What material is generally used for high-strength bolts?

What material is generally used for high-strength bolts?

1. The maximum tensile strength of materials for high strength bolts is closely related to quenching treatment. After 40Cr quenching treatment, it is generally difficult to meet the material requirements of 10.9s grade high-strength bolts. In less stringent inspection, the maximum tensile strength of the material can be determined according to the surface hardness after quenching treatment. High strength bolts of different materials have different delayed fracture properties in addition to their different properties in the process of treatment under high stress.

2. 40Cr high-strength bolts are mainly used for bolt ball joint space truss, and their design strength is generally 390mpa (d>=30mm) or 430mpa (d<30mm), without high prestress in use. When used under high pretension, attention should be paid to understanding and ensuring its delayed fracture performance. The delayed fracture performance of 20MnTiB high strength bolt is better than that of 40B.

3. According to gb/t1231-91, the recommended materials for 10.9s bolts are 20MnTiB (applicable specification<=m24) and 35VB (applicable specification<=m30). In quenching treatment, large diameter and high strength bolts are not easy to harden, so generally do not use large diameter and high strength bolts. If it is to be used, its working stress should be reduced.

(gb799, L-type bolt, etc., can produce thread diameter of 6-120mm, unlimited length, material: Q235, 45 × Q. Q345B, 40Cr, 35CrMoA, etc. anchor bolts can be divided into straight hook type, arc hook type, anchor melon type, stiffening anchor plate type, Q235 type, 35CrMoA type, etc × Steel feet, including 24000 sets of high-strength bolts, 40 materials, 210 ") 0 sets of high-strength bolts, are composed of two open channels of Tongjiezi project. The steel beams of the concrete construction trestle have been installed and put into use. The layout of the two bridges is as follows (Figure 1): 1. The steel structure is connected by high-strength bolts

Grade 10.9 friction type connection torsion shear type high strength bolt friction coefficient 045 bolt material 20 manganese titanium boron (20MnTiB) nut material 15 manganese vanadium boron (15mnvb) what national standard is adopted for the bolt? How to put forward requirements to the manufacturer when purchasing gb/t3632-2008 steel structures

Marking of mechanical properties of carbon and alloy steel bolts, screws and studs:

(1) Carbon steel and alloy steel bolts, screws and studs have 10 performance grade codes (thread diameter 1.6-39mm, working temperature -50 ℃ -300 ℃), including 3.6, 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 10.9 and 12.9 (the working temperature of free cutting steel bolts, screws and studs shall not exceed 250 ℃). Among them, bolts of grade 8.8 and above are made of low-carbon alloy steel or medium carbon steel, which are generally called high-strength bolts after heat treatment (quenching and tempering), and the rest are generally called ordinary bolts.

(2) The bolt performance grade mark is composed of two parts of numbers, representing the nominal tensile strength value and yield strength ratio of bolt material respectively.

For example, a bolt with a performance grade of 4.6 indicates:

1. The nominal tensile strength of bolt material reaches 400MPa;

2. The yield strength ratio of bolt material is 0.6;

3. Nominal yield strength of bolt material reaches 400 × 0.6=240mpa

The performance grade is 10.9 high strength bolt, and the material can reach:

4. Nominal tensile strength of bolt material can reach 1000MPa

5. The yield strength ratio of bolt material is 0.9;

6. Nominal yield strength of bolt material is 1000 × 0.9=900mpa.

The meaning of bolt performance grade is an international general standard. For bolts with the same performance grade, the performance is the same regardless of the material and origin, so only the performance grade can be selected in the design.