Incoloy 825镍基高温合金低周疲劳行为研究

发布时间：2018-06-10 00:15

本文选题：Incoloy + 825镍基高温合金　；参考：《沈阳工业大学》2017年硕士论文

【摘要】：镍基高温合金具有优异的抗高温疲劳性能、抗氧化性能以及耐应力腐蚀性能,故广泛应用于机械装备、航空航天、石油化工等领域,并被用于制作工业用燃气轮机叶片等承受严苛工作条件的关键工程构件。疲劳是镍基高温合金工程构件的主要失效形式之一。基于此,本文通过在室温、650℃和760℃下进行外加总应变幅控制的低周疲劳实验,对Incoloy 825镍基高温合金基体及其焊接接头的低周疲劳行为进行了研究,确定了合金的循环应力响应行为、低周疲劳寿命行为和循环应力-应变行为,并且确定出不同温度下的应变疲劳参数,同时利用透射电子显微镜(TEM)和扫描电子显微镜(SEM)对疲劳变形后的位错亚结构和低周疲劳断口形貌进行了分析,以期为Incoloy 825镍基高温合金工程构件的抗疲劳设计提供可靠的理论依据。低周疲劳实验结果表明:室温下,Incoloy 825镍基高温合金基体在低周疲劳变形初期呈现出循环应变硬化,而在低周疲劳变形后期则呈现出循环应变软化;650℃下,Incoloy 825镍基高温合金基体在低周疲劳变形初期呈现出循环应变硬化,而在低周疲劳变形后期则呈现出循环稳定或者循环应变硬化;760℃下,Incoloy 825镍基高温合金基体在低周疲劳变形初期呈现出循环应变硬化,而在低周疲劳变形后期则呈现出循环应变软化或者循环稳定。室温下,Incoloy 825镍基高温合金焊接接头在低周疲劳变形初期呈现出循环稳定、循环应变硬化或者循环应变软化,而在低周疲劳变形后期则呈现出循环应变软化;760℃下,Incoloy 825镍基高温合金焊接接头在低周疲劳变形初期呈现出循环应变硬化,而在低周疲劳变形后期则呈现出循环应变软化。当外加总应变幅相同时,Incoloy 825镍基高温合金基体在室温下呈现出最长的低周疲劳寿命,在760?C下则呈现出最短的低周疲劳寿命,而Incoloy 825镍基高温合金焊接接头在室温下的低周疲劳寿命较其在760℃下的低周疲劳寿命更长。在相同温度下,Incoloy 825镍基高温合金基体的低周疲劳寿命均长于Incoloy 825镍基高温合金焊接接头的低周疲劳寿命。在不同温度下,Incoloy 825镍基高温合金基体及其焊接接头的塑性应变幅、弹性应变幅与断裂时的载荷反向周次之间均分别呈现出单斜率线性关系,并分别服从Coffin-Manson公式和Basquin公式。此外,在不同实验温度下,Incoloy 825镍基高温合金基体及其焊接接头的循环应力-应变曲线均呈现出单斜率线性行为。利用透射电子显微镜对Incoloy 825镍基高温合金在不同温度和外加总应变幅下低周疲劳变形后的位错亚结构进行的观察与分析结果表明,其主要疲劳变形机制为平面滑移。低周疲劳变形时,合金中可形成亚晶、位错阵列及胞状亚结构,并可观察到位错塞积群以及平行分布的位错墙与滑移带。利用扫描电子显微镜对Incoloy 825镍基高温合金在不同条件下的低周疲劳断口形貌进行的观察与分析结果表明,合金的疲劳裂纹均以穿晶方式萌生与扩展。
[Abstract]:Nickel base superalloy has excellent resistance to high temperature fatigue, antioxidation and stress corrosion resistance, so it should be widely used in mechanical equipment, aerospace, petrochemical and other fields, and is used to make industrial gas turbine blades and other key engineering components to withstand harsh working conditions. Fatigue is a nickel base superalloy engineering component Based on this, the low cycle fatigue behavior of the Incoloy 825 nickel base superalloy matrix and its welded joint was studied by the low cycle fatigue test at room temperature, 650 and 760 C. The cyclic stress response behavior, low cycle fatigue life behavior and cycle of the alloy were determined. Stress strain behavior and strain fatigue parameters at different temperatures are determined, and transmission electron microscope (TEM) and scanning electron microscope (SEM) are used to analyze the dislocation substructure and low cycle fatigue fracture morphology after fatigue deformation, in order to provide reliability for the fatigue design of Incoloy 825 nickel base superalloy engineering components. The results of low cycle fatigue test show that at room temperature, the matrix of Incoloy 825 nickel base superalloy presents cyclic strain hardening at the early stage of low cycle fatigue deformation, while the cyclic strain softens in the late stage of low cycle fatigue deformation. At 650, the Incoloy 825 nickel base high temperature gold alloy matrix presents a cyclic strain at the early stage of low cycle fatigue deformation. At 760 centigrade, the matrix of Incoloy 825 nickel base superalloy presents a cyclic strain hardening at the early stage of low cycle fatigue deformation, while at the late stage of low fatigue deformation, the cyclic strain is softened or circulated. At room temperature, the Incoloy 825 nickel base is high. In the early stage of low cycle fatigue deformation, the welded joints of the warm alloy welded joints showed a cyclic stability, the cyclic strain hardening or the cyclic strain softened, while the cyclic strain softened in the late period of low cycle fatigue deformation. At 760, the Incoloy 825 nickel base superalloy welded joint showed a cyclic strain hardening at the early stage of low cycle fatigue deformation, and at the low cycle fatigue fatigue. At the same time, the Incoloy 825 nickel base superalloy matrix exhibits the longest low cycle fatigue life at room temperature and the shortest low cycle fatigue life at 760? C, while the low cycle fatigue life of the Incoloy 825 nickel base superalloy welded joint at room temperature is 760. At the same temperature, the low cycle fatigue life of the Incoloy 825 nickel base superalloy substrate is longer than that of the Incoloy 825 nickel base superalloy welded joint at the same temperature. At different temperatures, the plastic strain amplitude, elastic strain amplitude and fracture time of the Incoloy 825 nickel base superalloy matrix and its welding joint are made at different temperatures. The linear relationship between the load reverse cycles and the Coffin-Manson formula and the Basquin formula are presented respectively. At different experimental temperatures, the cyclic stress strain curves of the Incoloy 825 nickel base superalloy matrix and its welded joint show the linear behavior of the monoclinic rate. The transmission electron microscope is used for the Inco. The observation and analysis of dislocation substructures of loy 825 nickel base superalloy at low cycle fatigue and deformation at different temperatures and additional amplitudes show that the main mechanism of the fatigue deformation is plane slip. In the low cycle fatigue deformation, subgrains, dislocation arrays and cell substructures can be formed in the alloy, and the wrong plug group can be observed. The dislocation walls and slip zones of parallel distribution are observed and analyzed by scanning electron microscopy (SEM) for low cycle fatigue fracture morphology of Incoloy 825 nickel base superalloy under different conditions. The results show that the fatigue cracks in the alloy are all sprout and expanding in the mode of transgranular.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG132.3

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