Welds process volume

If the underground chemist has to make his own one-gallon reaction bottle, he uses stainless steel 1/8 to 3/16 inch thick, such as a section of stainless steel pipe. For a volume of about one gallon, it should be about 16 cm in diameter and 20 cm in height. The bottom is Tig welded on, this process being much easier if it starts out a few millimeters larger in diameter than the pipe section. 

Both tantalum and niobium are available in foil, sheet, and deep-drawn tubing prepared from both welded and seamless stock. Tubing with a wall thickness of from 10-30 mil (0.25-0.76 mm) is most useful. Seamless tantalum tubing sells in quantity for about 75/m in 6-9-m diameter sizes, whereas an equal amount (volume) of niobium tubing costs only about 20% as much. The materials now available have been electron-beam melted under vacuum, a process which gives a substantial decrease in impurities through volatilization of most of the O, N, H, and C (as CO). Principal impurities in Ta are thus the heavy metals (e.g., 0.01-0.05% each of Wand Nb), and guaranteed purities are >99.85% total. Niobium runs 99.7-99.8% total and contains principally small amounts of W and Ta. 

Weld nugget The fully recrystallized area, sometimes called the stir zone, refers to the zone previously occupied by the tool pin. The term stir zone is commonly used in friction stir processing, where large volumes of material are processed. 

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