Views: 0 Author: Site Editor Publish Time: 2022-08-08 Origin: Site
Tantalum cannot be processed by the common method of processing ordinary metals. Generally, the initial process is forging, processing and heat treatment, and flat or round medium and small-sized blanks are made by hammering and stamping.
Tantalum cannot be processed by the common method of processing ordinary metals. Generally, the initial process is forging heat treatment,
The plate blank or round medium and small-sized blank is made by hammering and stamping. Unlike ordinary metals, tantalum cannot be hot worked. The recrystallization temperature of tantalum is more than 1000 ~ C. if heated, even if a general protective coating is made, excessive oxidation will occur. What is more serious is that if tantalum is exposed to such a high temperature, not only excessive oxidation will occur on the surface of tantalum, but also oxygen can invade between atoms in the matrix, making tantalum brittle. Not only oxygen but also nitrogen, carbon and hydrogen can make tantalum brittle. For the above reasons, tantalum is generally not thermally processed. When it is necessary to carry out thermal processing, a protective coating shall be made or it shall be carried out in an inert gas atmosphere.
Since the reaction between tantalum and oxygen is active, it is necessary to avoid conducting it in an atmosphere even in the presence of a little air
Heat treatment. Therefore, almost all annealing is carried out in a high vacuum, and the airtightness of the heating furnace must be very high. Generally, the heat treatment temperature of tantalum is generally 950 ~ 1300 ℃, and tantalum and commonly used Tantalum Alloys do not undergo phase transformation within this temperature range. The heat treatment is only used for annealing, so the heating temperature and cooling speed are not important. In order to produce complete recrystallization, the heat treatment time should be slightly longer.
Commercial tantalum has a high purity. The grain size becomes very large by annealing. The size of crystal particles is determined by cold processing, purity, temperature and process steps. Therefore, temperature control and process control are important means to determine the crystal size.
Tantalum, unlike many other metals, must be very clean before heat treatment. If it is not cleaned thoroughly, surface pollution caused by hydrogen, oxygen, nitrogen and carbon will occur and become embrittlement (hardening) structure. Because hydrogen, oxygen, nitrogen and carbon are very active and intrusive elements within the temperature range of tantalum annealing, once they are contaminated by these elements, there is no way to remove them except remelting.
Almost all tantalum plates are cold processed. Generally, starting from 15-30cm tantalum ingot, cold forging results in a slab of about 8-10m thick, and then cold rolling is started from this slab, with a compression rate of more than 95%. In commercial production, the slab is usually rolled into 0.63-1.2cm thick plate with a width of 51-102cm by two or four rolling mills. Typical rolling is performed at or near room temperature to prevent oxide formation on the surface. When hot rolling is required, due to recrystallization, the temperature rises to 1000 ℃, and intense oxidation reaction occurs.
Almost all thick plates are annealed by heat treatment in vacuum. Since there is no phase distortion, the speed of heating and cooling is not important. Further rolling is carried out with ordinary rolling mills, and at this time, 4 rolling mills and multi rolling mills are generally used. Since tantalum is very soft, attention should be paid to prevent scratches during processing and transportation.
In order to manufacture rod products, first, forging or extruding to moderate size in the middle, with a representative section yield of 70% - 90%, and then the material is subjected to annealing heat treatment. For further processing, forging, rolling, extrusion or drawing processes are usually used. The wire is processed with a common wire drawing machine. Because tantalum material is very soft, it is easy to produce scratches, and the surface problem is very large during drawing. The manufacturer should pay special attention to the surface condition and lubrication
Tantalum can be used to produce welded pipes and seamless pipes and has a wide range of applications. Seamless pipes are manufactured by extrusion, pipe reduction or deep drawing with plates. The manufacturing method of welding is to form a strip, then make a tube, and then weld the seam with gas tungsten arc (GTAW).
Name: tantalum tube (seamless tube)
Brands: TA1, TA2, taw2.5, taw7.5, taw10, tanb3, tanb20, tanb40, etc;
Standard: GB / t8182-2008; Or according to the enterprise standard of Beijing Dongfang Zhongke tantalum niobium
Purity: purity of pure tantalum is more than 99.95%;
State: annealed state (m) or hard state (y);
Advantages of welded pipe:
1: Uniform wall thickness and good internal surface quality
2: High production efficiency. Low cost
3: Easy to produce large diameter pipes
4: Short production cycle
5: Product quality is easy to control
Disadvantages of welded pipe:
1: Poor flexibility, not suitable for producing products with large specifications and small batches
2: Welds are often weak links
3: Weld cleaning is difficult
4: Ovality is not easy to control
5: High dimensional accuracy is required for the strip used
Therefore, welded pipes are generally suitable for producing large-scale products.
Advantages of seamless pipe:
1: It can produce small size pipes and capillary pipes
2: Good flexibility, suitable for producing products with small batch and large specifications.
3: All parts of the pipe have uniform performance
Disadvantages of seamless pipe:
1: The uniformity of wall thickness is difficult to control
2: Long production cycle and low yield
3: Complex equipment and large investment
4: Difficult to produce large diameter pipes
Therefore, seamless pipes are generally suitable for the production of products with small batches and large specifications.
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