These U bolts are usually in special fastening usage for railroad construction

U bolt/Specila bolt/Curved bolt

Raw material: Q235, 35K, 45#, 40Mn2, 20MnSi, 35CrMo, 40Cr, 42CrMo, etc

Grade: 4.6, 4.8, 5.6, 8.8, 10.9, 12.9

Surface: plain(oil), black, zinc, hdg, etc

U bolt, special bolt