液化天然气储罐内罐焊接结构疲劳寿命

Fatigue life of welded structure of inner tank in liquefied natural gas storage tank

  • 摘要:
    目的 该研究旨在比较TIP-TIG (TT)与埋弧焊(Submerged arc welding, SAW)在低温条件下的低周疲劳性能,并建立适用于液化天然气(Liquefied natural gas, LNG)工况的寿命预测模型。
    方法 采用9Ni钢TT与SAW焊接接头在室温和−120 ℃下进行应变控制疲劳试验,根据试验数据拟合了Manson-Coffin,Morrow与SWT等寿命模型。
    结果 结果表明,低温导致两类接头的循环应力幅升高,而TT接头表现出更稳定的循环行为和显著更长的疲劳寿命,其优势来源于细化的焊缝组织和较低的缺陷敏感性。在寿命模型中,SWT在低温下预测精度最高。
    结论 TT更适用于LNG低温服役环境,建立的应变寿命模型可为关键焊接部位的寿命评估和工艺优化提供参考。

     

    Abstract: Objective This study aims to compare low-temperature low cycle fatigue performance of TIP-TIG (TT) and submerged arc welding (SAW) joints, and to establish a fatigue life prediction model suitable for liquefied natural gas (LNG) service conditions. Methods Low cycle fatigue tests were performed on TT and SAW joints of 9Ni steel under strain control at room temperature and −120 ℃. Based on the experimental data, fatigue life models such as Manson-Coffin, Morrow and SWT were fitted. Results The results show that low temperature increases cyclic stress amplitude of both types of welded joints, while TT joints exhibit more stable cyclic behavior and a significantly longer fatigue life, mainly due to its refined weld microstructure and lower defect sensitivity. Among the evaluated models, SWT model provides the highest prediction accuracy at low temperature. Conclusion TT is more suitable for low temperature service conditions of LNG applications, and the established strain life models can provide useful reference for fatigue life evaluation and welding process optimization of critical welded components.

     

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