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    X80M管线钢的热变形行为及应变补偿型本构模型

    Thermal Deformation Behavior and Strain Compensation Constitutive Model of X80M Pipeline Steel

    • 摘要: 采用Gleeble-3800型热力模拟试验机对X80M管线钢进行单道次热压缩试验,研究了其在变形温度900~1 100 ℃和应变速率0.1~7 s−1条件下的热变形行为;根据试验得到的真应力-真应变曲线,考虑真应变对流变应力的影响构建了X80M管线钢的应变补偿型Arrhenius本构模型,并对该模型进行了验证。结果表明:随着变形温度的升高或应变速率的降低,X80M管线钢的流变应力降低,X80M管线钢具有负温度敏感性和正应变速率敏感性;在高变形温度(1 050~1 100 ℃)和低应变速率(0.1~1 s−1)下X80M管线钢表现出动态再结晶特征,在低变形温度(900~1 000 ℃)和高应变速率(4~7 s−1)下则表现出动态回复特征。用构建的应变补偿型本构模型计算的真应力与试验结果相吻合,线性相关系数为0.997,平均相对误差为1.791%;该模型具有较高的预测精度,能够准确预测X80M管线钢的高温流变行为。

       

      Abstract: Single-pass thermal compression tests of X80M pipeline steel were carried out by Gleeble-3800 thermal simulator. The thermal deformation behavior under conditions of deformation temperature ranging from 900 ℃ to 1 100 ℃ and strain rate ranging from 0.1 s−1 to 7 s−1 was studied. According to the true stress-strain curves obtained by tests, the strain compensation Arrhenius constitutive model of X80M pipeline steel was constructed considering the effect of the true strain on the flow stress, and the model was verified. The results show that with the increase of deformation temperature or the decrease of strain rate, the flow stress of X80M pipeline steel decreased; the X80M pipeline steel had negative temperature sensitivity and positive strain rate sensitivity. Under high deformation temperatures (1 050–1 100 ℃) and low strain rates (0.1–1 s−1), X80M pipeline steel exhibited dynamic recrystallization characteristics. Under low deformation temperatures (900–1 000 ℃) and high strain rates (4–7 s−1), it showed dynamic recovery characteristics. The true stress calculated by the constructed strain compensation constitutive model was consistent with the test results. The linear correlation coefficient was 0.997 and the average relative error was 1.791%, indicating that this model had a high prediction accuracy and could accurately predict the high-temperature rheological behavior of X80M pipeline steel.

       

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