The brightness of stainless steel tube after annealing determines the quality of the product. There are also many influencing factors. This paper lists about 5 important factors for reference.
1. Whether the annealing temperature reaches the specified temperature. Stainless steel heat treatment is generally taken solution heat treatment, that is, people commonly called “annealing”, the temperature range of 1040~1120℃(Japanese standard). You can also observe through the annealing furnace observation hole, the stainless steel tube in the annealing area should be incandescent, but there is no softening sagging.
2. Annealing atmosphere. Generally, pure hydrogen is used as an annealing atmosphere. The purity of the atmosphere is better than 99.99%. If another part of the atmosphere is an inert gas, the purity can also be a little lower, but absolutely cannot contain too much oxygen and water vapor.
3, furnace body sealing. Bright annealing furnace should be closed, isolated from the outside air; With hydrogen as a protective gas, only one vent is open (to ignite the exhaust hydrogen). Check the method can be applied with soapy water in the annealing furnace each joint gap, to see whether run gas; One of the most easy to run gas is the place where the annealing furnace into the pipe and out of the pipe, the sealing ring of this place is particularly easy to wear, often check often change.
4. Protect gas pressure. In order to prevent slight leakage, the protective gas in the furnace should be kept at a certain positive pressure. If it is hydrogen protective gas, it is generally required to be above 20kBar.
5. Water vapor in the furnace. On the one hand, check whether the furnace material is dry, the furnace material must be dried for the first time; The second is whether the stainless steel pipe into the furnace remains too much water stains, especially if there is a hole above the pipe, do not leak into it, otherwise it will destroy the furnace atmosphere.
Pay attention to basically these, normal, after the furnace should be back about 20 meters of stainless steel pipe will start to shine, bright reflective kind.
