How the bolt strength grade is divided is based on the […]
How the bolt strength grade is divided is based on the mechanical properties. According to the relevant standards, the bolt performance grade is divided into more than 10 grades such as 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, and 12.9. Among them, grade 8.8 bolts or more are made of 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 classify the bolt strength grade → Bolt performance grade designation has two parts, which respectively represent the nominal tensile strength value and yield ratio of the bolt material. For example: a bolt with a performance rating of 4.6 means:
1. Bolt material nominal tensile strength up to 400MPa;
2. The yield ratio of bolt material is 0.6;
3, the nominal yield strength of bolt material up to 400 × 0.6 = 240MPa level
Performance grade 10.9 high-strength bolts are heat treated to achieve:
1. The bolt material has a nominal tensile strength of 1000MPa;
2. The yield ratio of bolt material is 0.9;
3, the nominal yield strength of bolt material reaches 1000×0.9=900MPa grade
Bolts: Mechanical parts, cylindrical threaded fasteners with nuts. A type of fastener consisting of two parts, the head and the screw (cylindrical with an external thread), which is required to cooperate with the nut and is used to fasten two parts with through holes.