基于DIC与EBSD技术的GH4169合金拉伸变形行为实时研究

Real-Time Tracking of Tensile Deformation Behavior in GH4169 Under Tensile Stress Based on DIC and EBSD

摘要:

通过同步介观数字图像相关（DIC）与电子背散射衍射（EBSD）原位表征技术，研究了GH4169高温合金在室温单轴拉伸下的变形行为。结果表明：在晶粒偏转动力学方面，基于自主研发M-DIC软件量化分析发现，在单轴拉伸时，沿拉伸轴水平方向呈双向旋转，在1100 MPa应力水平下，能够得到±0.6°的震荡偏转角，并在应力轴45°方向上萌生出晶界微孔。EBSD晶体学分析揭示了载荷依赖性滑移演变规律：在初始阶段，具有高施密德因子（>0.4）的软取向滑移系被激活，随后在滑移过程中转变为硬取向滑移系，在晶内形成平行滑移带，晶界出现位错塞积。单轴拉伸过程出现应变能累积特征，为双阶段积累模式：初期以晶界局部化为主，随后发展为晶内扩展，最终在大角度晶界处萌生裂纹，其中孪晶界展现出优于大角度晶界的力学稳定性。变形织构特征为铜型织构组分C｛112｝<11>、 S｛123｝<63>和B｛110｝<10>。完整变形链如下：软取向滑移系滑移→位错滑移启动→晶粒旋转主导应变分配→晶间应力集中→晶界开裂主导破坏。本研究揭示的跨尺度变形机制为晶界工程优化镍基高温合金提供了关键理论依据。

Abstract:

The deformation behavior of GH4169 superalloy under room-temperature uniaxial tension was investigated through synchronized mesoscopic digital image correlation (DIC) and electron backscatter diffraction (EBSD) in-situ characterization techniques. Results show that in the field of grain deflection dynamics, through quantitative analysis using the independently developed M-DIC software, during uniaxial tension with significant bidirectional rotation along the tensile axis and the stress level of 1100 MPa, oscillatory rotation of ±0.6° can be obtained, and microvoids are generated at the grain boundaries with 45° to the stress axis. EBSD crystallographic analysis demonstrates the load-dependent slip system evolution: in the initial stage, the soft-oriented systems with high Schmid factor (>0.4) is activated and then transformed into hard-oriented systems during cross-slip, generating parallel slip bands and dislocation pile-ups at grain boundaries. During the uniaxial tensile process, the characteristic of strain energy accumulation is observed, which follows a two-stage accumulation pattern: initial grain boundary localization (Stage I) and intragranular propagation (Stage II). Ultimately, the intergranular cracks are initiated at triple junctions, and the twin boundaries exhibit superior mechanical stability compared with the large-angle grain boundaries. Deformation texture characteristics indicate the copper-type components, including C{112}<11>, S{123}<63>, and B{110}<10>. The complete deformation sequence is as follows: cross-slip of soft-oriented slip systems→initiation of dislocation slip→strain partitioning through grain rotation→intergranular stress concentration→damage dominated by boundary cracking. The cross-scale deformation mechanism revealed in this study provides critical guidance for the crystal boundary engineering to optimize nickel-based superalloys.