304 stainless steel capillary is a kind of precision pipe fittings that are very particular about the process. Among them, the "annealing" process is one of the very important processes, which can make this stainless steel precision pipe fittings have stronger corrosion resistance and eliminate work hardening. Today I will show you what special conditions are needed in the "annealing" process.
Necessary conditions for "annealing":
1. Whether annealing can achieve the required temperature: The stainless steel heat treatment process generally adopts the solution heat treatment process, or "annealing", and the temperature range of this process is 1040~1120℃ (Japanese standard). stainless steel capillarys can also be viewed in the inspection hole of the annealing furnace during production and processing. The stainless steel capillarys in the annealing zone should be incandescent without softening and sagging.
2. Annealing atmosphere: Generally, pure hydrogen is used as the annealing atmosphere for 304 stainless steel capillary tubes. The purity of the atmosphere is preferably above 99.99%. If there is another inert gas in the atmosphere, the purity of pure hydrogen can be moderately reduced. But it is strictly prohibited to carry too much oxygen and water vapor.
3. Furnace body tightness: The bright annealing furnace must be sealed and isolated from the outside air. Generally, hydrogen is used as the protective gas. The furnace body has only one air outlet to open, which is convenient for igniting hydrogen. And the way of inspection is to wipe water on each joint gap of the annealing furnace, and carefully observe whether there is any air leakage. The most likely location for air leakage is the place where the annealing furnace enters and exits the pipe. The sealing ring here is easy to wear, so it needs to be checked and replaced frequently.
1. Always maintain the gas pressure: To prevent gas leakage, the maintenance gas in the bright furnace should always maintain the corresponding positive pressure. If the maintenance gas is hydrogen, most of it must be above 20kBar.
2. Keep the furnace in a dry state: First, check whether the furnace body is dry or not. When starting the initial furnace installation, the furnace body material must be dried; then check whether the 304 stainless steel capillary tube entering the furnace has residual water stains, because some stainless steel capillarys may have holes. If water is brought into the bright furnace, it will adversely affect the stainless steel processing process.
Every process can affect the quality of stainless steel capillary fittings. Only when the details are made to the extreme, can high-quality 304 stainless steel capillaries be produced. The above is a summary of the relevant knowledge about the "annealing" process of precision stainless steel capillary fittings.