Why does China need a lot of imported high-end bolts?

The bolts look simple, and in fact the high-end bolts are really not simple. This starts with the technical requirements for bolts in high-end applications. The technical requirements for bolts for high-end applications are as follows: 1. Corrosion resistance requirements, measured by the number of hours of salt spray resistance test, generally require more than 720 hours; 2. Strength requirements; 3. Tightening torque consistency requirements.