Effects of Cr addition on grindability of cast Ti–10Zr based alloys

Abstract

The present study was undertaken to investigate the microstructure, microhardness and grindability of a series of cast Ti–10Zr– xCr alloys with 1, 3, 5, 7 and 10 wt.% Cr. The grindability of Ti–10Zr and Ti–10Zr– xCr alloys was evaluated by measuring the amount of metal volume removed after grinding for 1 min at each of the four rotational speeds of the wheel (500, 750, 1000 or 1200 m min −1), with the goal of developing a titanium alloy possessing superior grindability than commercially pure titanium (c.p. Ti). The results indicate that the structure of Ti–10Zr– xCr alloys is sensitive to the Cr content. With Cr contents higher than 3 wt.%, the equi-axed β phase began to be retained, while ω phase was found in the Ti–10Zr–3Cr, Ti–10Zr–5Cr and Ti–10Zr–7Cr alloys. The largest quantity of ω phase and the highest microhardness values were found in the Ti–10Zr–5Cr alloy. The grinding rates of the Ti–10Zr based alloys showed a similar tendency to the microhardness. The Ti–10Zr–5Cr alloy exhibited the best grindability, especially at 500, 750 and 1000 m min −1. Its grinding rate at 1000 m min −1 was about 2.6 times that of c.p. Ti, and the grinding ratio was approximately 2.7 times that of c.p. Ti. This study concluded that because Cr can not only harden Titanium, but also improve its grindability, the Ti–10Zr–5Cr alloy has a great potential for use as a dental machining alloy.