Stainless steel is a material with tons to offer. Its popularity also means there are seemingly a million different stainless steel grades. (Actually, there a few hundred.)
As a general rule, stainless deserves consideration if your engineering project requires at least one of these qualities:
- A shiny, beautiful appearance
- Corrosion and oxidation resistance
- Strength at various temperatures
Stainless Steel Grades Chart PDF
Here is a handy chart showing the characteristics and applications of common stainless steel grades. You can also download a color-coded, printer-friendly PDF version here.
SS Grades: What’s It All Mean?
Stainless steel grades are lumped into classes -- the main ones being austenitic, ferritic, and martensitic. The metalworking powers-that-be developed these classes to consolidate chemical and mechanical properties into categories based on the needs of customers’ uses.
1. Austenitic Steels
Austenitic steels mainly reside in the 200 and 300 series. Austenitics are the most specified stainless steel grades thanks to their excellent formability and corrosion resistance.
Austenitic stainless steels contain 15%-30% chromium and 2%-20% nickel for better surface quality, corrosion and wear resistance, and workability. They are nonmagnetic when annealed but -- depending on the nickel content and other composition factors --- can become slightly magnetic when cold worked.
You may notice “L” or “H” attached to some of the grades. “L” denotes low carbon content, which equals increased corrosion resistance. “H” denotes high carbon content, a sign of increased strength.
2. Ferritic Steels
This group of 400-series steels contains 10.5%-20% chromium for corrosion protection and resistance to scaling at high temperatures. Heat treating won’t harden them, and they are always magnetic. Carbon content is low. Ferritic stainless is used in cases where resistance to corrosion is key.
3. Martensitic Steels
These steels, also of the 400 series, usually contain 11.5%-18% chromium and have higher levels of carbon than their ferritic counterparts. Heat treatment of these steels can result in a wide range of useful hardness and strength levels.
Know Your Materials Well
You can see that different stainless steel grades are born to play different roles in metalworking. Make sure your application meshes well with your metal of choice.
Deciding between the two most popular stainless tubing grades, 304 and 316? Check out our guide to their key differences. Need more clarification on what separates 316 and 316L? Keep reading here. Remember, the wrong ingredients can make your project a bad batch from the start.