However the strengths of titanium alloys fall off rapidly at temperatures above 800 F, and their coefficients of expansion are even less than that for steels. These unusually poor thermal properties account, to a large extent, for the difficulties in machining titanium. These allotropic forms of titanium are known as alpha and beta respectively. Alloying elements favor one or the other. It also increases the metal's elevated temperature strength level chromium, iron, molybdenum, manganese and vanadium lower the transformation temperature, thereby making the beta phase stable at a lower temperature.
Titanium alloys fall into three classes, depending on the structures present.
In addition to the alpha and beta phases described in the preceding paragraph, there is also an alpha-beta phase that includes most of the titanium alloys now in use. In fact, it's considered the workhorse titanium alloy and is available in all product forms. Its density is 0.160 pound per cubic inch. This is particularly so once tool wear begins. Sharp tools should be employed at all times and should be replaced before they dull.