The effect of different forging ratios on the properties and microstructures of high strength steel 40CrNi2Si2MoV

Abstract

This study combines experiments with finite element simulations to investigate the effects of different forging ratios on the properties and microstructure of high strength steel 40CrNi2Si2MoV. The results indicate that under high forging ratios, the peak of the austenite phase is significantly reduced, while the peak of the martensite phase becomes dominant, accompanied by an increase in dislocation density, strength, and hardness. The uniform distribution of newly formed small-angle martensite grains enhances both strength and plasticity. The excellent strength and toughness of high-strength steel under high forging ratios mainly depend on tempered martensite and retained austenite. The impact toughness of under a high forging ratio increases by nearly 1.23 times compared to the lower forging ratio. Additionally, the ultimate tensile strength increases by 1.02 times, the microhardness rises by 2.25 %, while the elongation decreases by 0.65 %. Fracture morphology analysis reveals that heightened forging ratios not only ensure a more uniform dispersion of carbides within the matrix but also significantly boost crack propagation resistance, thus enhancing the impact toughness of the experimental steel. The study utilizes finite element software to assess the influence of equivalent stress, equivalent strain, temperature fluctuations, and damage progression on the mechanical properties during the forging process. This comprehensive analysis establishes a robust theoretical framework aimed at optimizing both the forging process and subsequent heat treatment structures and properties of high strength steel 40CrNi2Si2MoV.

Keywords

• Forging ratio
• Microstructure
• Mechanical properties
• Numerical simulation
• High strength steel