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<p>Creep behaviors of high strength structural steels (HSSSs) may lead to progressive collapse of high-rise buildings that widely use HSSSs as material of load-bearing components in incident fires. However, their high-temperature creep mechanisms and damage modes remain unclear, and predictive models of creep life are lacking. This study analyzes the creep rupture data of Q550, Q690, Q890 and Q960 HSSS (including Q690 in both quenching and tempering (QT) and thermal–mechanical control process (TMCP) followed by quenching and tempering (TMCP-QT)) to investigate their creep mechanisms, fracture modes and prediction of creep life. The results show that the creep mechanism of HSSS below 600&#xa0;°C is power law breakdown creep, whereas a transition in creep mechanism occurs as the temperature above 600&#xa0;°C. In QT HSSS, creep damage is dominated by power-law and diffusion creep, necking, and microstructural degradation, leading to cavity growth. In TMCP-QT HSSS, damage is associated with reduced dislocation density, precipitate formation, and subgrain coarsening. The Larson-Miller (LM) and Orr-Sherby-Dorn (OSD) methods predict QT HSSS creep life with with about 20% error. For TMCP-QT, LM has a 20% error, while OSD’s error is around 40%, likely due to inaccurate activation energy. Both Monkman–Grant (MGR) and modified Monkman–Grant (MMGR) models are applicable. The four QT steels follow the same MMGR model, whereas the TMCP-QT steel follows a different model. However, MGR parameters are influenced by strength grade, temperature, and delivery condition, and corresponding values are provided.</p>

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Creep Behavior and Creep Life of High Strength Structural Steel at Elevated Temperatures

  • 期刊论文

  • 发表日期：

    2025年8月5日

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  • Jun Yan,
  • Chao Zhang

摘要

Creep behaviors of high strength structural steels (HSSSs) may lead to progressive collapse of high-rise buildings that widely use HSSSs as material of load-bearing components in incident fires. However, their high-temperature creep mechanisms and damage modes remain unclear, and predictive models of creep life are lacking. This study analyzes the creep rupture data of Q550, Q690, Q890 and Q960 HSSS (including Q690 in both quenching and tempering (QT) and thermal–mechanical control process (TMCP) followed by quenching and tempering (TMCP-QT)) to investigate their creep mechanisms, fracture modes and prediction of creep life. The results show that the creep mechanism of HSSS below 600 °C is power law breakdown creep, whereas a transition in creep mechanism occurs as the temperature above 600 °C. In QT HSSS, creep damage is dominated by power-law and diffusion creep, necking, and microstructural degradation, leading to cavity growth. In TMCP-QT HSSS, damage is associated with reduced dislocation density, precipitate formation, and subgrain coarsening. The Larson-Miller (LM) and Orr-Sherby-Dorn (OSD) methods predict QT HSSS creep life with with about 20% error. For TMCP-QT, LM has a 20% error, while OSD’s error is around 40%, likely due to inaccurate activation energy. Both Monkman–Grant (MGR) and modified Monkman–Grant (MMGR) models are applicable. The four QT steels follow the same MMGR model, whereas the TMCP-QT steel follows a different model. However, MGR parameters are influenced by strength grade, temperature, and delivery condition, and corresponding values are provided.