From the appearance, it is impossible to distinguish countersunk high strength bolts from ordinary bolts. Unless it is stated that some manufacturers will mark the heads of bolts with grades 8.8, 10.9, and 12.9 in order to facilitate the distinction between high-strength bolts and ordinary bolts.
However, not all bolts with these markings on their heads indicate that they are high-strength bolts, as some manufacturers will sell low-strength bolts as high-strength bolts, so sometimes it is impossible to distinguish between them.
To truly distinguish high-strength bolts from ordinary bolts, it is necessary to distinguish them from each other in terms of torque, tensile strength, and material analysis
Under the same specification, if it is high strength, the torque, tensile strength, and hardness will be higher than those of ordinary bolts. In addition, it is also necessary to test whether the surface hardness and core hardness meet the standard. For ordinary bolts, there is a standard value. By comparing the tested standard value, you can know whether the bolt is a high-strength bolt or an ordinary bolt.
If it is to distinguish between materials, it is necessary to know which brands of bolts are commonly used for production of ordinary bolts, such as 1008 and 1010, which are generally used to produce low-grade bolts, while 10B21 and SCM435 are generally used to produce high-strength bolts. From the material composition report, you can know which type of bolt it is.
If you would like to know more methods for distinguishing countersunk high strength bolts from ordinary bolts, please feel free to contact the JINGBANG bolt manufacturer. Or if you know more ways to distinguish, welcome to communicate and discuss together!