How To Understand Markings on Stainless Steel Nuts & Bolts

Stainless steel nuts and bolts have markings on them to help the user identify their properties. We have put together a quick guide below on how to decipher the code.

The three marks you will most commonly find are as follows;

• the name of the manufacturer (or an abbreviated version)
• The grade of stainless steel, i.e. A2 or A4. You can read more about this here.
• The tensile strength - the measure of a metals resistance to breaking apart in two pieces.

Example 1

Using the example of the nut below, THE is the manufacturer, A2 is the grade of stainless steel and 70 is the tensile strength. A2-70 is the most common standard version of A2 type stainless but you’ll also see A2-50 and A2-80 denoting higher and lower strength versions.

STAINLESS STEEL NUT MARKINGS

Example 2

In the second example below of a hexagon setscrew, ABP is the manufacturer, A4 is the grade of stainless steel and 70 is the tensile strength. A4-70 is the most common standard version of A4 type stainless but there is also A4-50 and A4-80 for different higher and lower strength versions.

STAINLESS STEEL BOLT MARKINGS