Method for the Detection of Grain Boundaries in α Ti-Based Alloys by means of Polarized Light Microscopy and Image Processing in MATLAB

Morales-Rivas, Lucía; Diederichs, Stella; Böhme, Luisa; Gordo, E.; Hebestreit, A.; Kerscher, Eberhard

doi:10.3139/147.110515

Cited by 7 publications

(3 citation statements)

References 3 publications

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“…In the study of Liu et al, [8] SEM images of AlSi10Mg processed by laser powder bed fusion (PBF-LB/M) were converted into binary images to analyze morphology features of the eutectic, cellular Al-Si microstructure. Morales-Rivas et al [9] used an automated image processing procedure based on the Canny method to detect grain boundaries on polarized LOM images of an α-Ti-based alloy. Another approach [4,10] used a combination of LOM and SEM images to segment and analyze the second phase of dual-phase steels.…”

Section: Doi: 101002/adem202300876mentioning

confidence: 99%

On the Reliability of Automated Analysis of Fracture Surfaces Using a Novel Computer Vision‐Based Tool

Engelhardt,

Decke,

Meier

et al. 2023

Adv Eng Mater

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Fracture surface analysis is of utmost importance with respect to structural integrity of metallic materials. This especially holds true for additive manufactured materials. Despite an increasing trend of automatization of testing methods, the analyzation and classification of fatigue fracture surface images is commonly done manually by experts. Although this leads to correct results in most cases, it has several disadvantages, e.g., the need of a huge knowledge base to interpret images correctly. Therefore, an unsupervised tool analyzing overview images of fatigue fracture surface images was developed supporting inexperienced users to identify the origin of the fracture. The tool was developed using fracture surface images of additive manufactured Ti6Al4V specimens fatigued in the High‐Cycle Fatigue regime and is based on the identification of river marks. Different recording parameters seem to have no significant influence on the tool’s results if pre‐processing settings are adapted. Moreover, it is possible to analyze images of other materials with the tool as long as the fracture surfaces contain river marks. However, special features like multiple origins or origins located in direct vicinity to the surface, e.g., caused by other increased plastic strains, require a further tool development or alternative approaches.This article is protected by copyright. All rights reserved.

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Section: Doi: 101002/adem202300876mentioning

confidence: 99%

On the Reliability of Automated Analysis of Fracture Surfaces Using a Novel Computer Vision‐Based Tool

Engelhardt,

Decke,

Meier

et al. 2023

Adv Eng Mater

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“…After an appropriate virtual rotation of the PLM pictures back to the original position, grain boundaries are detected in each one based on gray contrast. The grain boundaries are used for an automated superimposition of the pictures and the subsequent grain recognition [11]. Subsequently, the gray evolution for each grain is fitted to a sine function, from which the phase shift and the amplitude values are obtained, as explained.…”

Section: Description Of C-axis Orientation Mapping Based On Polarizedmentioning

confidence: 99%

Orientation mapping of cp-Ti by reflected polarized light microscopy

2020

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Deformation and fracture mechanisms, and therefore mechanical behavior, in metals and metallic alloys with hexagonal close packed structures, such as α-Ti, strongly depend on the crystal c-axis orientation of the grains. Taking advantage of the intrinsic optical anisotropy that these structures present, a computer-aided method based on conventional reflected polarized light microscopy has been developed for c-axis orientation mapping. The application of the method on texture-free and textured commercially pure Ti is proposed for the examination of relevant crystallographic features.

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“…1). An ultrafine-grained material state was produced by equal channel angular pressing technique applied to a cp-Ti Grade 4 rectangular bar, so that the average grain size measured according to [9] is less than 2.5 µm. The second material state from a hot-rolled cp-Ti Grade 2 sheet with 0.6 mm thickness shows an average grain size of 35 µm and the largest grains can be observed in the micrograph of a cp-Ti Grade 2 round bar with an average grain size of 100 µm.…”

Section: Materials and Specimensmentioning

confidence: 99%

Forecast of the fatigue crack initiation site of commercially pure Titanium miniature specimens with local surface topography data

et al. 2020

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Surfaces of technical components rarely appear in perfectly smooth condition. During fatigue loading, stress concentrations at surface asperities cause localized plastic deformation that can lead to crack initiation. Therefore, we have established a computer-aided method based on material ratio curves to investigate the possibility to predict the crack initiation site in fatigue tests by using detailed information on the local surface topography. The present study shows the results of investigations on the mutual influence of the average grain size and the surface condition on the fatigue behavior of commercially pure Titanium (cp-Ti) miniature specimens. Three cp-Ti states were investigated: two types of coarse-grained cp-Ti Grade 2 with 35 µm and with 100 µm average grain size and one ultrafine-grained cp-Ti Grade 4 state with less than 2.5 µm average grain size. Confocal microscopy provided the surface topography data of all specimens and data post-processing was applied to the topography in order to locate critical areas where crack initiation may preferentially occur. These areas were compared with the actual crack initiation areas in fatigue test. Finally, scanning electron microscopy (SEM) images of the fracture surfaces were studied to analyze fatigue crack initiation site and crack path of the three microstructural states.

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Method for the Detection of Grain Boundaries in α Ti-Based Alloys by means of Polarized Light Microscopy and Image Processing in MATLAB

Cited by 7 publications

References 3 publications

On the Reliability of Automated Analysis of Fracture Surfaces Using a Novel Computer Vision‐Based Tool

On the Reliability of Automated Analysis of Fracture Surfaces Using a Novel Computer Vision‐Based Tool

Orientation mapping of cp-Ti by reflected polarized light microscopy

Forecast of the fatigue crack initiation site of commercially pure Titanium miniature specimens with local surface topography data

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