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Inversion methodology for ultrasonic characterization of polycrystals with clusters of preferentially oriented grains
Ultrasonics ( IF 4.2 ) Pub Date : 2021-05-15 , DOI: 10.1016/j.ultras.2021.106433
S.I. Rokhlin , G. Sha , J. Li , A.L. Pilchak

Titanium alloys are widely used in the aerospace industry. However, due to presence of microtexture, which is characterized by preferred crystallographic orientation clustering of thousands of alpha crystallites, cold dwell fatigue may significantly reduce the part life. To satisfy the practical need for nondestructive microtexture characterization, an inverse ultrasonic methodology is proposed to quantify mean parameters of microtexture regions (MTRs) having ellipsoidal shapes. One limitation of previous model-based ultrasonic inversion methods is required knowledge of elastic constants of the crystallites, which are rarely available for engineering alloys. This study overcomes this constraint by adopting the far field attenuation model, JASA, 137 (5), 2655–2669 (2015), and the backscattering model for ultrasonic wave interaction with microtexture. In the methodology developed, all necessary averaged MTR characteristics are obtained solely from directional ultrasonic measurements (backscattering, attenuation, and velocity) without a prior knowledge of material microstructures or elastic properties of different material phases. The inversion method is illustrated by simulations. To support the inversion methodology, the mean MTR sizes, morphology, and elastic scattering factors are determined from the ultrasonic experiment on a Ti-6242 alloy sample. The inversion results are compared with destructive electron backscatter diffraction (EBSD) analysis from which the MTRs are segmented using a non-contiguous grouping criteria. Good agreement is found.



中文翻译:

具有优先取向晶粒簇的多晶超声表征的反演方法

钛合金广泛用于航空航天工业。但是,由于存在微观纹理(其特征是成千上万个alpha晶粒具有较好的晶体学取向簇聚特征),因此,冷驻留疲劳可能会大大缩短零件寿命。为了满足对非破坏性微观纹理表征的实际需求,提出了一种反向超声方法来量化具有椭圆形形状的微观纹理区域(MTR)的平均参数。以前基于模型的超声反演方法的局限性是需要了解微晶的弹性常数,而这种合金很少用于工程合金。本研究通过采用远场衰减模型JASA 137克服了这一限制。(5),2655-2669(2015),以及超声波与微纹理相互作用的反向散射模型。在开发的方法中,所有必需的平均MTR特性仅从定向超声测量(反向散射,衰减和速度)获得,而无需事先了解不同材料相的材料微观结构或弹性特性。通过仿真说明了反演方法。为了支持反演方法,根据对Ti-6242合金样品进行的超声实验确定了平均MTR尺寸,形态和弹性散射因子。将该反演结果与破坏性电子背散射衍射(EBSD)分析进行了比较,该分析使用非连续分组标准对MTR进行了分段。找到良好的协议。

更新日期:2021-05-24
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