Study On Indexable Cutting Tool With Ultraifne Cemented Carbide For Stainless Steel Cutting

Stainless steel is more widely applicated in the manufacturing and construction withgood corrosion resistance, formability and high chemical stability and so on. However,stainless steel material has certain difficulties for cutting because of toughness, low thermalconductivity, much cutting heat and dissipating heat difficultly. In the view of the difficultprocessing characteristics, high hardness, high strength and high wear resistance of ultrafinecemented carbide has been become an important selection.In this paper, Co and (W,Ti,Ta)C of different contents were doped in ultrafine cementedcarbides based on WC-6%Co and WC-8%Co. These ultrafine cemented carbides wereprepared in pressure sintering. The effects of (W,Ti,Ta)C multiple carbide content, Co content,grain growth inhibitors, sintering temperature were researched through these experiment onmicrostructure and mechanical properties of the ultrafine cemented carbides; and theperformance of coating and the experiment of coated tools were further studied.The results indicated that with the increment of (W,Ti,Ta)C, the bending strength and thecoercive force of cemented carbides decreased, but the hardness increased; As the content ofCo increased from6%to8%, the hardness and the coercive force of cemented carbidesdecreased, but the bending strength increased. The WC-8%Co-2%(W,Ti,Ta)C cementedcarbide which was prepared in pressure sintering at the temperature of1390℃had hardnessof93.4HRA, TRS of2670MPa, coercive of37.4kA/m respectively, after adding the inhibitorof0.5%(Cr3C2/VC), the comprehensive properties of the ultrafine cemented carbide had beenimproved. The density of alloys and the comprehensive properties of alloys can be increasedwith the sintering temperature increasing. CVD coating process was used to depositTiCN/Al2O3/TiN film on YG6and YG8cemented carbides substrates. the average thicknessof TiCN/Al2O3/TiN film was7-9μm and the surface of film had no obvious disfigurementthrough SEM observation, and XRD results indicated that there were matrix phase WC andcoating phase as well as Ti oxides. These experiments which using coated cemented carbidecutting tools to cut0Cr18Ni9austenitic stainless steel workpiece were carried out. Under thecutting speed of100m/min, the tool which the substrate was WC-8%Co-8%(W,Ti,Ta)C hadthe minimal blade wear and the maximum combination. The coated cemented carbide cuttingtools appeared the rake wear, flank wear, chipping as well as coating peeling. The reasons ofwear included mechanical wear, oxidation wear and mechanical stress and shock.