High - strength thread fastener product flow
High-strength thread fastener production process for the transformation of raw materials → cold heading forming → thread processing (rolling or rolling thread) → heat treatment → surface treatment → sorting packaging, 10.9 above the general use of heat treatment after rolling silk process.
Automotive fastener materials
High strength bolts commonly used steel grades for the 8.8 bolts with 35 steel, 45 steel, ML35 steel; 10.9 bolts with 35CrMo; 40Cr; 12.9 bolts with 35CrMo, 42CrMo, SCM435.
Domestic fastener raw materials are basically hot-rolled state, and like Japan and other countries of the fastener steel is basically a direct cold heading state, the user without pre-processing, from the link to reduce costs.
Common failure modes of fastener failure are assembly elongation, fatigue fracture and delayed fracture.