows:?1?Pure Fe-based alloy cladding layer was prepared on the surface of H13 die steel by using Fe104 powder,and the surface was subjected to laser shock peening treatment.The results show that the Fe-based cladding layer and the matrix exhibit good metallurgical bonding,and the macroscopic quality is good,with no obvious defects.The main phases are?-Fe,?-Fe,M₂₃C₆,M₇C₃,M2B,etc.The internal microstructure is mainly composed of dendritic and interdendritic network structures,in which Fe and C elements are widely distributed in the cladding layer,while Cr,Ni,Mo,and Si have a phenomenon of aggregation in the intergranular network.The average microhardness of the surface hardness of the cladding layer reached 644.5 HV,which was 24.1%higher than that of the substrate.The surface of the cladding layer had a lower friction coefficient and wear rate than the substrate,and the wear resistance was greatly improved.Different from the surface of the substrate,which is mainly adhesive wear and accompanying spalling wear,the wear mechanism of the Fe-based cladding layer is mainly abrasive wear but only accompanied by slight peeling wear,but it is accompanied by different degrees of oxidative wear.Laser shock peening results in complex structures such as dislocations and twins in the Fe-based cladding layer,which refines the grains and reduces the wear rate by 14.1%in terms of friction and wear properties.?2?Wc-Fe composite cladding layers were prepared on the surface of H13 die steel by adding 3%,6%,9%mass of pure WC particles to the Fe104 alloy powder,and laser shock peening?LSP?was applied to the three surfaces.The results show that the main phases in the cladding layer are still?-Fe,?-Fe,M₂₃C₆,M₇C₃,etc.The microstructure of each cladding layer is similar to the Fe-based cladding layer without WC particles.But with the WC content increasing,the internal hardness of Fe₃W₃C and Fe₆W₆C is gradually increased.The presence of WC particles contributed to the refinement of the microstructure.The average surface microhardness of the surface is increased by 1.5 HV,15.5 HV and 34.7 HV,respectively.The wear rates of different layers were reduced by 0.36%,20.4%and 35.8%respectively.When WC particles are added,the wear mechanism of the surface of the cladding layer with different WC content is still mainly abrasive wear,but with the increase of WC content,the accompanying adhesive wear and spalling wear are gradually reduced,and the oxidative wear scar is gradually intensified.In addition,the laser shock peening had a improvement when the WC content is 3%,but the amplitude is smaller than that of the cladding layer without WC treated by LSP.?3?M2-Fe composite cladding layers were prepared on the surface of H13 die steel by adding 5%,15%,25%mass of M2 high speed steel alloy powder to the Fe104 alloy powder,and laser shock peening?LSP?was applied to the three surfaces.The results show that the diffraction peak of?-Fe is significantly enhanced after the addition of the M2 high-speed steel powder,indicating that the amount of retained austenite is increased and the number of internal toughness phases is increased.More MC and M₆C and less M₂C and other high hardness phase appeared.With the increase of the proportion of M2,the degree of refinement of the microstructure in the cladding layer is improved,and the average microhardness of the surface is increased by 6.2 HV,32.2 HV,71.2 HV,respectively,compared with the Fe-based cladding layer without M2 added.When the content of M2 is 15%,the surface wear rate is less than that of the Fe-based cladding layer without M2 addition.The wear mechanism is mainly abrasive wear,and it has the best wear resistance among the three cladding layers.When the M2 content is 5%,the wear mechanism is mainly abrasive wear accompanied by severe spalling wear.When the M2 content is 25%,the wear mechanism is mainly abrasive wear accompanied by fatigue wear.In addition,LSP makes the wear resistance of the M2-Fe composite alloy cladding layers with different M2 ratios improved to a certain extent and effectively inhibits the fatigue wear on the surface of the specimen,but the wear mechanism of the three cladding layers was still dominanted by abrasive wear with varying degrees of adhesive wear and oxidative wearThe test results not only provide technical support for the improvement of the surface properties of H13 die steel,but also improve the friction and wear properties of other cold forging dies,stamping dies and other types of surface wearable die steels.The application provides a certain theoretical guidance,and has great theoretical value and practical practical significance for promoting the application of laser cladding technology and laser shock peening technology in practical industrial production.