Stainless Steel Pipe Fittings

Surface quality inspection of 304 stainless steel plate

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The surface quality of 304 stainless steel plate, usually the main heat treatment after pickling process, if the heat treatment before a surface oxidation process to generate thick skin, or uneven microstructure, surface roughness and uniformity that cannot improve the use of pickling stainless steel plate. Therefore, attention should be paid to heat treatment and prior surface cleaning.

If uneven surface oxide thickness of stainless steel plate, metal surface finish thick and thin places of the following is not the same degree, dissolution and oxidation skin and pickling board surface oxide skin attachment site of base metal was also different, so the degree of corrosion, stainless steel surface is not uniform. Therefore, in the heating of stainless steel plate heating, it is necessary to make it evenly oxidized skin. And to meet this requirement, we must pay attention to the following problems.

Once the stainless steel plate is heated, there is oil on the surface of the workpiece, and the thickness and composition of the oxide scale and other parts of the oxide in the oil attachment area are different, and the part will also be carburized. The carburized parts of the oxidized stainless steel matrix are strongly eroded. The oil droplets ejected from the heavy oil burner at the initial combustion will also be greatly affected if it is attached to the stainless steel plate. The fingerprint of the operator is also attached to the stainless steel plate. Therefore, the operator is best not to touch the stainless steel directly with his hands, even if you want to touch, you should bring clean gloves and then operate.

304 stainless steel plate surface of the workpiece if attached when processing cold lubricating oil, it must use warm water to clean the trichloroethylene degreasing agent, caustic soda solution fully after degreasing, followed by heat treatment.

Stainless steel plate, if the surface is still debris, especially organic or gray in the stainless steel plate surface, heating will certainly affect the oxide skin. Stainless steel plate furnace atmosphere will lead to different parts of the difference, the formation of oxide skin will also produce change, and this is also lead to stainless steel plate after acid uneven cause of formation. Therefore, when heating the stainless steel plate, the atmosphere in each part of the furnace must be the same. In order to solve this problem, we should also consider the cycle of good atmosphere.

In addition, the formation of heating bench used brick, asbestos, if there are water, so when heated, water will evaporate, direct contact with the water vapor of the stainless steel plate part and other parts of the atmosphere will be different, the oxide coating is also different. Therefore, the direct contact with the heating stainless steel plate workpiece must be completely dried before use. However, after drying, such as placed at room temperature, moisture in high condition, the water will still condense on the surface of the workpiece. Therefore, it is better to dry before use.

304 stainless steel plate if the oxide skin remnants of the local heat treatment before, there will be residual oxide parts and parts without oxide after heating, the difference of composition and thickness of oxide is formed on the skin, resulting in pickling stainless steel plate surface is not uniform, so should pay attention not only to the final heat treatment, but also pay attention to intermediate heat treatment and pickling.

Source: China Plate Manufacturer – Yaang Pipe Industry Co., Limited (

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Stainless Steel

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