Material selection and processing technology of anchor bolts

Bolts are the most common hardware products in our daily life and play a very important role in our life. However, many people do not understand the specification and size of bolts. Today, we will give you a scientific introduction to the correct representation of anchor bolts, hoping to help you.

1. Foundation bolt material selection
Generally speaking, the material of the anchor bolt should be Q235. If the strength is not enough, the 16Mn anchor bolt can be selected through calculation. Generally, Q235 anchor bolt is used, and the bolt is tensile and pull-out resistant.    
As a matter of fact, the anchor bolts will no longer play a major role in the installed steel structure. Only part of the shear force exists, because the main function is to support after installation, so the specification should be referred to when selecting anchor bolts. In fact, we generally only use Q235B or Q235A, and generally do not use Q345 hook, with a length of no less than 150mm

Anchor bolts: they can be divided into equipment anchor bolts and structural anchor bolts. The selection of anchor bolts should be considered from the perspective of stress, that is, the shear, tensile and torsional forces borne by the fixed support bolts. At the same time, as the anchor bolts, they should mainly bear the shear force. Therefore, Q235 (also considering the environmental temperature to avoid "blue brittleness") should be selected in most cases. When the buildings, structures or equipment fixed by the local anchor bolts have obvious tension or torsion on the anchor bolts, the former should be calculated and selected with diameter or directly select 16Mn with high tensile strength, and the latter should be solved by increasing the number of anchor bolts. After all, the materials are expensive now.     

It is better to use Q235A. Q235B is more expensive than Q235A. The anchor bolts do not need to be welded, so it is OK to use Grade A.

2. Processing technology of foundation bolt material
Processing process of anchor bolt: turn the thread first, then bend the hook, and cross a Q235 with the same material length of 150mm near the hook. In addition, it should be noted that A3 is an old brand number, and now it corresponds to Q235A.A3 steel, which is the past name. Although it is still in use, it is limited to spoken language. It is better not to use it in written documents. It is Class A steel. The manufacturer of this type of steel only guarantees the mechanical performance but not the chemical composition when leaving the factory, Therefore, the impurity components such as S and P may be a little more, and the carbon content is about 0.2%, roughly equivalent to No. 20 steel, which is equivalent to Q235 in the new standard. A3 and A3F are the former names of Q235-A, Q235-A. F A3 steel and Q235, Q345 are the grades of carbon structural steel. A3 is the steel grade in the old standard, but the current standard (GB221-79) has no such grade.

In the current standard, A3 is included in Q235. Q235 represents that the yield strength of this steel is 235MPa. Similarly, 345 in Q345 can be subdivided into several categories, including: A - to ensure mechanical properties, B - to ensure mechanical properties and cold bending properties, C - to ensure chemical composition... In the old standard, the meaning of A, B, C is not much different from that in the new standard (I estimate this is the case), and 1, 2, 3...... Are used to indicate strength. 1 stands for the yield strength of 195MPa, 2 stands for the yield strength of 215MPa, and 3 stands for the yield strength of 235MPa. So A3 is equivalent to Q235A in the new brand. After all, A3 has been used before, so many people are accustomed to using it, just as others are accustomed to using the units of "jin, liang". Q235 is a carbon structural steel. Compared with the old standard GB700-79 grades, A3 and C3 Q345 are low alloy structural steel. Compared with the old standard 1591-88 grades, there are too many properties and applications of 12MnV, 16Mn 16MnRE, 18Nb and 14MnNb Q345 - shaft and weldment have good comprehensive mechanical properties, low temperature properties, good plasticity and weldability. They are used as dynamic load bearing structures, mechanical parts, building structures, and general metal structures of medium and low pressure vessels, oil tanks, vehicles, cranes, mining machinery, power plants, bridges, etc., and can be used in hot rolling or normalizing conditions. They can be used for various structures in cold regions below - 40 ℃.


Post time: Sep-23-2022