Evaluation of Workpiece Surface Integrity Following Point Grinding of Advanced Titanium and Nickel Based Alloys

Experimental results are presented following point grinding of Ti-6Al-4 V, gamma-TiAl and Udimet 720 nickel based superalloy using plain 15 mm diameter electroplated superabrasive (CBN and diamond) wheels employing 46 μm grit. Surface roughness (Ra) was typically higher by up to ∼36% on Ti-6Al-4 V due to greater wheel wear and workpiece smearing/re-deposited material, corresponding to significant levels of wheel loading. While Udimet 720 exhibited minimal variation in microhardness parallel to the feed direction, strain hardened surfaces of up to ∼100 HK0.025 above the bulk value were observed for γ-TiAl. In contrast, ground Ti-6Al-4 V workpieces showed minor softening at the surface. Sub-surface microstructural deformation was evident in both the Ti-6Al-4 V and γ-TiAl samples, which extended to a depth of ∼10 μm.