The processing method of small specification high strength niobium-hafnium alloy bar includes the following steps: 1. Niobium-hafnium alloy billet is sawed and blanked, and coated with anti-oxidation protective lubricant after heating; Two, upsetting forging, bar blank; Three, turn, grinding and the first vacuum annealing; Four, heating, coated with anti-oxidation protective lubricant after die forging forming, forging blank; Five, successively turning, grinding and second vacuum annealing; Six, pass rolling, get small size bar blank; Seven, straightening, peeling, polishing, pickling and finished product annealing treatment, to obtain small specifications of high strength niobium hafnium alloy bar. The cross section diameter of the bar obtained by this processing method is 8mm ~ 20mm, the tensile strength at room temperature is above 465MPa, the yield strength is above 350MPa, the elongation is above 47%, and the grain size is fine and uniform.
Niobium hafnium alloy belongs to the low strength series niobium alloy, which can be processed into various shapes, such as high performance rocket engine radiation cooling thrust chamber and nozzle extension structural parts. Niobium hafnium alloy has poor oxidation resistance in high temperature environment, so protective measures must be taken when using it. After adding protective coating, the service temperature can reach 1400~1500°C, which is the preferred material for large-scale use of liquid rocket engine nozzle. With the development of aerospace technology, niobium alloy material performance, use environment and other requirements are more and more strict, niobium alloy strengthening development direction mainly has two: one is to develop new alloy, such as niobium-tungsten series alloy developed by western developed countries, can increase the material temperature to 1650°C; The other is to improve the preparation method and processing technology of the existing alloy to improve the comprehensive properties of the material.
Niobium hafnium alloy is mainly prepared by electron beam smelting and arc smelting. Because the ingot grains after arc smelting are larger, grain breakage is generally carried out by extrusion. However, due to the limited capacity of the extrusion equipment, the selected extrusion ratio is usually small and the grains cannot be completely broken, so late forging or further extrusion is often required.
