GH4169高温合金热处理状态的电磁检测

发布时间：2018-06-13 22:29

本文选题：GH4169 + 热处理组织　；参考：《南昌航空大学》2017年硕士论文

【摘要】：GH4169高温合金广泛应用于航空航天等领域,其微观组织决定了使用性能,通过对组织的分析,可以评判其使用性能是否符合工程实际使用的需求,常规的微观组织检测使用金相或电子显微镜分析,需要对零件进行破坏性试验且不能实现在役检测。本论文研究GH4169合金材料合金组织与涡流、磁导率、电导率间的关系,力图建立材料的涡流信号、电导率、磁导率特征和组织的关系,实现材料材料的组织无损检测和评价。本文通过改变GH4169合金固溶温度、冷却方式形成不同的微观组织,用差热分析确定其相变点和强化相的溶解温度,用金相法、电镜观察其组织变化,用ImageJ开放平台自编金相分析软件提取金相组织的特征参数(平均晶粒直径、晶粒长轴、晶粒短轴等),并测量不同组织状态下的材料硬度,随后对不同金相组织、残余应力的试样进行涡流电导率测量、在固定磁场强度条件的的表面磁感应强度测量、和涡流提离点差幅值测量。金相分析结果表明,在GH4169合金相变温度以下固溶处理,因为δ相的存在,在晶间起到钉扎作用,所以晶粒平均直径(26~28μm)、长轴(30~36μm)和短轴尺寸(20~22μm)增长并不明显,在相变点以上固溶处理时,晶粒直径增长速度明显增大(50~123μm)。涡流电导率测量表明相变点以下的电导率高于相变点以上电导率,电导率随固溶温度升高而下降,垂直于表面磁感应强度随固溶温度升高而升高,涡流提离点差幅值随固溶温度升高减小,这些变化均对应固溶过程中强化相的溶解,固溶原子融入基体,晶格畸变增加,导致电导率下降、涡流提离点差幅值减小、强化相对磁畴的钉扎作用降低,相对磁导率上升。随着合金热处理状态的改变,金相组织随之发生变化,材料电磁特性亦发生改变。本论文的研究结果可以用于无损检测GH4169的组织变化,用于航空发动机中高温长期使用的GH4169组织演变关系研究,保证航空发动机的使用安全。
[Abstract]:GH4169 superalloy is widely used in aerospace and other fields. Its microstructure determines its performance. By analyzing the microstructure, it can be judged whether the performance of GH4169 meets the requirements of engineering practice. Metallography or electron microscope is used in the conventional microstructure testing. It is necessary to carry out destructive tests on the parts and it is not possible to carry out in-service inspection. In this paper, the relationship between the microstructure of GH4169 alloy and eddy current, permeability and conductivity is studied. The relationship between eddy current signal, conductivity, permeability and microstructure is established to realize the nondestructive testing and evaluation of the microstructure of GH4169 alloy. In this paper, by changing the solution temperature of GH4169 alloy, different microstructures are formed in the cooling mode. The phase transition point and the solution temperature of the strengthened phase are determined by differential thermal analysis. The microstructure changes are observed by metallographic method and electron microscope. The characteristic parameters of metallographic structure (average grain diameter, grain long axis, grain short axis, etc.) were extracted by ImageJ open platform, and the hardness of the materials was measured under different microstructure states. The residual stress samples were measured by eddy current conductivity measurement, surface magnetic induction intensity measurement under fixed magnetic field intensity condition, and eddy current lift point difference amplitude measurement. The results of metallographic analysis show that under the transformation temperature of GH4169, the average diameter of grain is 2628 渭 m / m, the long axis is 30 ~ 36 渭 m) and the short axis size is 2022 渭 m) due to the existence of 未 phase. The growth rate of grain diameter increases obviously when the solution treatment is above the transformation point. The eddy current conductivity measurement shows that the conductivity below the transition point is higher than that above the phase transition point, and the conductivity decreases with the increase of the solution temperature, and the magnetic induction intensity increases with the increase of the solution temperature. The amplitude of eddy current lift point difference decreases with the increase of solution temperature. These changes correspond to the dissolution of strengthening phase, the incorporation of solid solution atoms into the matrix, the increase of lattice distortion, the decrease of conductivity and the decrease of eddy current lift point difference amplitude. The pinning effect of the strengthened relative domain decreases and the relative permeability increases. With the change of the heat treatment state of the alloy, the microstructure of the alloy changes and the electromagnetic properties of the alloy change. The results of this paper can be used for nondestructive detection of the microstructure of GH4169, and for the study of the relationship between the microstructure evolution of GH4169, which has been used for a long period of time in aero-engines, to ensure the safety of the use of aeroengines.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG156;TG132.3

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