Based on the different properties of the treatment process, and the different raw materials,the bolts' fracture properties under high-pressure conditions are different. First of all, the raw material strength of extension is influenced by quenching process.Normally,after general 40-degree quenching,it is difficult to achieve the raw material requirements of 10.9 high-strength bolts. If not strictly normal testing, we can check the strength of extension after the surface hardness.
Secondly, 40Cr quenched high strength bolts for raw materials mainly used in bolted ball grid frame, which design strength is generally 390MPa (d> = 30mm) or 430MPa (d <30mm).There is no high pre-use pull pressure.If want to add a high pre-tension, we need to pay attention to ensure its delayed fracture performance. High-strength bolt product quality is the key.Strictly according to the requirements is necessary.
