Knowing the facts about stainless steel grades, types, and properties will help in purchasing the right product for the right location.
The element that reduces corrosion and responsible for making stainless steel "stainless" is chromium. At least 10.5% of chromium (Cr) is present in all stainless steel. Other elements like nickel, manganese, and molybdenum are added to create different types of stainless steel.
Each element has unique advantages when added to stainless steel:
- Chromium (Cr) offers corrosion resistance
- Nickel (Ni) is easier to form
- Manganese (Mn) is a nickel substitute
- Molybdenum (Mo) offers additional corrosion resistance
Stainless Steel Grades:
200 series - Austenitic
These stainless steels contain between 15 - 30% Cr and 2 - 20% Ni. Bradley commonly uses the 201 grade. Some typical applications for 200 series stainless steel include showers, truck trailer frames, hose clamps, cookware, sinks, appliances, automotive trim, and architectural applications.
Alloy compositions of common 200 Series Grades
- 201: Cr 16 - 18%, Ni 3.5 - 5.5%, Mn 5.5 - 7.5%
300 series - Austenitic
This series of stainless contain the same range of chromium and nickel as the 200 series. Some commonly used grades are 301, 304, and 316. All of 300 series stainless steel are typically used for chemical equipment, food equipment, security fixtures, showers, and other architectural applications. 316 is used where severe corrosion exists; marine environments and chemical plants.
Alloy compositions of common 300 Series Grades
- 301: Cr 16 - 18%, Ni 6 - 8% , Mn 2%
- 304: Cr 18 - 20%, Ni 8 - 10.5%, Mn 2% .
- 316: Cr 16 - 18%, Ni 10 - 14%, Mn 2%, Mo 2 - 3%
400 series - Ferritic
These metals contain between 10.5 - 20% chromium. Unlike the 200 and 300 series, 400 series are magnetic. Some typical applications include interior use, fasteners, cooking utensils, appliance trim, sinks, automotive emission control exhaust systems.
Alloy compositions of common 400 Series Grades
- 430: Cr 16 - 18%, N i0.75%, Mn 1%
Additional sources: Specialty Steel Industry of North America