Effect of Annealing Process on Tensile Strength of 45Mn2 Steel for Insulator Pin

To investigate the influence of different annealing temperatures on the tensile strength of 45Mn2 steel insulator pin and optimize annealing process parameters, annealing experiments were conducted at 480, 540, 560, 580, and 620°C on 45Mn2 steel insulator pin. Tensile tests were performed on 10 samples per group, and the strength and process stability were evaluated using the arithmetic mean and standard deviation. Results show that the tensile strength decreases approximately linearly with increasing annealing temperature, dropping from 667.4 kN at 480°C to 602.0 kN at 620°C, a reduction of 9.8%. After annealing at 580°C, the average tensile values of two tests were 648.6 kN and 647.6 kN, with standard deviations of 6.74 and 7.11, respectively, the lowest among all temperature groups, indicating optimal process stability. Batch production verification revealed average values of 654.12 kN for heat-treated pin and 660.37 kN for finished products, both stable within the target range of 630–680 kN. Consequently, 580°C is determined as the optimal annealing temperature for 45Mn2 steel insulator pin, with recommended parameters of 580±5°C for 2.5 hours, followed by air cooling.