Microstructure and Thermal Mechanical Behavior of Arc-Welded Aluminum Alloy 6061-T6
<p>Location of thermocouples installed on the plate (TC1 to TC8).</p> "> Figure 2
<p>Conical Gaussian volumetric heat source model.</p> "> Figure 3
<p>Mesh used for numerical simulations using Sysweld: (<b>a</b>) application of the heat source, (<b>b</b>) irregular mesh.</p> "> Figure 4
<p>MFT specimen: (<b>a</b>) machined samples, (<b>b</b>,<b>c</b>) extracted micro-tensile specimen (dimensions in mm), and (<b>d</b>) regions of interest extracted from the welded sample used for DIC.</p> "> Figure 4 Cont.
<p>MFT specimen: (<b>a</b>) machined samples, (<b>b</b>,<b>c</b>) extracted micro-tensile specimen (dimensions in mm), and (<b>d</b>) regions of interest extracted from the welded sample used for DIC.</p> "> Figure 5
<p>Melting zone experimental results compared with FEA.</p> "> Figure 6
<p>Thermal profile: (<b>a</b>) comparison between experiments and finite element simulation at points at different distances from the welding center line; (<b>b</b>) peak temperature comparison.</p> "> Figure 7
<p>Base metal of AA6061-T6: (<b>a</b>) coarse second phase particles distributed randomly; (<b>b</b>) grain size of base metal.</p> "> Figure 8
<p>Light optical micrographs of microstructure of FZ and HAZ: (<b>a</b>) grains in FZ; (<b>b</b>) interface between the HAZ and fusion zone FZ.</p> "> Figure 9
<p>Light optical micrographs of recrystallization and grain growth: (<b>a</b>) zone adjacent to FZ; (<b>b</b>) gradual change in grain size in the zone beneath the FZ.</p> "> Figure 10
<p>Correlation between thermal cycle and microhardness values in HAZ.</p> "> Figure 11
<p>Global response (stress–strain) curves for welded sample and parent metal.</p> "> Figure 12
<p>Illustration of the distribution of local in-plane strain acquired using DIC equivalent to different strains (corresponding to 24 mm specimen gauge length) for two specimens.</p> "> Figure 13
<p>Average value of ԑ<sub>XX</sub> and ԑ<sub>YY</sub> in transverse weld direction for three stress/strain stages: (<b>a</b>) 126 MPa_0.5%; (<b>b</b>) 202 MPa_2.4%; and (<b>c</b>) 225 MPa_5.1%, illustrating local in-plane strain localization.</p> "> Figure 14
<p>Different locations studied on the welded sample.</p> "> Figure 15
<p>Stress-local strain in different locations obtained by DIC for welded sample.</p> "> Figure 16
<p>Average stress–strain behavior (DIC measurements) for welded joint and fracture planes in HAZ (PZ1 and PZ2) compared to base metal thermal cycle distribution across gauge length of DIC test specimen.</p> "> Figure 17
<p>Historical temperature distribution (°C) of extracted samples for DIC tests.</p> "> Figure 18
<p>Correlations between mechanical properties and peak temperature profile along FZ and HAZ (Test-1 and Test-2).</p> ">
Abstract
:1. Introduction
2. Materials and Methods
2.1. Material Used and Welding Procedure
2.2. Numerical Procedure
2.3. Samples’ Preparation for Microstructure Characterization
2.4. Microhardness Measurement
2.5. Micro-Flat-Tensile Tests with Digital Imaging Correlation
3. Results and Discussions
3.1. Thermal Profile and Melting Zone
3.2. Microstructure
3.3. Microhardness across the HAZ
3.4. Micro-Flat-Tensile Tests Using DIC
3.4.1. Local Behavior of HAZ Subzones in Welded Plate Obtained by DIC
3.4.2. Local Stress–Strain Properties Obtained Using DIC test
3.4.3. Thermal Profile and Mechanical Behavior
4. Conclusions
- A thermal finite element analysis produced reasonably accurate results compared to the experimental thermal profile, and the most significant difference between the experimental results and the model results was an 8.3% difference in the temperature measured by the thermocouples nearest to the FZ.
