A Comparison of the Grinding of IMI318 Titanium Alloy and a Gamma Titanium Aluminide Intermetallic

This paper initially reviews the development of titanium aluminide and published grinding research on standard titanium alloys and titanium intermetallics. Experimental data is presented which compares the grindability and workpiece surface integrity of an unrefined gamma (γ) intermetallic with a standard alpha / beta (α/β) titanium alloy, Ti-6A1-4V (MI 318), using a conventional SiC wheel at 30m/s peripheral wheel speed. A G ratio value of approx. 1.5 was obtained for the standard alloy, with surface roughness measurements of 1.5µm Ra (0.8mm cut-off) rising to 2µm Ra after 200 passes. Forces were seen to rise from 50 to 300N over the period of the test. In comparison, the G ratio of the aluminide was above 40 with surface roughness measurements of 1.5 to 0.6µm Ra after 400 passes. Forces increased from 50 to 300N up to 200 passes, however, little further increase was noted over the next 150 passes before the onset of measurable wheel wear.