Pure niobium billet can be forged, extruded, rolled and drawn at room temperature ~ 500℃. The strength of niobium alloy is high, so generally in 1200℃ above extrusion and forging, and other primary processing, and then in 500℃ below extrusion, forging, rolling and other methods to produce bars, plates, strips, foil, pipes, wire and profile products. The grain size of niobium alloy ingot obtained by smelting is large, and the finished product can be processed only after crushing it by extrusion. To fully crush the large as - cast grains, the extrusion ratio is generally not less than 4. The interstitial elements oxygen, nitrogen and hydrogen, especially oxygen, react easily with niobium alloy at high temperature.
After alloy oxidation, not only loose oxide skin is formed on the surface, but also hard permeable layer can be formed by oxygen penetrating into the alloy matrix, which makes plastic processing difficult. Therefore, measures such as metal cladding, coating or inert gas protection heating must be taken in the process of extrusion and other hot working of niobium alloy.
Niobium alloy, especially pure niobium, is easy to bond with the mold in the drawing process, so anodic oxidation treatment must be carried out first to make the surface of the workpiece to form a compact oxide film and use lubricant.
Niobium and niobium alloy are easy to wear and bond tools, so when cutting with oil-water emulsion, carbon tetrachloride and other organic solvents cooling and lubrication, while keeping the sharp tip. When niobium and some niobium alloys are machined, the workpiece is easily bonded to the tool and the surface oxidizes. Low speed cutting and cooling liquid cooling should be used.
