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Fastener Material Requirements
Aug 16, 2017

According to the China Automobile Industry Association in January 2010 statistics, in 2009 China's automobile production and sales were 1379.10 million and 1364.48 million, Fastener respectively,Fastener year on year increase of 48% and 46%. The rapid development of the automotive industry has increased the demand for steel materials, although China has continued for many years as the world's largest steel producer, but the automotive engine and key components of fasteners due to the strength of the restrictions or imported products, Fastener The high performance and lightweight development trend of the automobile, the design stress and light weight of the car fastener put forward higher requirements, fastener steel high strength is to solve this requirement is the most effective way.

Automotive fasteners steel requirements:

Has a good surface quality, high-level dimensional accuracy and low-grade non-metallic inclusions and segregation;

Has a high tensile strength and good cold heading performance;

Has a high fatigue resistance and multiple impact tensile resistance;

Has a sufficiently low delayed fracture sensitivity and a lower toughness - brittle transition temperature.

The use of furnace refining and electromagnetic mixing with the casting process. Mainly in the steel of C, Si, Mn, Cr, Mo and other major elements of the control in a small range, and as much as possible to reduce the steel P, S, 0, N and other impurities, Fastener to achieve high purity steel, Fastener 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. The same time as

A 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. The same time as

From the steel to improve the cold heading, Fastener improve the steel is concerned, the need to minimize the content of impurities in steel impurities. Reducing the S content can improve the deformation ability of the steel and reduce the non-metallic inclusions in the steel to improve the toughness. Reduce the P content to reduce the deformation resistance of the steel while reducing the P and S content can also reduce its segregation at the grain boundary Reduce the grain boundary embrittlement, Fastener and can improve the steel resistance to delayed fracture performance; Fastener reduce the steel 0 content, can effectively reduce the oxide inclusions, Fastener thereby improving the steel cold working deformation capacity.

The KISCC of steel with high cleanliness is higher than that of commercial steel. Therefore, in order to ensure that the steel is still strengthened after high strength, the strength of the stress corrosion factor KISCC of ML42CrMo steel with high cleanliness is studied. Fastener With a high overall performance, Fastener high strength bolts steel P, S content to be further reduced.

The use of micro-alloy non-quenched and tempered steel manufacturing bolts can be omitted before the cold-drawn bolts bolts and bolts after forming the quenching and tempering treatment, Fastener but also reduce the deduction of thread deduction tendon, improve the yield of bolts, economic benefits are obvious The

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