1, Automotive fasteners steel requirements
Good surface quality, high-level dimensional accuracy and low-grade non-metallic inclusions and segregation
High tensile strength and good cold heading performance
High fatigue resistance and multiple impact tensile resistance
Sufficiently low delayed fracture sensitivity and a lower toughness - brittle transition temperature.
     2, Automotive fastener steel smelting and rolling characteristics
2.1, Smelting technology
Adopting the technology of  furnace refining and electromagnetic mixing with the casting process. Mainly controling the steel of C, Si, Mn, Cr, Mo and other major elements in a small range, and try best to reduce the steel P, S, 0, N and other impurities, to achieve high purity steel, Non-metallic inclusions are low and the segregation level is low.Thereby improving the cold heading performance of the steel and improving the surface quality of the steel.
2.2, Rolling technology
High-speed, high-precision rolling process with controlled dairy and controlled cooling is used to obtain hot-rolled wire rods with good dimensional accuracy and as little surface defects as possible.
Automotive fasteners steel status and development direction
     3, Automotive fasteners steel status and development direction
3.1, Clean bolt steel
3.2, Economic high-strength bolt steel
3.2.1, Micro-alloy non-quenched and tempered steel
3.2.2, Non-annealed medium carbon steel or medium carbon alloy steel
3.2.3, Boron steel
3.2.4 High tensile strength resistant to delayed fracture
     The rapid development of the Chinese automotive industry has brought great market opportunities to the domestic automotive fasteners. And automotive fasteners with high-strength steel has become the inevitable trend of market development.Conditional Chinese steel companies should speed up the steel research and production of car fasteners with steel research.Learning from the foreign advanced production technology to improve the automotive fastener steel localization rate.