The difference between Bolts

Update:07-06-2018
Summary:

Under normal circumstances, high-strength bolts can wit […]

Under normal circumstances, high-strength bolts can withstand larger loads than normal bolts of the same specification.
Ordinary bolts are made of Q235 (A3).
High-strength bolt material 45 # steel, alloy steel (such as 20MnTiB, 35VB) or other high-quality materials, made of heat treatment, increased strength.
The difference between the two is the difference in material strength.

The first point: From raw materials:
High-strength bolts are made of high-strength materials. The bolts, nuts and washers of high-strength bolts are made of high-strength steel. They are commonly used in No. 45 steel, 40-boron steel and 20-manganese-titanium-boron steel. Ordinary bolts are commonly made of Q235 steel.
The second point: From the strength level:
High-strength bolts are used more and more widely. Commonly used 8.8 and 10.9 two intensity levels, of which 10.9 mostly. Ordinary bolt strength level is low, generally 4.4, 4.8, 5.6. (8.8S and 10.9S are special for steel structures)Non-Standard Bolts

The wire used for high-strength bolts is No.45 steel, etc. For the heat treatment of this screw, C1035 is used for hardening treatment. This hardening method can generally achieve a high strength of 22--32HRC.
For this type of high-strength bolt, the 8.8-level corresponds to the 8-stage nut, and the 10.9-level corresponds to the 10-stage nut. Many people will ask why the use of nuts is lower than the hardness of screws? There is a reason for this. During use, in order to be able to protect high-strength bolts and prolong their service life, there must be certain wear during the process of continuous disassembly. When the hardness of the 8-stage nut is relatively low, it can be effective. The protection to the screw, in the use of such fasteners, such a combination is more reasonable, just like the hardness of the wrench compared to the hardness of the wrench when the highest is the same reason.
It can be said that the production of high-strength bolts has a very high level. Today, high-strength bolts are widely used in the industry and in the automotive industry. The technical requirements for the production of such screws are also increasing.