Objective: This study evaluated the grindability of a series of Ti-Al and Ti-Al-Cu alloys. Methods: Three binary Ti-Al (5, 6 and 7 mass%) alloys and six ternary Ti-Al (5 or 6 mass%)-Cu (1, 3 and 5 mass%) alloys were prepared in an argon-arc melting furnace, and were cast using a centrifugal casting machine (Ticast Super R, Selec) into magnesia molds (Selevest CB, Selec). Pure Ti, CP Ti and Ti-6Al-4V (Ti64) were used as controls. Two sizes of castings (n=2) were made (3.0mm x 8.0mm x 30.0mm; 3.5mm x 8.5 mm x 30.5mm) so that the second castings were the same size as the first after removal of the a-case. Grindability (n=8) was evaluated as volume loss (mm3) after abrasion using a SiC wheel (703-120, Brasseler) (100 gf) at 1250 m/min. The data were analyzed by two-way ANOVA (a=0.05). Results: The determined grindability [mean(S.D): mm3] are listed. Identical letters indicate no statistical differences (p>0.05).
Alloy | +a-case | -a-case | Alloy | +a-case | -a-case |
5Al | 2.74(0.80)ab | 2.41(0.43)abc | 5Al1Cu | 3.57(0.72)bcd | 3.47(0.88)cdef |
5Al3Cu | 5.73(1.09)e | 4.42(1.13)f | 5Al5Cu | 4.99(0.69)ef | 4.75(0.92)fg |
6Al | 3.27(1.08)bc | 3.02(0.75)bcde | 6Al1Cu | 4.75(0.83)def | 3.90(1.01)defg |
6Al3Cu | 5.09(0.97)ef | 4.35(1.02)ef | 6Al5Cu | 5.01(0.64)ef | 4.87(0.95)g |
7Al | 2.98(0.89)abc | 2.87(0.82)bcd | Ti64 | 4.28(0.76)cde | 3.71(1.08)cdefg |
Pure Ti | 1.83(0.70)a | 1.74(0.60)ab | CP Ti | 2.26(0.54)ab | 1.24(0.42)a |
The volume of the specimen with a-case removed tended to be greater than that of the specimen without the a-case. The volume of metal removed significantly increased with increases in Cu content (p<0.001). On the other hand, there was no significant difference in grindability among the three binary Ti-Al alloys (p>0.05). The volume of Ti-5Al+Cu and Ti-6Al+Cu removed was comparable to that of Ti-6Al-4V (p>0.05). Conclusions: The grindability of Ti-5Al+Cu and Ti-6Al+Cu was much better than that of CP Ti, due to their lower ductility resulting from the eutectoid component, a-Ti/Ti2Cu, which promoted effective chip formation. Partially funded by NIH/NIDCR grant DE11787.