How the bolts are graded are divided according to mechanical properties. According to the relevant standards, the bolt performance grade is 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9 and so on, among which 8.8 and above are low carbon alloy steel or medium carbon steel and heat treated (Quenching, tempering), commonly known as high-strength bolts, the rest known as ordinary bolts.
How to divide the bolt strength grade → Bolt performance grade The label has two parts, which represent the nominal tensile strength and yield ratio of the bolt material, respectively. For example: the performance level of 4.6 bolts, its meaning is:
1, the bolt material nominal tensile strength of 400MPa level;
2, the strength ratio of the bolt material is 0.6;
3, the nominal strength of the bolt material strength of 400 × 0.6 = 240MPa level
Performance grade 10.9 high-strength bolts, the material after heat treatment, to achieve:
1, the bolt material nominal tensile strength of 1000MPa level;
2, the strength of the bolt material ratio of 0.9;
3, the nominal strength of the bolt material strength of 1000 × 0.9 = 900MPa level
Bolts: Mechanical parts, threaded threaded fasteners with nuts. A type of fastener consisting of a head and a screw (with a threaded cylinder) is fitted with a nut for fastening the connection of two parts with through holes.