Creep feed grinding of burn-resistant titanium (BuRTi) using superabrasive wheels

摘要

Following an introduction on the use of titanium alloys for aeroengine applications, results are presented on the creep feed grinding of a beta titanium alloy Ti-25V-15Cr-2Al-0.2C wt.% (BuRTi) using vitrified bonded superabrasive wheels in a fractional factorial experimental design. Despite a general perception to the contrary, the range of titanium alloys in use is wide encompassing different alphaear alpha, alpha/beta and beta designations, each with specific mechanical/physical properties. In terms of aeroengine use, there are seven or eight key alloys (or their equivalent) used globally with the trend for higher operating capability both in relation to temperature and stress level. In the experimental work, grinding forces were significantly lower with diamond; however, wheels employing CBN grits achieved the highest G-ratio (up to ~280) and lowest surface roughness (~0.73 μm of Ra). This was accompanied by workpiece smearing and surface burn, which was evident in the majority of tests using CBN. Additionally, workpiece softening was observed within the first 15 μm from the machined surface.