The geometric accuracy deviation of the titanium alloy rod is mainly caused by the elastic problem of the material. Thermal forming of titanium alloy rods has poor inner and lower plasticity, high deformation resistance, and serious spring back, so forming problems are difficult and geometric accuracy is low.
The thermal forming of titanium alloy rods greatly reduces the distortion and spring back of the formed parts due to the soft ratio of high temperature to the material, but the spring back cannot be completely eliminated. Such as resistance heating press forming or stroke forming of titanium alloy rods. There is still a small amount of spring back after hot forming, and the geometric accuracy does not meet the quality requirements listed, so heavy manual trimming must be carried out.
GR5 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, automobile, and pharmaceutical sectors. During the thermoforming process of GR5 titanium alloy, a layer of oxide skin will be formed on the surface, and the color of the oxide skin obtained is different with different thermoforming temperatures. Among them, when the thermoforming temperature is about 600°C, the scale is blue; when the thermoforming temperature is about 850°C, the scale is grayish reddish; and when the thermoforming temperature is 900°C, the scale is gray. With the increase in temperature, the difficulty of oxide scale removal gradually increases. Most of the removal of titanium alloy scale at home and abroad adopts a two-step method, that is, molten alkali washing first, and then pickling; however, the temperature of the molten alkaline washing medium is relatively high, which can reach about 450 ° C, and it is easy to cause semi-finished products of α + β and β titanium alloys. Premature aging strengthens, which brings difficulties to further processing. In addition, cleaning with nitric acid and hydrofluoric acid after hot alkali cleaning may also cause hydrogen embrittlement corrosion on the surface of titanium alloys.
