Investigation on the high feed milling of M28

Abstract

Abstract The outstanding combination of high strength, fracture toughness and low mass makes the metastable β titanium alloy an ideal material for aviation application. Machining of the metastable β titanium alloy remains a challenge due to their poor machinability. In this study, the high feed milling of a novel metastable β titanium alloy M28 is investigated to evaluate the performance of a potential high-efficiency-machining approach for the next generation titanium alloy and promote the understanding of high feed milling. The cutting force and the wear mechanism of carbide tool coated with TiAlN-Al2O3 are investigated as well as the influence of high feed on machined surface microstructures and microhardness. Due to the chip thinning effect of high feed milling, a proper high feed maintains a sufficient chip thickness to prevent the ploughing. Cutting edge degeneration induced by the carbide matrix fracture accelerates the tool wear. Mechanical stress induced cracks lead to the uneven delamination of the TiAlN-Al2O3 coating. Slight effect of high feed can be found on the microstructures and microhardness of the machined surface. While the tool wear leads to significant grain fragmentation and distortion at the surface. Since no white layer is found in the cutting of M28, high feed milling shows the advantage of preventing the heat induced surface injury.