基于非线性超声纵波的汽轮机耐热材料蠕变损伤检测与评价研究

发布时间：2018-05-14 00:05

本文选题：非线性超声 + 汽轮机耐热材料　；参考：《华东理工大学》2015年硕士论文

【摘要】：超超临界汽轮机高温部件长期服役会产生蠕变损伤,对设备的安全运行存在潜在的威胁,快速、有效地检出高温构件蠕变损伤状况对保证设备服役安全意义重大。最近研究表明,材料损伤程度与超声波非线性效应有紧密的联受,受到学者们的广泛关注。本文利用实验室模拟获得汽轮机螺栓、转子试样的不同蠕变损伤水平,进行了非线性超声纵波表征耐热材料蠕变损伤状态的实验研究,主要研究内容和结果如下：(1)汽轮机镍基高温螺栓材料In783蠕变损伤状态的非线性超声纵波表征实验研究。以包含不同蠕变损伤水平的高温镍基螺栓材料In783为对象,进行蠕变损伤水平的非线性超声纵波表征实验,完成了不同损伤试样的微观组织和机理分析。结果发现：超声纵波非线性参量随蠕变变形的增大而单调增加,显微硬度随蠕变应变的变化与超声非线性变化趋势一致,表明超声纵波非线性参量与材料力学性能退化存在函数关联。超声非线性参量的增大主要源于材料内部位错密度的增加及析出相长大。基于位错-析出相模型预测得到了与实验测量值较一致的结果,表明位错-析出相模型可较好描述镍基高温合金与超声非线性参量的关系。(2)汽轮机转子铁素体耐热钢FB2蠕变损伤状态的非线性超声纵波表征实验研究。进行了包含不同蠕变损伤水平的铁素体钢FB2的非线性超声纵波表征实验,完成了不同损伤试样的微观组织和机理分析。结果发现：超声纵波非线性参量随汽轮机转子钢蠕变变形的增大而单调增加,且超声非线性参量变化与蠕变损伤机制存在函数关系。进一步,以位错密度为中间量,建立了稳态蠕变变形速率与超声非线性参量的函数关系。
[Abstract]:The long-term service of the ultra-supercritical steam turbine high temperature components will cause creep damage, which has a potential threat to the safe operation of the equipment. It is of great significance to detect the creep damage condition of the high temperature components quickly and effectively to ensure the safety of the equipment service. Recent studies have shown that the damage degree of materials is closely related to the nonlinear effect of ultrasonic wave, which has attracted extensive attention of scholars. In this paper, different creep damage levels of turbine bolts and rotor specimens are obtained by laboratory simulation, and the experimental study of nonlinear ultrasonic longitudinal wave characterizing creep damage state of heat-resistant materials is carried out. The main contents and results are as follows: (1) the experimental study of nonlinear ultrasonic longitudinal wave characterization of In783 creep damage of nickel based high temperature bolt material for steam turbine. The nonlinear ultrasonic longitudinal wave characterizing the creep damage level of high temperature nickel-base bolt material In783 with different creep damage levels was carried out. The microstructure and mechanism of different damage samples were analyzed. The results show that the nonlinear parameters of ultrasonic longitudinal wave increase monotonously with the increase of creep deformation, and the variation of microhardness with creep strain is consistent with that of ultrasonic nonlinearity. It is shown that there is a functional correlation between the nonlinear parameters of ultrasonic longitudinal wave and the degradation of mechanical properties of materials. The increase of ultrasonic nonlinear parameters is mainly due to the increase of dislocation density and the growth of precipitated phase. Based on the dislocation-precipitation model, the predicted results are in good agreement with the experimental results. It is shown that the dislocation precipitation phase model can better describe the relationship between nickel base superalloy and ultrasonic nonlinear parameters. The experimental study of nonlinear ultrasonic longitudinal wave characterization of FB2 creep damage state of ferrite heat-resistant steel in steam turbine rotor is presented. The nonlinear ultrasonic longitudinal wave characterization experiments of ferrite steel FB2 with different creep damage levels were carried out. The microstructure and mechanism of different damage samples were analyzed. The results show that the ultrasonic longitudinal wave nonlinear parameters increase monotonously with the increase of creep deformation of turbine rotor steel, and there is a functional relationship between the variation of ultrasonic nonlinear parameters and the creep damage mechanism. Furthermore, the functional relationship between steady state creep deformation rate and ultrasonic nonlinear parameters is established with dislocation density as the intermediate value.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34

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