Stainless steel can be found in a number of different types, each with unique properties and compositions. In the 1930s and 1940s, a standardized numbering system was developed by the AISI (American Iron and Steel Institute) for the different types of stainless steel, e.g. Type 301 stainless steel. The AISI also published a Stainless Steel products manual that listed these designations and the chemical analysis as well as most mechanical and physical properties of each individual grade. They are not specifications as such, just definitions of the individual grades, with most specifications being provided by the ASTM (American Society for Testing Material).

Stainless steel types are designated with three digits (200 series, 300 series, 400 series, etc.). Common stainless steel series and types Rolled Metal Products supplies are as follows:

200 Series – general purpose austenitic chromium-nickel-manganese alloys

  • Type 201 – hardenable through cold working

300 Series – austenitic chromium-nickel alloys providing high corrosion resistance and strength

  • Type 301 – highly ductile for formed products.
  • Type 302 – additional carbon for higher strength
  • Type 304 / 304L – the most common grade
  • Type 305 – same as 304 but contains more nickel to decrease work hardening
  • Type 309 – better temperature resistance than 304
  • Type 310 / 310S – highly alloyed used for high-temperature applications
  • Type 316 / 316L – second most common grade, typically used for food and surgical applications
  • Type 321 – similar to 304 but lower risk of weld decay due to added titanium
  • Type 347 – similar to 304 but stabilized with columbium to resist intergranular corrosion

400 Series – ferritic and martensitic chromium alloys providing high strength and wear resistance

  • Type 409 / 409 UF – lowest cost for high temperature and corrosion resistance
  • Type 410 – wear-resistant, but less corrosion resistant
  • Type 430 – good formability and commonly used for decorative applications
  • Type 436 – provides excellent resistance to stress corrosion cracking in the presence of chlorides
  • Type 439 – higher grade version of 409, commonly found in automotive catalytic converters
  • Type 440A – least amount of carbon, most stain resistant
  • Type 441 – provides good oxidation and corrosion resistance

What stainless steel type do you require?

Choosing the right stainless steel grade for your applications can be a crucial decision depending on your specific requirements. Our experts are available to assist you with any stainless steel questions you may have. Send us the qualities and specifications you need for fabrication and production, and we can ensure that you will receive the right stainless steel types for your needs.