Effects of ultra-high purification and addition of interstitial elements on properties of pure titanium and titanium alloy

Various properties of pure titanium and titanium alloys with ultra- high purity prepared by melting raw titanium made by improved iodide process have been examined. Effects of oxygen, nitrogen and carbon addition to pure titanium and SP-700 alloy on tensile properties were investigated, and strengthening effect and ductility variation due to these elements were evaluated. The strength of pure titanium and SP-700 alloy markedly decreased with the increase of purity, the yield strength of pure titanium containing oxygen of 40 ppm being reduced to 100 MPa. The recrystallization temperature of cold rolled ultra-high purity titanium was extremely low, 553 K, a small amount of oxygen and iron doping markedly increased this temperature.