304 stainless steel plate chromium has a high chemical stability, can form a passivation film on the steel surface, so that the metal is isolated from the outside world, protect the steel plate from oxidation, increase the corrosion resistance of the steel plate.
After the passivation film is destroyed, the corrosion resistance decreases.
If the surface of the stainless steel plate oxide skin thickness is not uniform, thick place and thin place below the substrate metal surface finish is also different, surface and pickling when the surface oxidation skin dissolution and oxidation skin adhesion site of the substrate metal by acid erosion degree is different, so, the surface of the steel plate is not uniform. Therefore, when heat treatment is heated, it must be made to form an oxidized skin evenly.
Stainless steel Plate If the surface of the workpiece is attached with oil, the thickness of the oxide skin at the attachment of the oil and the thickness and composition of the oxide skin of the other parts are different, and carburizing will be produced.
The carburizing part of the oxide subcutaneous matrix metal will be seriously eroded by acid.
The surface of the workpiece, such as lubricating oil attached to cold processing, must be fully skimmed in trichloroethylene skimming agent, caustic soda solution and then washed with warm water, and then heat treatment.
Stainless steel Plate If there is debris on the surface, especially organic matter or ash attached to the workpiece, heating will of course have an effect on the oxidized skin.
【Differences in atmosphere in the Furnace】
The difference of atmosphere in stainless steel plate furnace The atmosphere in the furnace varies from part to part, and the formation of oxidized skin will also change, which is also the cause of uneven after pickling. Therefore, when heating, the atmosphere in each part of the furnace must be the same. To that end, the cycle of atmosphere must also be taken into account.
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