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Small Diameter 321 Stainless Steel Tube

321 stainless steel tubing (EN 1.4541, UNS S32100) has particular characteristics that make it useful for high temperature applications up to approximately 900ºC (or intermittent heating applications approaching 900ºC max) and aggressive, caustic environments. Similar in performance features to 347 Stainless steel, 321 utilizes an additional element (titanium). Small in percentage by weight, titanium in combination with other common 300 series elements like chromium and nickel form an alloy that handles high temperatures and corrosive environments more readily than lower numbered alloys in the 300 series.

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321 Small Diameter Stainless Steel Tubing

Titanium’s affinity for free carbon atoms relative to chromium in the alloy prevent the formation of chromium carbide precipitation at the boundary layers of the HAZ (heat affected zone) where welding occurs. Titanium carbide, the compound tying up significant portions of carbon present in the alloy, also scatters widely throughout instead of grouping at the grain boundaries (like chromium carbide) where it can be attacked by acids and create a starting point for broad product corrosion.

Titanium’s preference for bonding with carbon prevents those carbon atoms from bonding with chromium, keeping the chromium atoms free to bond with oxygen at the surface of the tube. This feature---keeping chromium unbound---allows the natural formation of the chromium oxide boundary layer only atoms deep at the tube surface. Chromium oxide’s presence is the key attribute that allows all stainless steels to offer greatly improved corrosion resistance and bright, unblemished surfaces relative to conventional, non-stainless steel tubes.

As application temperatures and concentrations of caustic solutions increase, 321 stainless steel tubing’s improved resistance to intergranular corrosion shines relative to lower numbered alloys in the 300 series whose resistance to corrosion in these more extreme environments is not as strong.

Industries & Applications:

Useful in a variety of demanding applications such as aerospace, chemical processing, oil and gas, food processing and high temperature metallic o-ring seals, Vita Needle manufactures 321 stainless steel tube products from 5/16” OD and smaller, and quantities 10 to 100,000’ or more. It is sold in coil, straight lengths, or fabricated parts. 321 is readily fabricated with all of Vita Needle’s reductive/conventional machining capabilities including electrochemical and EDM. It can be cold worked to high tensile strengths over 160 KSI, depending on the OD and tube wall. 321 is also offered by Vita Needle in annealed temper for applications requiring softer tubing. Because we can weld, draw and fabricate in house, our lead times and pricing routinely beat competitor offerings in this space. Please send us your inquiry or questions and we look forward to responding promptly!

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