Process parameter optimization and surface integrity evolution in the high-speed grinding of TiAl intermetallics based on grey relational analysis method

TiAl intermetallic alloy (Ti-45Al-2Mn-2Nb) is a typical hard-to-machine material which was used in the aero-engines. To study its machinability, the high-speed grinding experiments were conducted using electroplated diamond abrasive wheel. The effects of grinding parameters (e.g., grinding wheel speed v_s, infeed speed v_w, and grinding depth a_p) on the grinding force and temperature were discussed. Then, the grey relational analysis (GRA) and variance analysis method were utilized to analyze the results. In addition, the evolution of the surface integrity was researched to characterize the machinability comprehensively. The results show that a_p had the greatest effect on the normal grinding force and grinding temperature of TiAl intermetallics, while as for the tangential grinding force, v_s did. When v_s increases from 60 to 120 m/s, the residual stress along and perpendicular to the grinding direction decreased by 54.7% and 10%, respectively. The maximum microhardness of the ground surface increased to 620 HV_0.05 at this moment, which was 1.55 times larger than that of the original matrix. Additionally, the chips morphology indicated that the adverseness of the low temperature plasticity of TiAl intermetallic alloy could be well overcome through the high-speed grinding tests. Finally, according to the GRA, the combination of v_s=90 m/s, v_w=0.5 m/min, and a_p=0.1 mm was selected as the optimal parameter combination.