When extruding titanium and titanium alloys, the extrusion temperature is high and the extrusion speed is fast to prevent the temperature from dropping too fast. At the same time, the contact time between the high/temperature billet and the mold should be shortened as much as possible. Therefore, a new type of heat-resistant mold material should be used for the extrusion die, and the conveying speed of the billet from the heating furnace to the extrusion barrel should be fast. In view of the fact that metals are easily contaminated by gases during heating and extrusion, appropriate protective measures should also be adopted. When extruding, proper lubricant should be selected to prevent sticking to the mold, such as sleeve extrusion and glass lubrication extrusion. Due to the large deformation thermal effect of titanium and titanium alloys, and poor thermal conductivity, special attention should be paid to prevent overheating during extrusion deformation.
The extrusion process of titanium alloy is more complicated than that of aluminum alloy, copper alloy and even steel, which is determined by the special physical and chemical properties of titanium alloy. When the titanium alloy is formed by conventional hot reverse extrusion, the mold temperature is low, and the temperature of the surface of the blank in contact with the mold rapidly decreases, and the temperature inside the blank rises due to the heat of deformation. Due to the low thermal conductivity of the titanium alloy, after the surface temperature drops, the heat of the inner layer blank cannot be transferred to the surface layer for supplementation in time, and a surface hardened layer will appear, which makes it difficult to continue the deformation. At the same time, the surface layer and the inner layer will have a large temperature gradient, even if it can be shaped, it is easy to cause deformation and uneven structure.