What are the reasons for the cracking of high-strength bolts

What are the reasons for the cracking of high-strength bolts

Stainless steel bolts, high-strength bolts, and general bolts occasionally exhibit cracking. Today, what are the key reasons for the cracking of high-strength bolts? The loosening of Threaded fastener is not due to the fatigue strength of bolts:

The Threaded fastener can only be loosened one hundred times in the transverse oscillation test and one million times in the fatigue strength test. In other words, when one ten thousandth of its fatigue strength is applied, Threaded fastener are loose. We only use one ten thousandth of its large capacity, so the looseness of Threaded fastener is not due to the fatigue strength of bolts.

The real cause of damage to Threaded fastener is looseness:

After the Threaded fastener loosens, a huge kinetic energy mv2 occurs, which directly acts on the fastener and equipment, causing damage to the fastener. After the fastener is damaged, the equipment cannot operate under normal conditions, further causing damage to the equipment.

Fasteners subjected to axial force have damaged threads and broken bolts.

Fasteners subjected to radial force, bolts are cut off, and bolt holes are punched into ellipses.

Choosing a thread locking method with excellent anti loosening effect is the fundamental solution to the problem:

At present, the most advanced and effective locking method is Dafa Threaded fastener locking method.

The large hair thread has the characteristics of both left-hand and right-hand threads. It can collaborate with both left-hand and right-hand threads.

Use two nuts with different rotation directions when connecting. The nut on the working support surface is called the fastening nut, and the A194 nut on the non supporting surface is called the locking nut. When using, pre tighten the fastening nut first, and then pre tighten the locking nut.

Under oscillation and impact conditions, the fastening nut tends to loosen. However, because the loosening direction of the fastening nut is the tightening direction of the locking nut, tightening the locking nut only avoids tightening the fastening nut. The fastening nut cannot be loosened.