Research On Deep Cryogenic Treatment And Cutting Performance Of WC-10Co Based Nanocrystalline Gradient Cemented Carbide

Resent years,more and more difficult-to-cut materials are widely used due to their excellent performance.However,serious cutting problems are gradually emerging.Difficultto-cut materials,except high-temperature structural ceramics,are most often processed with cemented carbide tools at present.Nanocrystalline cemented carbide and gradient cemented carbide are the focus of cemented carbide tools.With the combination of nanocrystalline and gradient structure,both of the advantages can be obtained in cemented carbides.Moreover,as an economical and environmentally friendly method,deep cryogenic treatment(DCT)can further improve the wear resistance and service life of the tools,which enables it to meet the stringent processing requirements of today’s difficult-to-cut materials.In this paper,the DCT process of Col0Ti2 nanocrystalline gradient cemented carbide were studied at first.Then the strengthening mechanism and the applicability of the DCT process of Co10Ti2 cemented carbide were studied in addition.Finally,the cemented carbide tools’ titanium alloy and stainless steel high-speed cutting performance and the wear mechanism before and after DCT were discussed.The results show that:(1)The best cryogenic treatment process of Co10Ti2 cemented carbide is:DCT 24 h and tempering twice at 300℃.After cryogenic and heat treatment,the hardness and saturation magnetization of Col0Ti2 nanocrystalline gradient cemented carbide increased,while the coercive force of the alloy reduced.The fracture toughness changes little,and there is no η phase formed during DCT.The strengthening mechanism is mainly reflected in the phase transition of Cobalt and the dissolution and dispersion of cubic phase.(2)After cryogenic and heat treatment,four kinds of nanocrystalline cemented carbide tools’ cutting performance improved,among which the Co10V2 and Co10TiC2 carbide tools performed better.When cutting TC4 titanium alloy,the flank wear of Co10V2 and Co10TiC2 carbide tools were less than that of YBG202 and GC1105 coated tools.When cutting 2205 stainless steel,the flank wear of Co10V2 and Co10TiC2 carbide tools were between that of YBG202 and GC4225 coated tools.(3)When cutting titanium alloy,the carbide tools mainly suffer adhesion wear.When cutting stainless steel,the carbide tools mainly suffer abrasive wear.In addition,both diffusion wear and oxidation wear are occurred during tools’ cutting.DCT can reduce the adhesion wear and diffusion wear of the carbide tools when cutting titanium alloy,and slow down the diffusion wear and oxidation wear of Co10TiC2 carbide tool when cutting stainless steel.