Tubes and round rods of refractory metals
Tubes and round rods of molybdenum and its alloys are widely used as covers of the thermocouples measuring the temperature in the range 1200-1800ËšC, as cathode in vacuum microwave equipment and instruments, as part of the combustion chambers in the rocket engines, gas discharge tubes and covers of the fuel elements in NPS using the thermal neutrons.
The application area of molybdenum alloys is stipulated by its high-temperature strength, high coefficients of elasticity, strength-to-weight ratio, melting temperature, erosive resistance as well as thermal shock insensitivity.
Tubes and round rods of niobium (columbium) have higher ductility, good weldability and oxide fixity in comparison with other refractory metals. The application area of tubes and round rods of niobium and its alloys is similar to molybdenum application, but the operating temperature range is lower and amounts to 1000-1400˚С; the operation at negative temperatures up to -196˚С is also possible.
Tubes and round rods of tungsten and its alloys are used in the combustion chambers of rocket engines and as other parts in the rocket engineering, operating at temperatures of 2500-2700ËšC. This material is also used in the nuclear industry, mainly in the sublimation process of uranium.
Tubes and round rods of tantalum and its alloys have high corrosion resistance and maintain the ductility at temperatures up to -196ËšC. However, tantalum, more than any other refractory metals, prone to rapid oxidation and dissolves gases intensively at increased temperatures.
Alloys of tantalum are recommended for operation in a wide range of temperatures - from -130ËšC to 2900ËšC. The application area is mainly connected with the enrichment of the precious metals.
The production technology of tubes and round rods of refractory metals and its alloys, operating at DSTP LLC, is a combination of the following operations:
- warm (cold) deformation by pilgrim rolling (pilgering), mandrel bar drawing, sink drawing, as well as warm deformation at the radial forging machine (for round rods);
- chemical treatment;
- vacuum heat treatment with the depth of vacuum 10â»â´ millimeters of mercury;
- finishing;
- quality inspection.