DOI: 10.5061/dryad.9cnp5hqpf
title: Internal defect database of mechanically deformed ferritic steel via X-ray computed tomography

description: Steel is widely utilized as a structural material due to its favorable
 mechanical properties, cost-effectiveness, and reliability, and it is
 expected to remain critical in engineering applications. The properties
 and durability of steel are significantly influenced by internal defects
 formed during mechanical deformation. Quantitative analysis of the
 formation and evolution of these defects is essential for developing
 materials that are both sustainable and tailored to specific applications.
 However, acquiring statistically meaningful datasets of internal defects
 is complex, time-consuming, and costly, resulting in a scarcity of
 comprehensive studies. In this study, we present two comprehensive
 datasets obtained from mechanically deformed ferritic steel samples using
 X-ray computed tomography (X-CT): (1) tensile deformation and (2) fatigue
 deformation. The database includes detailed quantitative descriptions of
 938 defect features from 135 tensile-tested samples and 2,305 defect
 features from 152 fatigue-tested samples. Each dataset comprises
 high-resolution X-CT images and quantified internal defect metrics,
 facilitating detailed statistical analysis.
description: <strong>Tensile testing</strong>
 The tests were conducted at room temperature with a strain rate
 of 10-3 s-1, and local strains of the specimens were measured using a
 digital image correlation (DIC) instrument. X-CT scanning was performed
 using a ZEISS Xradia 520 Versa with the following conditions: 160 kV
 output voltage, 10 W power, and 3 μm step size. Internal topology data of
 deformed specimens were obtained by scanning areas of 3×3×33 mm3 located 3
 mm away from the fracture surface of fractured specimens. The acquired
 data was divided into 3-5 regions.
 <strong>Fatigue testing</strong>
 The tests were conducted with an r-ratio of 0.1 and a maximum
 stress amplitude range of 630-680 MPa. X-CT scanning was performed on a
 3×x3×x3 mm3 area at the center of the gauge of the specimen after
 interrupting the test at a specific cycle. The same conditions were used
 as in the tensile case, except for the measurement area. After that, an
 additional fatigue test was conducted, and X-CT scanning was performed
 again. This process was repeated until the specimen was
 destroyed. <strong>TDA
 analysis</strong> Persistent homology (PH)
 processing was used to provide information about defect density, defect
 size, and homogeneity of defects.
description: # Internal defect database of mechanically deformed ferritic steel via
 X-ray computed tomography This dataset provides high-resolution X-ray
 computed tomography (X-CT) images obtained from tensile and fatigue tests,
 along with internal defect information extracted through Persistent
 Homology analysis. The dataset consists of the following components: *
 `Tensile` folder * `Fatigue` folder * `All_in_one_table.xlsx` (summary
 table of all defect information) --- ## Data Structure Each folder is
 organized and uploaded according to the `Sample Number` in
 `All_in_one_table.xlsx`, and each sample contains subfolders with data
 corresponding to the IDs. For example, `Fatigue_1.zip` includes the data
 for IDs 1, 2, 3, and 4, which correspond to Sample Number 1 of Fatigue
 sheet in `All_in_one_table.xlsx`. The following example illustrates the
 structure of a `Sample Number` folder and its subfolders. ``` Fatigue_1/
 └── ID_1/ ├── 3d/ # 3D visualization data ├── raw/ # Original X-CT images
 ├── window_leveling/ # Processed X-CT images ├── Birth Histogram.jpg #
 Histograms of defect sizes └── Lifetime Histogram.jpg # Histograms of
 inter-defect distances ``` --- ## All-in-one Excel Table The All-in-one
 Excel file contains two sheets: **Tensile** and **Fatigue**, each
 providing detailed defect-related and experimental data extracted from
 X-CT images using Persistent Homology. ### Tensile Sheet This sheet
 summarizes **local strain** and **internal defect characteristics** from
 tensile testing. Each row corresponds to a specific part of a specimen. *
 **Sample number / ID / Parts**: Sample-level identifiers * **Local
 strain**: Measured via Digital Image Correlation (DIC) * **Defect size and
 density**: Number of voids per mm³ in the following ranges: * 0–3 (/mm³) *
 3–6 (/mm³) * \&gt; 6 (/mm³) * **Void distribution**: * D – Average
 inter-defect distance (μm) * V – Standard deviation or spread of defect
 distances ### Fatigue Sheet This sheet contains **interrupted fatigue
 testing** results, allowing analysis of fracture progression and
 crack-related characteristics. * **Sample ID / Stress (MPa)**: Basic test
 settings * **Interrupted point (cycles)**: Cycle count where test was
 paused * **Fractured point (cycles)**: Total cycles until failure *
 **Fracture progress (%)**: Progression toward final fracture * **Crack
 information**: * Presence (Yes/No) * Count / Density / Shape * Thickness
 (mm) / Depth (mm) / Volume (mm³) (when available) * T-grade (Thickness
 grade): Classification of crack thickness * 0–0.15 mm → Grade 1 *
 0.15–0.30 mm → Grade 2 * 0.30–0.45 mm → Grade 3 * D-grade (Depth grade):
 Classification of crack depth * 0–0.30 mm → Grade 1 * 0.30–0.60 mm → Grade
 2 * 0.60–0.90 mm → Grade 3 * **Void density**: Voids per mm³ in: * 0–12
 (/mm³) * 12–24 (/mm³) * **Defect distribution**: * Average inter-defect
 distance (μm) * Heterogeneity (μm) – variation in spacing --- ##
 Experimental Overview * **Tensile Data**\ Collected after tensile testing
 using **Digital Image Correlation (DIC)** equipment, providing localized
 strain measurements. * **Fatigue Data**\ Collected after **interrupted
 fatigue tests**, allowing multiple stages of crack propagation to be
 captured within a specimen.