According to relevant standards, the performance grades for carbon steel and alloy steel bolts are classified into over ten categories, including 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, and 12.9. Among these, bolts of Grade 8.8 and higher are manufactured from low-carbon alloy steel or medium-carbon steel and undergo heat treatment (quenching and tempering); these are commonly referred to as high-strength bolts. The remaining grades are commonly referred to as ordinary bolts.
The designation for a bolt's performance grade consists of two numerical parts, which represent the nominal tensile strength and the yield ratio of the bolt material, respectively. Stainless steel bolts are classified into various performance grades based on the specific category of steel used, including A1-50, A1-70, A1-80, A2-50, A2-70, A2-80, A3-50, A3-70, A3-80, A4-50, A4-70, A4-80, A5-50, A5-70, A5-80, C1-50, C1-70, C1-110, C4-50, C4-70, C3-80, F1-45, and F1-60. In these designations, the first letter and number indicate the specific group of stainless steel, while the second and third numbers represent one-tenth of the tensile strength value.