The advantages of
cold drawn carbon steel include high precision, high mechanical properties, which are widely used in the automotive industry. The mechanical properties of this type of cold drawn steel are strict, and it has strong tensile strength compared with ordinary
carbon steel. And the yield strength, elongation after break, hardness and other performance indicators are higher than the national standard. The strength index of the production process after annealing, straightening, drawing and polishing according to the conventional process route can reach 550 MPa or more. Many users require higher performance steel to increase the life of the workpiece. By improving the surface reduction rate before the finished product is processed, the performance index can reach 720 MPa, especially the tensile strength reaches 750 MPa or more. According to the previous process route, the tensile strength of the finished product is up to 700MPa, which is for the production of high mechanical tensile strength 735MPa to 900MPa, yield strength ≥430MPa, elongation after fracture ≥7%, hardness HB210-HB265, such as cold drawn steel material C45.
The steel after cold drawing deformation is heated to a certain temperature after aging heat treatment for heat preservation. Since the steel after cold drawing has a metastable structure, the mechanical properties and physical properties of the steel change with the increase of the holding time at a certain temperature, and there is no significant change in the microstructure of the steel to achieve improvement to improve mechanical properties and reach the purpose of stabilizing steel size and shape. The strength of the cold drawn steel after aging is improved, and it is considered that the fine particles such as cementite and oxide which are decomposed in the ferrite inside the steel strengthen the steel. Regarding the aging treatment temperature, the furnace and the steel type in the production process can be used according to the specific conditions, and some adopt aging treatment at 200°C to 300°C or 380°C to 400°C, and also adopt higher temperature. When the steel material is heat-treated, the steel material heat-treated by the same heat treatment system can be treated in the same furnace for convenience, and the mechanical properties of India and steel are analyzed by representative samples, and the analysis is continuously improved to help users obtain the products they need.