Understanding the Basics of Hex Cap Screws Grades.

 

Grade 2, Grade 5, and Grade 8 refers to the quality of the steel used and the manufacturing process of the screw. The grade also determines the amount of stress that can be applied.  This metric is referred to as tensile strength. Grade 2 bolts are inexpensive and great for your basic household uses.  Grade 5 hardware uses a higher quality carbon steel and are case hardened to add more strength. A common application for grade 5 hardware is the automotive industry. Grade 8 hardware carries a typical tensile strength of 150,000PSI. Its strength comes from a full heat treatment vs. case hardening like grade 5.  Grade 8 hardware is used in the most demanding situation and environments.  You can identify each grade by the dashes placed on the head of the screw. See below.