Wear Mechanisms Of Cemented Carbide Tools In Turning Of Semi-austenitic Precipitation Hardening Stainless Steel

At present, semi-austenitic precipitation hardening stainless steel has been used widely in the aerospace industry, especially in the skin of the aircraft because of the unique advantages. The research of oxidation and diffusion properties between cemented carbide tools and semi-austenitic precipitation hardening stainless steel was carried out, and the results were confirmed through turning experiment of semi-austenitic precipitation hardening stainless steel, thus the main wear mechanism of cemented carbide tools was obtained.The chemical thermodynamics computation and oxidation test on cemented carbide tools and semi-austenitic precipitation hardening stainless steel were studied, the results indicated that:the oxidation weightlessness of YT cemented carbide tools is less, so the anti-oxidation ability is stronger; the WC and Co in YG cemented carbide tools had already been oxidized in 1200K, but the TiC in YT cemented carbide tools had not been oxidized; the anti-oxidized ability of fine grain cemented carbide tools is better than that with coarse grains. So the preferential order of anti-oxidized ability on five cemented carbide tools is as follows:YT15>YT5>YG6X>YG6>YG8. The specimen of semi-austenitic precipitation hardening stainless steel was completely oxidized in 1300K, and the oxidation product of Fe, Cr, Mn and Ni is respectively Fe2O3, Cr3O8, Mn2O3 and NiO.The diffusion test from cemented carbide tools to semi-austenitic precipitation hardening stainless steel (vice versa) was studied. The results showed that:the diffusion had took place along the interface of the diffusion couple composed of cemented carbide tools and semi-austenitic precipitation hardening stainless steel in 200℃, and the diffusion degree was more violent with increasing temperature. Diffusing phenomena are quite obvious in 400℃, the diffusion degree in YT cemented carbide tools is more obvious than that in YG cemented carbide tools, and crystal grain of cemented carbide tools material is finer, the diffusion is more difficult. The Vickers hardness near the interface of the diffusion couple is lower than far away from the interface owing to element diffusion. So the size order of diffusion degree on five cemented carbide tools is as follows:YT15>YT5>YG8>YG6>YG6X.The turning test on semi-austenitic precipitation hardening stainless steel was carried out with cemented carbide tools. Results showed that:YT cemented carbide tools were more suitable for turning semi-austenitic precipitation hardening stainless steel than YG cemented carbide tools through analyzing tool flank wear, cutting force, surface roughness and cutting temperature. Oxidation wear, adhesive wear and diffusion wear were the main wear mechanism of YT cemented carbide tools; oxidation wear, boundary wear, adhesive wear and diffusion wear were the main wear mechanism of YG cemented carbide tools.