Grades of Stainless Steel

Unlike carbon steel fasteners, stainless steel bolts are often called out by the grade of the raw material rather than a specific ASTM specification. Three of the most common are 18-8, 304, and 316.

• 18-8 Stainless Steel – The term 18-8 refers to the 18% chromium and 8% nickel alloy composition of the steel. It generally refers to any bolt, nut, or washer made from 300 series stainless steel.  It could be called a “commercial” grade of stainless, in that many common, mass-imported items are sold as 18-8.
• 304 & 316 Stainless Steel – These are the most common grades of stainless steel roundbar found in the marketplace. The properties of these two grades are similar, however Type 316 has a lower chromium content, a higher nickel content and a 2% molybdenum is added, which make 316 more corrosive resistant than 304.