Can Stainless Steel Kitchens Rust?
Stainless steel is a popular material for use in kitchens, both in kitchen fittings and appliances. While stainless steel is more corrosion resistant than most steels, under some circumstances it can form rust.
Here is a guide to the likelihood of your stainless steel rusting.
Stainless steel is not a single type of steel but range of steels, which have different properties due to their different chemical compositions. The numerical codes indicate the steels composition with the 300 series have 0.15% carbon, at least 16% chromium and a balance of nickel or molybdenum to achieve the necessary crystalline structure for strength. 400 series steels have an ultra low carbon level of less than 0.05% and between 12-13% chromium. The duplex series have high levels of chromium of above 20% giving them a great corrosion resistance for a lower price than surgical steels.
In kitchens the trade off tends to be between strength, cost and corrosion resistance. The more expensive but strong steels include 420 (martensitic), which is often used in tools and knives. Cheaper grades of steel include 430, 304 and 306, which have a lower corrosion resistance and are often used in home kitchen bench tops and to act as a decorative surface on cupboards, appliances or doors. The duplex series includes 904L and are ideal for applications that will hold hot, acidic or salty fluids.
Steels are more likely to rust if exposed to acid or salt spray. This means that if you have an outside kitchen in a coastal area, you will need a higher grade of stainless steel to prevent rust than if you have stainless steel in a mainly decorative usage in an indoor kitchen. Equally, if you commonly pickle or preserve foods, you will also need kitchen fitting made from a higher grade of stainless steels.
The different steel grades will gain strength from different heat exposures. 300 series are often cold-worked to give strength and are exposed to high temperatures will be more corrosion resistant, as the crystalline structure is lost. Martensitic structures can be strengthened by heat exposures and do not lose corrosion resistance unless heated then dramatically cooled. Duplex structures are relatively immune to heat effects in the normal range of kitchen operations.
Surfaces that have already been roughened are more likely to corrode than a smooth finish. There is a great deal of variation in the description of “brushed” or matte finishes, and, as a result, the exact effect of surface finish can be hard to measure in domestic applications.
For more information, contact a company such as Ackland Stainless Steel.