Hydrogen embrittlement fracture of bolts is a common form of failure. Because hydrogen embrittlement fracture is delayed and concealed, the damage it brings is much greater than the damage caused by other fractures. Since this century, hydrogen embrittlement fractures of alloy steel bolts have been commonplace, seriously hindering the normal development order of aerospace models, and have reached the level of "talking about hydrogen discoloration". In order to enable more scientific and technical personnel to understand the mechanism of hydrogen embrittlement, grasp the law of hydrogen embrittlement of bolts, and effectively prevent the occurrence of hydrogen embrittlement of bolts, the results of these studies are now written and introduced for readers' reference.

Screw is a combination of simple machines—it is, in essence, an inclined plane wrapped around a central shaft, but the inclined plane (thread) also comes to a sharp edge around the outside, which acts a wedge as it pushes into the fastened material, and the shaft and helix also form a wedge in the form of the point. Some screw threads are designed to mate with a complementary thread, known as a female thread (internal thread), often in the form of a nut, or object that has the internal thread formed into it. Other screw threads are designed to cut a helical groove in a softer material as the screw is inserted. The most common uses of screws are to hold objects together and to position objects.

Fastener is a kind of mechanical part which is widely used for fastening connection. It is widely used in various machinery, equipment, vehicles, ships, railways, bridges, buildings, structures, tools, instruments, chemicals, instruments and supplies. It is the most widely used mechanical foundation. It is characterized by a wide variety of specifications, different performance uses, and standardization, seriation, generalization of the degree is also very high. Therefore, some people also call a kind of fastener with existing national standards as standard fastener, or referred to as standard fastener for short.

Stainless steel fasteners We often encounter the problem of stainless steel standard parts locking. So why do stainless steel fasteners always lock up? What is the reason! Why haven't you heard that the standard parts of iron do not lock up? This may be seen from the two materials of stainless steel and iron. Stainless steel standard parts are relatively soft and have good ductility. The hardness of stainless steel standard parts is SUS316. Compared with the hardness of iron standard parts, they are softer than iron standard parts of 8.8. Fastener users often reflect: Why do stainless steel fasteners sometimes lock up, and similar phenomena do not often occur when using carbon steel fasteners, are stainless steel fasteners softer and carbon steel? Why are fasteners relatively hard? That's right! There is a fundamental difference between stainless steel and carbon steel. Stainless steel has good ductility, but its hardness is somewhat different from carbon steel.

Today we will learn the terms related to metallurgy and heat treatment:

The main purpose of surface treatment is aesthetics and corrosion protection. Because the main function of the fastener is to fasten parts, and the surface treatment also has a great impact on its fastening performance. Therefore, when selecting the surface treatment process, factors such as the torque and consistency of the pre-tightening force of the fastener must be considered.

Stainless steel machine screws are a common type of fasteners. Stainless steel machine screws break when used. What is the reason? How to identify the quality of Stainless steel machine screws? Let's take a look at the causes and quality identification methods of Stainless steel machine screws breaks. I hope to help everyone.