How to determine whether a screw is a high strength screw or a normal screw?

It is literally understood that high strength screw is subjected to loads greater than ordinary screws of the same specification. However, professionally, the distinction between high-strength screws and ordinary screws is distinguished by performance level.

According to the performance grade of the screw, it is divided into more than 10 grades of 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9, etc., but only the screw grade is 8.8 grade and above. The screw material is low carbon alloy steel or medium carbon steel. After heat treatment (quenching, tempering), it can be called high strength screw, and the rest is called ordinary screws.

The meaning of the screw performance grade is the international standard. The screw of the same performance grade has the same performance regardless of the difference between the material and the place of origin. Only the performance grade can be selected in the design. In terms of appearance, it is difficult to distinguish between the two. The high strength screw is many times stronger than the ordinary screw, and the repeated utilization rate is higher than the ordinary one.

When we can’t make a difference in appearance, we usually distinguish them by testing. Generally, through the torque test, different levels of screws, their torque range is also different.

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