Analysis of the difficulty in hot forming of titanium alloy rods
The deviation of the geometric accuracy of the titanium alloy rod is mainly caused by the elastic repetition of the material. Titanium alloy rods are hot-formed, with internal and external plastic union, large deformation resistance, and severe springback, so the forming is difficult and the geometric accuracy is low.
The hot forming of titanium alloy rods, the soft ratio of the high temperature on the material, greatly reduces the distortion and springback of the parts after forming, but the springback cannot be completely eliminated. Such as resistance heating drop-press forming or punch forming of titanium alloy rods. The field parts still have a small amount of springback after thermoforming, and the geometric accuracy meets the non-required quality requirements, and heavy manual trimming must be performed.
TC4 titanium alloy has a series of advantages such as excellent corrosion resistance, small density, high specific strength, good toughness and weldability, and has been successfully applied in aerospace, petrochemical, shipbuilding, automotive and pharmaceutical sectors. During the thermoforming process of TC4 titanium alloy, a layer of scale is formed on the surface. The temperature of the thermoforming is different, and the color of the obtained scale is also different. Among them, the scale is blue when the thermoforming temperature is about 600℃; the scale is reddish gray when the thermoforming temperature is about 850℃; and the scale is gray when the thermoforming temperature is 900℃. As the temperature increases, the difficulty of removing oxide scales gradually increases. At home and abroad, the removal of titanium alloy oxide scales mostly adopts a two-step method, that is, molten alkaline cleaning and then acid cleaning; however, the temperature of the molten alkaline cleaning medium is high, which can reach about 450 ℃, and it is easy to cause semi-finished products of α + β and β titanium The premature aging strengthening of the steel will bring difficulties to further processing. In addition, hot alkali cleaning and then cleaning with nitric acid and hydrofluoric acid may also cause hydrogen embrittlement corrosion on the surface of the titanium alloy.