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.

Compared with hexagon nuts, hexagon flange nuts have the same anti-skid teeth at the bottom. Except for the addition of nuts and workpieces, their dimensions and screw sizes are basically the same. Surface contact is getting stronger compared to the combination of ordinary nuts and washers. The following is the strength test of the connection box of the hexagon flange nut.