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<p>Brake disks made of Q355B steel on high-speed trains have exhibited severe wear under low-temperature conditions, significantly compromising operational safety. In plateau-cold and icy environments, Q355B may not be fully suitable for service. Therefore, it is essential to investigate its low-temperature mechanical properties and application range to ensure equipment safety. This study examines the mechanical behavior and failure characteristics of Q355B steel in the temperature range of 173-293&#xa0;K. Tensile tests were performed to obtain stress–strain curves, and the Johnson–Cook (J-C) constitutive model was established based on Hopkinson pressure bar experiments. Impact tests were conducted to determine failure energy, which was used to calculate the ductile to brittle transition temperature (DBTT). Fracture morphologies of impact specimens were analyzed via scanning electron microscopy, revealing temperature-dependent failure mechanisms. Finally, the J-C model and impact test results were incorporated into numerical simulations to evaluate low-temperature performance. Results indicate that as temperature decreases, both yield stress and ultimate tensile strength increase significantly, while elongation initially increases and then decreases. The DBTT of Q355B is determined to be 192.92&#xa0;K, with fracture surfaces exhibiting cleavage features at low temperatures. By integrating impact energy into the J-C model, the failure behavior of the material can be accurately simulated. These findings support the application of Q355B in low-temperature environments and improve the modeling of ductile to brittle transitions.</p>

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Research on Low-Temperature Tensile and Impact Mechanical Properties of Q355B

  • 期刊论文

  • 发表日期：

    2025年12月22日

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  • Li Shi,
  • Zhihua Sha,
  • Hexu Gao,
  • Yu Liu,
  • Shengfang Zhang

摘要

Brake disks made of Q355B steel on high-speed trains have exhibited severe wear under low-temperature conditions, significantly compromising operational safety. In plateau-cold and icy environments, Q355B may not be fully suitable for service. Therefore, it is essential to investigate its low-temperature mechanical properties and application range to ensure equipment safety. This study examines the mechanical behavior and failure characteristics of Q355B steel in the temperature range of 173-293 K. Tensile tests were performed to obtain stress–strain curves, and the Johnson–Cook (J-C) constitutive model was established based on Hopkinson pressure bar experiments. Impact tests were conducted to determine failure energy, which was used to calculate the ductile to brittle transition temperature (DBTT). Fracture morphologies of impact specimens were analyzed via scanning electron microscopy, revealing temperature-dependent failure mechanisms. Finally, the J-C model and impact test results were incorporated into numerical simulations to evaluate low-temperature performance. Results indicate that as temperature decreases, both yield stress and ultimate tensile strength increase significantly, while elongation initially increases and then decreases. The DBTT of Q355B is determined to be 192.92 K, with fracture surfaces exhibiting cleavage features at low temperatures. By integrating impact energy into the J-C model, the failure behavior of the material can be accurately simulated. These findings support the application of Q355B in low-temperature environments and improve the modeling of ductile to brittle transitions.