Tantalum tube manufacturing process flow

Blooming

Tantalum cannot be processed using ordinary methods of processing general metals. The general starting process is forging, processing, and heat treatment,

Produce flat billets or circular small and medium-sized billets using two methods: hammering and stamping. Unlike ordinary metals, tantalum cannot be hot working. The recrystallization temperature of tantalum exceeds 1000~C. If heated, even with a general protective layer, excessive oxidation will occur. More seriously, if tantalum is exposed to such high temperatures, not only does excessive oxidation occur on the surface of tantalum, but oxygen can also invade between atoms inside the matrix, making tantalum brittle. Not only oxygen, but also nitrogen, carbon, and hydrogen can make tantalum brittle. For the above reasons, hot working of tantalum is generally not carried out. When it is necessary to carry out hot working, protective coating or inert gas atmosphere shall be applied.

heat treatment

Due to the active reaction between tantalum and oxygen, it is necessary to avoid conducting it in an atmosphere even with a small amount of air

Heat treatment. Therefore, almost all annealing is carried out in a high vacuum, and the airtightness of the heating furnace must also be high. Usually, the heat treatment temperature of tantalum is between 950~1300 ℃, and tantalum and commonly used tantalum alloys do not undergo phase transformation within this temperature range. Heat treatment is only used for annealing, so the heating temperature and cooling rate are not important. In order to produce complete recrystallization, a slightly longer heat treatment time is better.

Commercially produced tantalum has a high purity. By annealing, the grains become very large. The size of crystalline particles is determined by cold processing, purity, temperature, and process steps. Therefore, temperature control and process control are important means to determine the size of crystallization.

Tantalum, unlike many other metals, must be very clean before heat treatment. If not cleaned very clean, surface contamination caused by hydrogen, oxygen, nitrogen, and carbon can occur, forming brittle (hardened) structures. Because hydrogen, oxygen, nitrogen, and carbon are very active intrusive elements within the temperature range of tantalum annealing, once contaminated by these elements, there is no way to remove them except by remelting.