Before understanding the bolt grades, we need to first know what hardness ordinary bolts have. The 4.8-grade bolts are almost used in both household and daily life. For the assembly of ordinary furniture, lightweight shelves, motor housing fixation, ordinary boxes, and some non-structural civilian products, they can all handle the task. Lug bolts of grade 8.8 can already be applied in common industrial scenarios such as automobile manufacturing, steel structure factories, bridges, towers, heavy cargo vehicles, and large pipeline supports. 12.9-grade bolts can be applied to large ships, aerospace shells, etc. These three types of bolts almost cover all of human modern industry.
The strongest type of bolt available in the market is the 12.9 grade.
Shanghai University of China in 2021 developed bolts that have reached a grade of 19.8. The tensile strength is 1900 – 2070 Mpa.
However, it has not yet entered the commercial promotion stage. This might be related to the implementation and deployment of the production equipment, as well as the technical difficulty.
This type of bolt of such hardness will be of great help to scientific research and development.
However, such bolts are not yet applicable in the current market environment.
Commercial bolts of grade 8.8 and 12.9 have become the mainstream products used in the automotive and aerospace industries, and are also the products explicitly stipulated and used in design specifications.
It is hoped that the industrial development of mankind can continue to progress. When our industry required 19.8-grade bolts as the industry standard and specification, our industrial development also reached a new level.
Post time: Dec-31-2025
