Manufacturing engineers looking for stainless steel products want to know what type of stainless resists corrosion at different temperatures.
Stainless steel is not technically unable to stain or rust. Under low oxygen or high salinity (saltwater), it’s susceptible to corrosion. Various grades of stainless react differently, based on their chemical composition – how much carbon, chromium or nickel they contain. The chromium in stainless steel forms a film that blocks oxygen from corroding the steel surface. The result is “passivation,” which means the material is passive, not so active, when confronted by substances like air and water.
Temperature, fluids and stress on the structure can all spur corrosion. According to the McNally Institute website, the rate of corrosion attack doubles with every 18 F (10°C) rise in temperature. That can be caused by friction between parts as well.
The following table from ASM (American Society for Metals) shows the approximate maximum service temperatures at which various grades of stainless resist oxidation in dry air. The temperatures depend on the actual environmental conditions; in some instances, even lower temperatures will result in oxide scaling.
|GRADE||INTERMITTENT (°C)||CONTINUOUS (°C)|
Table Credit: ASM Metals Handbook