Creep feed grinding of γ-TiAl using single layer electroplated diamond superabrasive wheels

The paper details machinability experiments involving creep feed grinding of Ti-45Al-2Mn-2Nb +0.8%vol. TiB2 intermetallic alloy using single layer electroplated diamond grinding wheels. A wheel speed of 35 m/s and a feed rate of 150 m/min were utilised along with two different grinding regimes; roughing with D252 and D126 wheels using a 1 mm depth of cut and finishing using a D46 wheel and 0.1 mm depth of cut. The roughing operation employing the D252 wheel gave a maximum G-ratio of ~100 and a workpiece surface roughness of 2.94 µm Ra. These reduced to ~20 and ~0.3 µm Ra using the D46 wheel. Normal and tangential forces when roughing were up to 2500 and 500 N respectively. Grit pullout was mainly visible with the D252 wheel however; wear flats were evident with all three wheels. Workpiece surfaces produced using the D126 wheel showed burn levels increasing with material removed. Analysis of surfaces generated with the D252 wheel showed the presence of cracks and pullout/fracture with a width of up to 50 µm and depth of 20 µm, whereas finishing conditions resulted in understandably superior surface integrity with no visible damage. Similarly, a hardened layer of up to 625 HK and extending to a depth of ~100 μm was apparent when roughing but was absent during finishing.