Niobium alloys are usually hot processed at or slightly above the recrystallization temperature. For different industrial alloys, typical processing temperatures are 1000-1350°C, and both forging and extrusion methods can be used. For smaller niobium ingots, extrusion or hammer forging are better methods; conventional pressure forging can cause the temperature to drop too quickly. Compared with other more common materials such as steel or titanium alloys, niobium alloys have higher flow stresses at hot processing temperatures, which can produce very large stresses on metal processing tools. For example, due to severe corrosion of extrusion dies, they can usually only be used once and must be replaced. During the hot working process, the surface of all niobium alloys is contaminated due to reaction with air. This layer of contamination is very brittle and must be removed mechanically or by grinding before subsequent cold working. The second processing method is to warm or cold process into the final shape through appropriate annealing steps, and the annealing is performed under high vacuum. Most industrial alloys are ductile enough to be rolled into strips, foils, rods, wires and tubes in various rolling mills, often with cold reduction reductions in excess of 70%.
Niobium alloys can be rolled into products of various complex shapes. The forming process is basically the same as that of all other ordinary metals, such as closed die forging, spinning, hydroforming, welding, etc. Closed die forging and a thinning spinner Pressure rocket injector. Niobium alloys often receive more attention than other high-temperature resistant alloys molybdenum, tantalum or tungsten due to their lower density and ease of processing.
Pure niobium has very good ductility, even under casting conditions. Unannealed niobium ingots can also be deeply cold worked (deformation degree exceeds 95%). Periodic annealing of the final product after multi-step cold working improves the Uniformity of grain size. Annealing temperature and cold working amount also have a comprehensive impact on the final grain structure. This level of high purity can reduce the recrystallization temperature to about 700°C, while the recrystallization temperature of industrial grade pure niobium is about 900°C.