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 fasteners is not due to the fatigue strength of the bolts:

Threaded fasteners can only be loosened one hundred times in the lateral oscillation experiment, and one million times in the fatigue strength experiment. In other words, when one tenth of its fatigue strength is applied, threaded fasteners are loose. We only use one tenth of its large capacity, so the loosening of threaded fasteners is not due to the fatigue strength of the bolts.

The true cause of damage to threaded fasteners is looseness:

After the loosening of threaded fasteners, a huge kinetic energy mv2 occurs, which directly affects the fasteners and equipment, causing damage to the fasteners. After the fasteners are damaged, the equipment cannot operate normally, further leading to equipment damage.

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:

Nowadays, the most advanced and effective anti loosening method is the Da Fa threaded fastener anti loosening 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.

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