Plastic working---The plasticity of pure tantalum is good, the deformation resistance is small, the work hardening rate is small, all kinds of profiles and shaped parts can be obtained by plastic processing method. Pure tantalum can be rolled into sheet, strip, foil, tube and bar at room temperature, and the processing rate can reach more than 90%. In order to reduce oxidation, plastic processing of pure tantalum is often carried out at room temperature or below 500℃. Tantalum alloy due to high strength and poor plasticity of the ingot, must first be opened above 1200℃, after the processing technology is the same as pure tantalum. The extrusion ratio of the blank should be greater than 4, and the forging ratio should be greater than 2. When the billet is heated, it is necessary to prevent gas pollution and reduce the plasticity of the material. In order to ensure that the product has good stamping and spinning properties, it is necessary to use cross rolling. The processing rate before cross rolling should be maintained at about 80%. Tantalum sheet can be made into cups, caps, tubes, cones, nozzles and other parts with different shapes by spinning and deep drawing. The diameter of the rotary forging rod for wire drawing is generally 2.5 mm. Because the tantalum is soft and easy to bond with the mold and scratch the surface, the wire drawing surface is often anodized to form an oxide film and lubricated with beeswax.
Weld---The welding process of vacuum electron beam welding and inert gas tungsten electrode welding can produce welding parts with low plastic-brittle transition temperature. The welding tantalum tube produced by this welding process can meet the requirements of the chemical industry. Tantalum can also be welded together with stainless steel, titanium alloy, nickel alloy and carbon steel. Steel and tantalum can be combined into bimetal by high energy rate forming (explosion method), which is an effective method to manufacture large corrosion resistant equipment lining.
Cutting process---Tantalum and tantalum alloy are easy to wear and bond the tool, it is appropriate to use high-speed steel tools, and cool with organic solvents such as carbon tetrachloride. Silicon carbide grinding wheel should be used for grinding, because alumina grinding wheel is easy to crack the grinding surface.
Heat treatment---The main treatment is annealing and solution aging. In order to prevent atmospheric pollution, the heat treatment of tantalum alloy must be carried out in a vacuum of 10-4 torus or in a high purity inert gas, and sometimes even need to wrap the product with tantalum foil.
