Introduction to Corrosion Resistance of Stainless Steel

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  • Publish Time:2022-11-10
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Although it is easier for stainless steel plates to remove surface stains and other forms of iron, just like standard steel, stainless steel plates will eventually rust or discolor naturally through fingerprints and grease markings. The difference is, stainless steel will not corrode or rust as easily due to what it's made of. 

All steel has the same basic iron and carbon composition, but stainless steel plates also contain the right amount of the compound element chromium, giving stainless steel its excellent corrosion resistance performance. This is where things get complicated. Stainless steel plate has many grades with different alloy composition, so their physical characteristics are also different. Stainless steel plates must contain at least 10.5% chromium. According to the grade, some stainless steel plates may also contain higher chromium content, as well as other alloys such as molybdenum, nickel, titanium, aluminum, copper, nitrogen, phosphorus, and selenium.

The two most common stainless steel plates are 304 and 316 and the key difference is the addition of molybdenum. Molybdenum is an alloy that can significantly enhance corrosion resistance, especially in environments with more brine or chloride exposure. 316 stainless steel contains molybdenum, while 304 stainless steel does not. So for outdoor products like rails and bollards, 304 stainless steel plate is the most economical and practical choice for most applications. Although it does not have the chloride resistance of 316, the price of 316 stainless steel plate is slightly higher, which is worth a lot in areas with high chloride exposure, especially coastal and severely saline roads.

Corrosion is a natural phenomenon. Pure elements always react with their surroundings, which is why very few elements are found naturally in their pure form, and iron is no exception. Under wet or humid conditions, iron reacts with oxygen contained in water to form iron oxide, also known as rust. Red sheet oxides tend to deteriorate, leaving more material exposed and corroded. Iron and standard carbon steel are sensitive to this type of corrosion. Stainless steel plates have the inherent property of forming a passivation layer to protect against!