Annealed Stainless Steel Tubing

What is annealed tubing?

Annealed tubing has been heat-treated to remove internal stresses and increase ductility. In short, the annealing process softens the tube relative to cold worked (or “hard tempered”) tubing.

300 series stainless steel anneals at a temperature of 1900 degrees Fahrenheit minimum. Tubing can be annealed several ways by Vita: in coil form through a strand annealing furnace, a belt furnace or an enclosed oven with a door. To maintain a bright finish on the tube surface, an atmosphere free of oxygen and a low dew point must be used. Alloys other than the common 300 series (304, 316, 321) can be annealed as well, but at different temperatures and durations of heat treatment in the furnace. After treating in the furnace, the last step in the annealing process is quenching---a process to rapidly cool the tube and complete the transformation to an annealed state.

Certain tubing alloys, such as 17-7, can also be hardened with temperature treatment because of the chemical makeup of these alloys, however such processing is generally referred to as “heat treatment” when the properties of the tube become harder.

Tubing in annealed conditions can be further cold worked to increase temper and tensile strength. Some applications benefit from the use of annealed tubing, such as bent parts with tight radii or parts that require steep swaged reductions or forming processes that could result in cracking if performed on a hard temper tube. Annealed tubing can be supplied in straight random lengths or coil form as well, however maintaining straightness on long lengths of annealed tubing can be a concern if the wall is thin due to the potential damage from handling or rough transport during shipping.

 

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