P91钢高温蠕变行为表征技术研究
发布时间：2018-10-13 13:08
【摘要】：为了研究服役构件的蠕变损伤行为,本文采用磁性检测法、X射线衍射法以及硬度法等方法来表征P91钢在不同蠕变状态下的损伤情况。首先对P91钢进行高温单轴拉伸试验,得到不同温度下P91钢的高温力学性能。随后,通过给定条件下高温蠕变持久试验,得到了所需的蠕变曲线和试样的断裂时间。根据完整的蠕变曲线,在各蠕变阶段选取间断时间点进行蠕变间断试验,制备不同蠕变状态下的损伤试样。最后利用磁滞回线检测、X射线衍射检测以及硬度检测对蠕变试样的损伤状态进行参数化表征,并结合金相观察以及断口组织观察,进一步验证参数化表征的准确性。具体的研究内容与结论如下:1)高温单轴拉伸试验得到P91钢在620℃和600℃条件下的力学性能,包括抗拉强度σb、屈服强度σ0.2、弹性模量E以及延伸率δ。通过蠕变持久试验获得了 620℃、145 MPa和600℃、175MPa条件下的蠕变曲线和断裂时间,并获得蠕变间断试验的时间,进而通过蠕变间断试验制备损伤试样。2)磁性检测、X射线衍射以及硬度法检测的结果显示:磁性参数矫顽力(Hc)、剩磁(Br)以及最大磁导率(μm)随着蠕变时间的变化趋势,半宽高(FWHM)、位错密度(ρ)随蠕变时间的变化趋势,以及硬度值(HV)随着蠕变时间的变化趋势均呈现先上升后下降的趋势。结合金相以及断口组织观察,结果显示:上述三种检测方法可以较好地表征高温下的蠕变损伤状态。3)通过对上述三种测量结果的全面分析,结果表明:磁性检测方法中磁性参数受材料的化学成分以及结构影响,且测量简单,但在短时蠕变损伤中,表征参数对材料内部组织的演化情况不够敏感;X射线衍射方法较为成熟,但其适用于应力急剧变化且范围较小时,且局限于测量构件表面的损伤状态,并对人体健康具有一定的危害;硬度检测法简单易行,但硬度参量是反映材料内部组织演化以及材料性能的间接参量,一般作为参考指标来使用。综上所述,本文采用的磁性检测法、X射线衍射法以及硬度法均实现了对P91钢不同蠕变状态的参数化表征,且每种方法各有优缺点。其中,磁性检测法能够更直接地反映P91钢在不同蠕变阶段的内部组织演化情况,以便进一步表征P91钢在蠕变过程中材料内部的损伤情况。
[Abstract]:In order to study the creep damage behavior of service members, magnetic detection method, X-ray diffraction method and hardness method are used to characterize the damage of P91 steel under different creep states. First, the high temperature uniaxial tensile test of P91 steel was carried out, and the mechanical properties of P91 steel at different temperatures were obtained. Then, the creep curve and fracture time of the specimen are obtained by the creep rupture test at high temperature under a given condition. According to the complete creep curve, the discontinuous creep test was carried out at different time points in the creep stage, and the damage samples were prepared under different creep states. Finally, the damage state of creep specimens was parameterized by hysteresis loop detection, X-ray diffraction and hardness measurement. The accuracy of parameterized characterization was further verified by metallographic observation and fracture microstructure observation. The specific research contents and conclusions are as follows: 1) the mechanical properties of P91 steel at 620 鈩，
本文编号：2268737
[Abstract]:In order to study the creep damage behavior of service members, magnetic detection method, X-ray diffraction method and hardness method are used to characterize the damage of P91 steel under different creep states. First, the high temperature uniaxial tensile test of P91 steel was carried out, and the mechanical properties of P91 steel at different temperatures were obtained. Then, the creep curve and fracture time of the specimen are obtained by the creep rupture test at high temperature under a given condition. According to the complete creep curve, the discontinuous creep test was carried out at different time points in the creep stage, and the damage samples were prepared under different creep states. Finally, the damage state of creep specimens was parameterized by hysteresis loop detection, X-ray diffraction and hardness measurement. The accuracy of parameterized characterization was further verified by metallographic observation and fracture microstructure observation. The specific research contents and conclusions are as follows: 1) the mechanical properties of P91 steel at 620 鈩，
本文编号：2268737
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