Failure mechanisms of a whisker-reinforced ceramic tool when machining nickel-based alloys

Abstract

Cutting behavior and failure mechanisms of the SiC-whisker-reinforced Al 2O 3 ceramic cutting tool JX-1 in turning nickel-based alloys have been investigated in comparison with those of other kinds of ceramic and carbide tools. The resistance to depth-of-cut notch wear of the JX-1 has been found to be greater than that of other Al 2O 3-based ceramic tools because of the toughening effect of the whiskers, and its higher nose and flank wear resistance than that of Sialon tools has been attributed to its better chemical stability. Wear and fracture mechanisms have been studied in terms of microstructure, mechanical and chemical properties and thermal shock resistance of tool materials. Take the machining of a nickel-based alloy GH169, for example. At lower cutting speeds (<125 m min −1), tool life is restricted by depth-of-cut notching to which attrition and adhesive mechanisms mainly contribute. As cutting speed increases, flank wear and nose wear play important roles in determining tool life, while diffusion takes place in the cutting process. When machining at higher speeds (>180 m min −1), catastrophic fracture of the edge due to plastic deformation may occur. Similar results were obtained when machining GH761 and GH49. It is also found that cutting fluid influences the high-speed cutting behavior of JX-1 to a great extent.