Hot processing, mainly forging, rolling and extrusion i […]
Hot processing, mainly forging, rolling and extrusion is the basic production method of titanium flange semi-finished products and products. In view of the fact that the structure of titanium flanges is highly sensitive to thermal processing technology, the correct selection and mastery of process parameters is not only very important to ensure the accuracy of product dimensions, but also a key factor for the internal quality of the product.
Compared with general metal structural materials, the hot working characteristics of titanium flanges are large deformation resistance and narrow deformation temperature range. Titanium with hexagonal crystal structure is not easy to deform. In order to improve plasticity, it is necessary to heat the metal to the b-phase region above the transformation point for so-called b processing. However, due to the tendency of titanium flange to overheat, high temperature heating will cause the b crystal grains to grow rapidly. However, if the deformation is insufficient, the formation of coarse Widmanstatten structure after cooling will significantly reduce the alloy's periodicity and fatigue strength, and this kind of overheating The organization is difficult to eliminate in the subsequent heat treatment. Therefore, the current production does not require the critical point Tb to exceed the critical point Tb for the finished product or the thermal processing start temperature of the previous fire. Since the deformation resistance of the titanium flange is very sensitive to the decrease of the deformation temperature or the increase of the deformation rate, the stop forging temperature cannot be too low. The constraints of these two factors limit the processing temperature range of most titanium flanges to between 800 and 950°C, which is not easy to master. However, for the billeting of the ingot, the temperature range can be expanded to 850 to 1150°C, and the temperature will be gradually reduced during the subsequent fire processing.
Titanium flange alloy has poor thermal conductivity. During rapid deformation, the temperature of the core of the workpiece rises quickly, and it is easy to cause overheating due to slow heat transfer. The surface temperature of the workpiece is low, and surface cracks are easy to form. Therefore, pay attention to the deformation during processing. Speed and deformation.