Effect of Alloying Element, Cr, on the Burning Behavior of Titanium Alloys

The alloys Ti-35V-15Cr(c) and Ti-25V-15Cr-0. 2Si(Ti40) exhibit good burn resistance, however, the influence of the alloying element, Cr, on alloy burning behavior is not clear. Effect of alloying element, Cr, on titanium alloy burning behavior is studied by means of the direct current simulation burn (DCSB) ignition method. The results indicate that the burn resistance is improved as the Cr content is increased beyond 10%, even more so beyond 15%. However, Ti-Cr binary alloys do not reveal burn resistant behavior. The reason is that the burned Ti-Cr alloy surface is porous and cracked, and the interface between burned product and the matrix is the same as it is when the Cr content is less than 10%, which is insufficient to retard oxygen diffusion into the matrix. But the interface of Ti-(>10)Cr alloys is rich in Cr, and the oxide film is tenacious and able to retard oxygen diffusion into the matrix thereby decreasing the burning velocity. The burned products of Ti-Cr alloys are TiO₂, TiO and TiCrO₃.