Open expansion ring and cause of hydrogen embrittlement

1. The spring washer has a dilatation phenomenon, which is generally not a problem with the spring washer itself.

2. The spring washer in which the expansion ring occurs is inevitably subjected to a radial external tension, and the external tension is derived from the tightening axial force generated by the tightening torque.

3. The outer chamfer of the nut bearing surface causes a radial component force in the axial clamping force, thereby causing the opening of the spring washer to expand. The smaller the chamfer diameter, the more likely the expansion ring will occur.

4. Adding a flat washer between the nut and the spring washer helps to slow or prevent the expansion of the ring, but the flat washer is too thin or too soft to prevent the expansion ring from occurring.

5. The reasons for the hydrogen-brittle brittle fracture of the spring washer are generally that the heat treatment process is unreasonable and that the fracture is caused by the dehydrogenation treatment after the electroplating of zinc.