The Development Of WC-Co Cemented Carbide Friction Stir Welding Tool

WC-Co cemented carbide is one of the most widely used cemented carbide,however, the low strength, poor toughness and high processing difficulty greatlylimits its development, especially complex shaped carbide products such as frictionstir welding (FSW) tool are generally with high costs or poor performance.In order to meet the requirements of FSW with WC-Co cemented carbide tool,study on the alloy composition, vacuum sintering process and processing moldingprocess separately, with the aid of analysis and testing equipment includes rockwellhardness tester,micro hardness tester, universal testing machine, X-raydiffractometer and scanning electron microscope (SEM), contrastive analysismicrostructure and mechanical properties with different Co content, differentvacuum sintering process, different powder compacting process by different moldingagent, and focus on exploring the machining technology without paraffinplasticizing.The results show that WC-8Co cemented carbide has better comprehensivemechanical properties under1400°C×1h vacuum sintering,which suitable for FSWtool; PVA forming agent has less vacuum dewaxing defects than PW, affected theperformance of sintered alloy, suitable for the powder forming agent; Using coldisostatic pressing process could effectively improve the performance indicators ofsinter, strength and toughness increase of about30%; Powder compact through1150°C×1h presintering could basically meet the demand of turning processing,optimization of cutting parameters could acquire better machining surface.With the process of powder granulation by PVA-mould pressing+cold isostaticpressing-vacuum dewaxing and presintering-turning processing-vacuum sinteringagain could acquire FSW tool which meet the requirements of size, its relativedensity>99%, the hardness>93HRA, bending strength>900MPa, fracturetoughness>11MPa·m1/2. Welding tests show that compared with traditional hightemperature alloy FSW tool, WC-8Co cemented carbide FSW tool could adapt to thehigher tool rotation speed and welding speed, which improve the welding efficiencyand reduce the tool loss.