Meaning Of Bolt Property Classes

According to relevant standards, the property classes for carbon steel and alloy steel bolts include over ten grades, such as 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, and 12.9. Bolts of class 8.8 and above are made from low-carbon alloy steel or medium-carbon steel and undergo heat treatment (quenching and tempering); these are generally classified as high-strength bolts, while the others are classified as ordinary bolts. The property class designation consists of two parts: the first indicates the nominal tensile strength of the bolt material, and the second indicates the yield-to-tensile strength ratio. Stainless steel bolts are categorized into various property classes based on steel type, such as 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 initial letter and number represent the stainless steel group, while the subsequent two digits represent one-tenth of the tensile strength value.