Quantitative Characterization of Tensile Strength for Carburized Materials Using a Novel Composite Strength Method

Carburizing is a cost-effective surface hardening process that significantly enhances the strength of components and is widely used in critical parts such as main transmission gears and cams. However, research on mathematical models for characterizing the strength of carburized layers remains underdeveloped, limiting the accurate assessment of the service strength of carburized workpieces. To address this issue, this study focuses on 20CrNiMo steel and proposes a novel composite strength method for the quantitative prediction of the tensile strength of carburized specimens. By establishing a continuous mapping function between microhardness measurements and tensile strength distribution, and developing an equivalent strength mathematical model for non-uniform carburized gradient structures, the proposed method successfully predicts the strength of specimens under different carburizing depths. This approach represents a departure from the conventional Voigt-based paradigm, which relies on layered discretization of the carburized zone for approximate estimation, leading to significant improvements in both predictive efficiency and accuracy. Based on experimental data, the proposed method achieves a reduction in prediction errors of over 41.8% compared to traditional multilayer methods. In summary, this study not only provides a reliable and efficient computational tool for the quantitative characterization of carburized steels, but also demonstrates strong potential for application in the strength assessment and design optimization of critical engineering components.