The stainless steel roller is made of stainless steel. A certain amount of chromium added to the stainless steel can prevent the surface of the stainless steel roller from being further oxidized and corroded. Stainless steel rollers have excellent corrosion resistance, wear resistance, high temperature resistance and other properties, and are suitable for industries that have to work in harsh conditions for a long time. So does the stainless steel roller really not rust as its name suggests?
In fact, stainless steel rollers are not immune to rust, and may rust under certain circumstances.
The reasons for rust on the surface of stainless steel rollers may be as follows:
The chromium oxide film is damaged: Chromium is added to stainless steel. The chromium oxide film formed by it can prevent the stainless steel roller from being oxidized and corroded. If the chromium oxide film on the surface of the stainless steel roller is damaged (such as scratches, cuts, etc.), it will lose its protective effect, resulting in rust on the surface of the stainless steel roller.
Long-term exposure to harsh environments such as strong acid and strong alkali: Although the rollers made of stainless steel are corrosion-resistant, if they are immersed in harsh environments such as strong acid and strong alkali for a long time, the stainless steel will also rust. The chromium oxide film lacks additive enhancement: Some stainless steel materials made of stainless steel rollers need to add a certain amount of additives to enhance the stability and corrosion resistance of the chromium oxide film. If the content of these additives is insufficient or missing, the corrosion resistance of the stainless steel roller will decrease, causing rust.
Erosion by chloride ions and other pollutants: In some specific environments, such as corrosive environments such as the ocean, chloride ions and other pollutants can easily corrode the chromium oxide film on the surface of the stainless steel roller, causing rust.
Therefore, stainless steel rollers may also rust, but they are less prone to rust than other carbon steel materials. The corrosion resistance of commonly used stainless steel materials from large to small is roughly 904L > 2205 duplex stainless steel > 316L > 304L, so it is very important to choose the appropriate stainless steel specifications according to different scenarios.
The following are the characteristics of commonly used stainless steel for reference:
1. 304 L: Low carbon, so it is more corrosion-resistant and easy to heat treat, but has poor mechanical properties. It is suitable for welding and products that are not easy to heat treat.
2. 309S: Contains a large amount of chromium and nickel, so it has good heat resistance and oxidation resistance. It is used in heat exchangers, boiler components, and jet engines.
3. 316: It has better resistance to chloride corrosion. The addition of molybdenum element gives it a special corrosion-resistant structure. Compared with 304, it has better resistance to chloride corrosion and is also used as "marine steel". Mainly used in the food industry, watches and clocks, pharmaceutical industry and surgical equipment.
4. 316L: Low carbon, so it is more corrosion-resistant and easy to heat treat. It is used in chemical processing equipment, nuclear power generators, and refrigerant storage tanks.
5. 440: High-strength cutting tool steel with slightly higher carbon content. After appropriate heat treatment, it can obtain higher yield strength and its hardness can reach 58HRC, which is among the hardest stainless steels. A common application example is "razor blades".
6. 2205 duplex stainless steel is a nitrogen-added duplex stainless steel. It has high strength, good impact toughness and good overall and local stress corrosion resistance. The main feature of 2205 duplex stainless steel is that the yield strength can reach 400-550MPa, which is twice that of ordinary austenitic stainless steel. This feature allows designers to reduce weight when designing products, so they can save materials. This alloy is stronger than 316 and 317L It also has a price advantage and reduces equipment manufacturing costs. In terms of corrosion resistance, especially in harsh medium environments (such as seawater, high chloride ion content), the resistance to pitting corrosion, crevice corrosion, stress corrosion and corrosion fatigue of duplex stainless steel is significantly better than that of ordinary austenite. Stainless steel, comparable to high-alloy austenitic stainless steel.
7. 904L stainless steel is a high-alloy stainless steel with extremely strong corrosion resistance, including acid resistance, alkali resistance, seawater corrosion resistance, etc. Its corrosion resistance is even comparable to that of titanium alloys. 904L stainless steel is often used in industrial equipment in strong acid and alkali environments such as sulfuric acid, phosphoric acid, and chloride, as well as equipment in marine environments. 904L stainless steel also has extremely high wear resistance, good processability and weldability.
May 11, 2024
