Bolts are mechanical connectors that are widely used in various industries, but perhaps some consumers do not know that bolts actually have strength levels. The strength level of the bolt is closely related to the use of the bolt. This article will be around the bolt strength level to explain, I hope to help you.
The strength grades of bolts used for steel structure connection are as follows :3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9 and other more than 10 grades. The bolt strength grade label is composed of two numbers, respectively, indicating the nominal tensile strength and flexion ratio of the bolt material. For example, a 4.6 bolt means: 1. The nominal tensile strength value of the bolt material is 400MPa; 2. The bending ratio of bolt material is 0.6; 3. The nominal yield strength of the bolt material is 400×0.6=240MPa.
The meaning of the bolt strength grade is an international standard, and the same performance grade of the bolt, regardless of its material and origin, its performance is the same. Therefore, as long as the corresponding performance level is selected in the design. The strength grades of bolts are usually expressed as numbers, such as grades 8.8 and 10.9, and the numbers indicate that the shear stress grades of the bolts are 8.8GPa and 10.9Gpa, respectively. The specific meaning of 8.8 and 10.9 bolts The nominal tensile strength of 8.8 bolts is 800N/mm. , nominal yield strength of 640N/mm? . The 10.9 bolt is after special heat treatment to achieve the following three performance indicators: 1. The nominal tensile strength of the bolt material is 1000MPa; 2. The bending ratio of bolt material is 0.9; 3. The nominal yield strength of the bolt material reaches 900MPa. How to calculate the strength level of a bolt The strength level of a general bolt is expressed in X.Y. Where X*100 represents the tensile strength of the bolt, and X*100*(Y/10) is the yield strength of the bolt, where Y represents the ratio of yield strength to tensile strength. For example, class 4.8 indicates that the tensile strength of the bolt is 400MPa, while the yield strength is 400*8/10=320MPa. In the selection of bolts, it is particularly important to understand the strength level of bolts. Accurate judgment and calculation can help us to buy and use more suitable bolts, so as to better ensure the safety and stability of our work.
