45# Steel

45# steel is a mainstream high-quality medium-carbon structural steel widely used in the mechanical processing industry. It features stable material composition, excellent overall mechanical performance, and superior cutting, machining and forming properties, which can fully meet the production and processing requirements of most conventional structural parts and mechanical components. This steel grade boasts balanced rigidity, toughness and plasticity, with reliable comprehensive performance and stable batch consistency, making it one of the most cost-effective and versatile structural steel materials in factory mass production.

The material exhibits distinct hardness characteristics before and after professional heat treatment. In its raw state without heat treatment, the hardness of 45# steel is controlled within 197 HB, with moderate hardness and excellent machinability, convenient for turning, milling, drilling and other precision machining operations. After high-standard quenching treatment, the surface and internal hardness of the steel can be greatly improved, reaching a hardness range of HRC 55–62, which effectively enhances the surface wear resistance and structural rigidity of parts. Subsequent tempering treatment can eliminate internal stress generated during quenching, stabilize the material structure, and fix the final hardness at HRC 42–46, achieving an optimal balance between hardness and toughness. In terms of core mechanical properties, factory test data shows that 45# steel has excellent structural bearing capacity. Its tensile strength is no less than 600 MPa, yield strength reaches more than 355 MPa, the elongation rate is ≥16%, and the section shrinkage rate is ≥40%. In addition, the material has outstanding impact toughness, with an impact energy Akv ≥39 J and impact toughness akv ≥49 J/cm². It can withstand frequent mechanical impact and alternating load operation, avoiding brittle fracture and structural deformation, and ensuring the long-term stable service life of mechanical parts.

Our factory adopts standardized and mature quenching and tempering (QT) composite heat treatment process to further optimize the comprehensive performance of 45# steel workpieces. The standardized process flow is strictly implemented in accordance with industrial production standards: first, normalizing treatment at 850°C to refine the grain structure and homogenize the material performance; then quenching at 840°C to strengthen the overall hardness and wear resistance of the parts; finally, high-temperature tempering at 600°C to remove processing stress, improve material toughness and prevent part cracking and deformation.

After standardized heat treatment, 45# steel workpieces achieve more balanced and stable mechanical properties, with greatly improved load resistance, fatigue resistance and structural stability. Relying on its superior comprehensive performance, this material is widely used for processing and manufacturing medium-load mechanical components, including various precision shafts, transmission gears, automobile chassis structural parts, mechanical equipment accessories and building structural components. With stable material quality, reliable processing performance and low comprehensive production cost, 45# steel has become the preferred material for mass processing and customized production in machinery manufacturing, automobile processing, engineering construction and other industries.