Morphology, Microstructure, and Mechanical Properties of S32101 Duplex Stainless-Steel Joints in K-TIG Welding
Abstract
:1. Introduction
2. Materials and Methods
2.1. Material and Welding Procedure
2.2. Keyhole Image Acquisition and Feature Extraction
- (1)
- Combining the characteristics of the grayscale distribution of the keyhole grayscale image, use 5 × 5 disc-shaped structural elements for the corrosion operation;
- (2)
- The method of multi-level threshold segmentation was used to solve the binary image of the keyhole, and the edge points were obtained by line scanning. The specific threshold segmentation was realized by Formulas (1) and (2). f (x, y), h (x, y) and g (x, y) were the gray values at the coordinates (x, y) of the raw image and the image after two divisions. T1 = 240, and T2 is the threshold calculated by the Otsu algorithm for h (x, y). Finally, the ellipse is fitted based on the least square method, as shown in Figure 3c.
2.3. Joint Characterization
3. Results and Discussion
3.1. Geometry Profile of K-TIG Weld of S32101 Duplex Stainless Steel
3.2. Dynamic Behavior and Characteristic Parameters of the Keyhole
3.2.1. Dynamic Behavior of the Keyhole
3.2.2. Characteristic Parameters of the Keyhole
3.3. Impact Property
3.4. Effect of Microstructure in the WMZ on Its Impact Toughness
3.4.1. The Volume Fraction and Morphology of Austenite
3.4.2. Effect of CSLGB on Impact Toughness of Welded Joint
3.4.3. Effect of Random Phase Boundary on Impact Toughness of Welded Joint
4. Conclusions
- The S32101 DSS welded joints were produced by applying a K-TIG welding system under different WS. When the WS were 3.5 mm/s and 4.0 mm/s, the weld morphologies were better.
- The keyhole was oval, and the characteristic parameters of the keyhole were dynamically changed during K-TIG welding. When the WS decreased, XA, YA, and SA of the keyhole changed significantly, which proved that the characteristic parameters of the keyhole can indirectly indicate the forming quality of the weld.
- When the WS was 3.5 mm/s, the impact toughness of the WMZ was better. The microstructure, GB orientation characteristics, and phase boundary have a certain influence on the impact toughness of the WMZ. When the proportion of the austenite, Σ3 CSLGB and random phase boundary increased, the impact toughness of the WMZ also increased.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
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Test | Welding Current | Welding Speed | Flow Rate of Argon |
---|---|---|---|
(A) | (mm/s) | L/min | |
1 | 530 | 5.0 | 20 |
2 | 530 | 4.5 | 20 |
3 | 530 | 4.0 | 20 |
4 | 530 | 3.5 | 20 |
5 | 530 | 3.0 | 20 |
Welding Speed (mm/s) | Keyhole Image |
---|---|
5.0 | |
4.5 | |
4.0 | |
3.5 | |
3.0 |
Keyhole Parameters | Welding Speed (mm/s) | Rate of Change (4.0 mm/s → 3.0 mm/s, %) | ||
---|---|---|---|---|
4.0 | 3.5 | 3.0 | ||
YA (mm) | 1.21 | 1.32 | 1.78 | 47.1 |
XA (mm) | 1.42 | 1.62 | 2.20 | 54.9 |
SA (mm2) | 1.33 | 1.64 | 3.19 | 139.8 |
XA/YA | 1.16 | 1.17 | 1.23 | 6.0 |
Welding Speed (mm/s) | Absorbed Energy, Akv (J) (20 °C) | ||||
---|---|---|---|---|---|
1 | 2 | 3 | Mean Value | ||
WM | 4.0 | 148 | 146 | 133 | 142 |
3.5 | 166 | 172 | 179 | 172 | |
BM | / | 205 | 215 | 208 | 209 |
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Cui, S.; Yu, Y.; Tian, F.; Pang, S. Morphology, Microstructure, and Mechanical Properties of S32101 Duplex Stainless-Steel Joints in K-TIG Welding. Materials 2022, 15, 5432. https://doi.org/10.3390/ma15155432
Cui S, Yu Y, Tian F, Pang S. Morphology, Microstructure, and Mechanical Properties of S32101 Duplex Stainless-Steel Joints in K-TIG Welding. Materials. 2022; 15(15):5432. https://doi.org/10.3390/ma15155432
Chicago/Turabian StyleCui, Shuwan, Yunhe Yu, Fuyuan Tian, and Shuwen Pang. 2022. "Morphology, Microstructure, and Mechanical Properties of S32101 Duplex Stainless-Steel Joints in K-TIG Welding" Materials 15, no. 15: 5432. https://doi.org/10.3390/ma15155432