The oxide film on stainless steel plate is actually a five color transparent film. Its color change is influenced by the interference principle of light. What color does it appear in the light interference, mainly caused by the thickness change of oxide film on the stainless steel plate surface. Therefore, the oxidation resistance of the stainless steel plate is the most effective method to solve the high temperature discoloration of the stainless steel.
The factors that affect the oxidation resistance of stainless steel are mainly chemical elements, the influence of oxide film and the influence of surface roughness.
The first is the chemical elements, carbon content in stainless steel is low in the high temperature environment of carbon atoms in the oxidation process is easy to spread to the inside organization of stainless steel substrate, so the oxidation process of stainless steel plate with carburizing process, test chromium, silicon and nickel content of different types of stainless steel high-temperature cycle test. After the test, the ratio of carbon content in the stainless steel is measured, and the degree of oxidation of the stainless steel is determined by the carburizing amount.
In order to further verify the effect of silicon on the carburizing resistance of stainless steel, the proportion of silicon element in 310S stainless steel should be adjusted, followed by high-temperature cycling test. The final test results show that the high temperature oxidation resistance of stainless steel plate has been significantly improved when the mass fraction of chromium is increased to 22% or the mass fraction of silicon is more than 2%.
The effect of the oxide film on the oxidation resistance of the stainless steel plate is also seen. The tough oxide film on the stainless steel plate can prevent the oxidant from invading the stainless steel, that is to prevent the oxidation from continuing to produce, while the loose oxide film will make the oxide film continue to thicken. In continuous production line, a continuous acid washing method is used to make forced oxidation of the stainless steel plate to enhance the density of the oxide film on the stainless steel plate.
The last is the influence of the surface roughness of the stainless steel plate, and the oxidation of the surface of the stainless steel plate will be thickened by the oxidation of the surface in the high temperature environment. There is a direct link between the material and its oxidation resistance and heat absorption capacity of stainless steel material, surface roughness, surface color of stainless steel plate will affect the heat absorption unit area and the influence degree of discoloration of stainless steel.
The practice shows that when the surface roughness of BA stainless steel plate is below 0.022 m, the endothermic capability of stainless steel decreases obviously, and the stainless steel will not oxidize further. The thickness of oxide film is basically unchanged under high temperature, and the degree of discoloration is also very slight.
Source: China Stainless Steel Plate Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)