Ordinary bolts are generally made of ordinary carbon structural steel without heat treatment. High strength bolts are generally made of high-quality carbon structural steel or alloy structural steel. They need to be quenched and tempered heat treatment to improve their comprehensive mechanical properties. High strength is divided into grade 8.8, grade 10.9 and grade 12.9. From strength grade: high strength bolts usually have two strength grades: 8.8s and 10.9s.

普通螺栓一般有4.4级，4.8级5.6级8.8级。从受力特点高强螺栓施加预拉力和靠摩擦力传递外力，普通螺栓靠栓杆抗剪力和孔壁承压来传递剪力。钢结构螺栓有两种连接方法，一种是高强度螺栓冷加工连接方法，另一种就是高强度螺栓热加工连接的方法。、

Ordinary bolts generally have grade 4.4, grade 4.8, grade 5.6 and grade 8.8. From the stress characteristics, high-strength bolts exert pretension and transmit external force by friction, while ordinary bolts transmit shear by bolt rod shear resistance and hole wall pressure. There are two connection methods for steel structure bolts, one is the cold working connection method of high-strength bolts, and the other is the hot working connection method of high-strength bolts.

我们在生产加工的时候可以按照使用的时候不同的要求来做选择，冷加工连接是刚性的连接，而热加工连接的是柔性连接。

We can choose according to different requirements during production and processing. Cold working connection is rigid connection, while hot working connection is flexible connection.