The quenching process has a direct influence on the maximum tensile strength of the materials used to make high-strength bolts. In most cases, it is extremely challenging to satisfy the material requirements of 10.9s-grade high-strength bolts after the 40Cr quenching treatment has been applied. After being quenched, the material's surface hardness can be used in tests with a lower standard of precision to estimate the maximum tensile strength of the material. In addition to their distinct characteristics when being processed under high levels of stress, the delayed fracture properties of high-strength bolts made of different materials are distinct from one another.
High-strength 40Cr bolts are typically utilized for the assembly of bolted ball joint grids. There is no high prestress involved, and the design strength is typically 390mpa (d=30mm) or 430mpa (d30mm). When subjected to high pretension, caution is required to ensure that its delayed fracture properties are understood and maintained. When it comes to delayed fracture performance, high-strength Eye Bolts made of 20MnTiB perform significantly better than those made of 40B.
According to GB/t1231-91, the materials 20MnTiB (applicable specification = M24) and 35VB (applicable specification = M30) are the ones that are recommended for use in the production of 10.9s bolts. Large-diameter high-strength bolts are difficult to harden when subjected to the quenching treatment. Because of this, large-diameter high-strength bolts are generally not recommended for use; however, if you insist on utilizing them, their working stress should be lowered.(GB799, L-shaped bolts, and the like are capable of producing thread diameters ranging from 6-120mm; the length of the bolts is not restricted; the following materials may be used: Q235, 45Q, Q345B, 40Cr, 35CrMoA, etc. The anchor bolts are able to be subdivided into the following categories: straight hook type, arc hook type, Anchor melon type, reinforced anchor plate type, Q235 type, 35 steel feet, including 24,000 sets of high-strength bolts, material 40, 0 sets of high-strength bolts 210), composed of 2 open channels in the Tongjiezi Project, and the steel beams of the concrete construction trestle have been installed and put into.
The bolts used in the construction of the steel structure are of a particularly high strength.
10.9 grade friction type connection torsion shear type high strength bolt material with an 045 friction coefficient.20 manganese titanium boron (20MnTiB) nut material15 manganese vanadium boron (15mnvb)In accordance with which national standard does this bolt operate? How to make requirements to the manufacturer when purchasing a steel structure that conforms to GB/T3632-2008. Bolts, screws, and studs made of carbon steel and alloy steel must have the following mechanical property markings:
(1) Bolts, screws, and studs made of carbon steel and alloy steel have 10 performance grade codes (thread diameter 1.6-39mm, working temperature -50°C-300°C), 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°C). Working temperature of bolts, screws, and studs made of carbon steel and alloyThe bolts of grade 8.8 and higher are either made of low-carbon alloy steel or medium-carbon steel. This is true one way screws for all of them. After undergoing heat treatment, which typically consists of quenching and tempering, these bolts are referred to as high-strength bolts, whereas the rest of the bolts are typically referred to as ordinary bolts.
(2) The bolt performance grade mark consists of two parts of numbers. These parts of numbers represent, respectively, the nominal tensile strength value of the bolt material and the yield strength ratio of the bolt. For instance, if a bolt has the property class 4.6, it means the following:
1. The bolt material has a nominal tensile strength of 400 MPa; 2. The yield strength ratio of the bolt material is 0.6; 3. The nominal yield strength of the bolt material is 400 minus 0.6, which equals 240 MPa.
The performance grade is 10.9 high-strength bolts, and the following are some of the capabilities of the material:
4. The bolt material has a tensile strength that can reach 1000 MPa at its nominal value.
5. The nominal yield strength of the bolt material is 1000 multiplied by 0.9, which equals 900 MPa. 6. The yield strength ratio of the bolt material is 0.9.
An international standard is what is meant when we talk about the bolt performance grade. The performance of bolts of the same performance grade is the same, regardless of the material or origin, and the design only allows for the selection of performance grades.
The majority of high-strength fasteners take the form of bolts with increased tensile strength. Bolts that are considered to be high-strength are either made of high-strength steel or require a greater amount of preload. The majority of the time, high-strength bolts are utilized to connect high-voltage and ultra-high-voltage equipment, as well as bridges and railways. The crack in the bolt has a very brittle appearance.
Throughout the 1990s, continuous heat treatment lines maintained their position as an industry standard. The heat treatment and tempering of smaller and medium-sized fasteners is an application that lends itself particularly well to the impact bottom mesh furnace. In accordance with the pertinent technical requirements, high-strength bolts are required to be quenched. The purpose of the quenching heat flat head screws treatment is to improve the mechanical properties of fasteners in order for them to meet the requirements of having a tensile strength that is greater than a predetermined value and having a product qualification rate of at least a certain percentage.
When it comes to the internal quality of high-strength fasteners, the heat treatment process plays an extremely important role. Therefore, in order to manufacture fasteners of a high quality and high strength, it is necessary to have cutting-edge technology and equipment for the heat treatment process. The mass production of high-strength bolts, along with their low price, fine thread, and precise structure, necessitates that the heat treatment equipment have a large production capacity in addition to a high degree of automation.
The quality of the heat treatment is satisfactory. Automatic controls are utilized throughout the cleaning, heating, quenching, cleaning, tempering, decolorization, and coloring processes of the high-strength fasteners that are distributed, which effectively guarantees the quality of the heat treatment. Decarburization is sometimes caused by threaded fasteners. They will trip first when they are unable to meet the mechanical performance requirements, which will result in the failure of threaded fasteners and a reduction in the service life of the fasteners. If the annealing process is not carried out in the correct manner, the layer of the raw material that has been decarburized will become deeper as a result of the decarburization of the raw material. In the process of heat treatment, also known as tempering heat treatment, it is common practice to bring in some oxidizing gas from the outside of the furnace.