What kind of material are high strength bolts made of?

       1、 The maximum tensile strength of materials for high strength bolts is closely related to quenching treatment. After 40Cr quenching treatment, it is difficult to meet the material requirements of 10.9s grade high strength bolt. In less strict inspection, the maximum tensile strength of the material can be determined according to the surface hardness after quenching. In addition to the different properties in the process of treatment, the delayed fracture performance of high-strength bolts made of different materials is also different under high stress.
       2、40Cr high-strength bolt is mainly used for bolted sphere joint space truss. Its design strength is generally 390mpa (d > = 30mm) or 430mpa (d < 30mm), and there is no high prestress in use. In the case of high pretension, attention should be paid to understand and ensure 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 high-strength bolt is not easy to harden, so generally do not use large diameter high-strength bolt, if you want to use it, you should reduce its working stress.
       (gb799, L-bolt, etc., can produce thread diameter of 6-120mm, unlimited length, material: Q235, 45 × Q, Q345B, 40Cr, 35CrMoA, etc., anchor bolt can be divided into straight hook type, arc hook type, anchor melon type, stiffening anchor plate type, Q235 type, 35 × steel foot, including 24000 sets of high-strength bolts, 40 materials, 210 "high-strength bolts) 0 sets, consisting of two open channels of Tongjiezi project, concrete construction stack The steel beam of the bridge has been installed and put into use. The layout of the two bridges is as follows (Figure 1): 1. Steel structure is connected by high-strength bolts
       Friction coefficient of 10.9 grade friction type connection torsional shear type high strength bolt 045 bolt material 20 manganese titanium boron (20MnTiB) nut material 15 manganese vanadium boron (15mnvb) what national standard does the bolt adopt? How to put forward requirements to the manufacturer when purchasing GB / t3632-2008 steel structure
       Marking of mechanical properties of carbon and alloy steel bolts, screws and studs:
       (1) Carbon and alloy steel bolts, screws and studs have 10 performance level 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 (working temperature of free cutting steel bolts, screws and studs shall not exceed 250 ℃). Among them, grade 8.8 and above bolts are made of low-carbon alloy steel or medium carbon steel. After heat treatment (quenching and tempering), they are generally called high-strength bolts, and the rest are generally called ordinary bolts.
       (2) The performance grade mark of bolt consists of two parts of numbers, which respectively represent the nominal tensile strength value and yield strength ratio of bolt material.
       For example, a bolt with a performance class 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. The nominal yield strength of bolt material is 400 × 0.6 = 240 MPa
       The performance grade is 10.9 high strength bolt, and the material can reach:
       4. The nominal tensile strength of bolt material can reach 1000MPa
       5. The yield strength ratio of bolt material is 0.9;
       6. The nominal yield strength of bolt material is 1000 × 0.9 = 900MPa.
       The meaning of bolt performance grade is international general standard. For bolts of the same performance grade, regardless of the material and place of origin, the performance is the same, and only the performance grade can be selected in the design.