Most of the structural seamless steel pipes work under relatively large dynamic loads. They are subjected to tension, compression, bending, torsion or shearing. Some surfaces also have friction, requiring certain wear resistance and so on. In summary, parts operate under various compound stresses. Structural seamless steel pipes are mainly structural parts of various machines and mechanisms, such as shafts, connecting rods, studs, gears, etc., and are widely used in the manufacturing industries such as machine tools, automobiles and tractors. Especially for large parts in heavy machinery manufacturing, quenching and tempering treatment is used more. Therefore, the quenching and tempering treatment of structural seamless steel pipes occupies a very important position in heat treatment.
The quenched and tempered parts in mechanical products have different performance requirements because of their different stress conditions. Generally speaking, all kinds of quenched and tempered parts should have excellent comprehensive mechanical properties, that is, the appropriate combination of high strength and high toughness, so as to ensure the long-term smooth operation of the parts.
Quenching and tempering of structural seamless steel pipes usually refers to the heat treatment process of quenching + high temperature tempering to obtain tempered sorbite. The method is to quench first, and the quenching temperature: hypoeutectoid steel is Ac3+30~50℃; hypereutectoid steel is Ac1+30~50℃; alloy steel can be slightly higher than carbon steel. After quenching, it can be tempered at 500~650℃. The main purpose of quenching and tempering is to obtain comprehensive mechanical properties with good strength and plasticity.
The quenched and tempered structural seamless steel pipe has good comprehensive mechanical properties and is widely used in various important structural parts, especially those connecting rods, bolts, gears and shafts that work under alternating loads. But the surface hardness is low and not wear-resistant. Quenching and tempering + surface quenching can be used to improve the surface hardness of parts.
Permanent Steel Manufacturing Co.,Ltd as a carbon steel tube supplier, has years of experience in manufacturing of carbon steel pipe, stainless steel tube, hollow section, pipe fittings. (Fluid Pipe/Boiler Tube/Fire Pipe/Line Pipe/Structure Tube)