The unified Dacromet surface coating shall be adopted for the surface treatment of segment bolts of Dalian shot blasting shield, which can ensure the mechanical performance and quality of fasteners, and its anti rust performance is good. It is believed that as long as the supervision department clearly attaches importance to the rust prevention requirements and carries out "three coats and three seals"! The bolts are rustproof Blackening and galvanizing can be used. Try not to damage the phosphating layer and paint during installation. Hexagonal screw sleeve should be considered during installation to make the surface stress uniform, so as not to damage the protective layer. It can also be considered to spray paint after installation, or use stainless steel bolts. Dacromet should be good in stainless steel bolts, but it can also be coated with some dural antirust oil. Blackened parts can be antirust for a short time, but improper subsequent treatment will cause more serious corrosion