A bolt's property class designation consists of two numerical parts, which represent the nominal tensile strength and the yield-to-tensile strength ratio of the bolt material, respectively. For example, a bolt with a property class of 4.6 signifies the following:
The nominal tensile strength of the bolt material is 400 MPa;
The yield-to-tensile strength ratio of the bolt material is 0.6;
The nominal yield strength of the bolt material is 400 × 0.6 = 240 MPa.
For a high-strength bolt with a property class of 10.9-after its material has undergone heat treatment-the following properties are achieved:
The nominal tensile strength of the bolt material is 1000 MPa;
The yield-to-tensile strength ratio of the bolt material is 0.9;
The nominal yield strength of the bolt material is 1000 × 0.9 = 900 MPa.