- The mechanical response of the welded sample was significantly influenced by the welding thermal cycle, and thermal cycle variations created different subzones in the HAZ. The over-aged subzone that produced the lowest hardness could be described as a 2.2 mm width plane located 5.9 mm to 8.1 mm on both sides of the welding center line. The symmetrical mechanical response on both sides of the weld was a result of the steady welding speed and robotic welding heat input.
- The HAZ subzones present different plastic properties from zone to zone, and the local mechanical behavior of these zones varies according to the peak temperature to which they are exposed. The mechanical response of the heterogeneous HAZ led to the development of an extreme localization of deformed zones within which necking and fracture occurred during tensile testing. These subzones were closely correlated with the peak temperature.
- Micro-flat tensile tests using the DIC technique together with thermal numerical simulations provided a very interesting and powerful tool to understand the local mechanical behavior of the welded part. It revealed that welding heat is a crucial factor in the strength of AA6061-T6 weldment.
- Although the microhardness technique was able to reveal the lowest hardness regions in the weldment, this technique has limitations when it comes to predicting the failure zone as it shows similar hardness values in the FZ and over-aged planes.
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Al | Cr | Cu | Fe | Mn | Mg | Si | Ti | Zn | |
---|---|---|---|---|---|---|---|---|---|
BM (AA6061-T6) | 98.6 | 0.004 | 0.15 | 0.7 | 0.15 | 0.8 | 0.4 | 0.15 | 0.25 |
FW (ER4043) | 93.3 | --- | 0.3 | 0.8 | 0.05 | 0.05 | 5.25 | 0.2 | 0.1 |
Wire Feeding Speed (mm/s) | Voltage (V) | Ampere (A) | Welding Speed (mm/s) | Angle (Degree) | Shield Gas (Argon) (L/min) |
---|---|---|---|---|---|
114.2 | 23.2 | 174 | 15.2 | 15° | 12 |
Welding Speed (mm/s) | (W/mm3) | (mm) | (mm) | (mm) | Qeff (W) | |
---|---|---|---|---|---|---|
15.2 | 32.7 | 6 | 3 | 4 | 1 | 3150 |
Type of Material | YS (MPa) | UTS (MPa) | Elongation (%) | Hardness (Vickers) |
---|---|---|---|---|
BM (AA6061-T6) | 276 | 310 | 12 | 107 |
FW (ER4043) | 70 | 145 | 22 | 47 |
Peak Temperature °C | ||||
---|---|---|---|---|
Thermocouples | TC1 | TC2 | TC3 | TC4 |
Experimental | 453 | 331 | 276 | 246 |
FEA | 424 | 316 | 266 | 239.8 |
Difference | 6.4% | 4.5% | 3.1% | 2.5% |
Welded Metal | Base Metal | |||||
---|---|---|---|---|---|---|
Description | Test 1 | Test 2 | Ave. | Test1 | Test2 | Ave. |
Yield Stress (MPa) | 153 | 162 | 157.3 | 271 | 271 | 274 |
Ultimate strength (MPa) | 220 | 231 | 226 | 301 | 308 | 305 |
Elongation (%) | 6.8 | 6.7 | 6.8 | 9.1 | 9.8 | 9.4 |
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Arhumah, Z.; Pham, X.-T. Microstructure and Thermal Mechanical Behavior of Arc-Welded Aluminum Alloy 6061-T6. J. Manuf. Mater. Process. 2024, 8, 110. https://doi.org/10.3390/jmmp8030110
Arhumah Z, Pham X-T. Microstructure and Thermal Mechanical Behavior of Arc-Welded Aluminum Alloy 6061-T6. Journal of Manufacturing and Materials Processing. 2024; 8(3):110. https://doi.org/10.3390/jmmp8030110
Chicago/Turabian StyleArhumah, Zeli, and Xuan-Tan Pham. 2024. "Microstructure and Thermal Mechanical Behavior of Arc-Welded Aluminum Alloy 6061-T6" Journal of Manufacturing and Materials Processing 8, no. 3: 110. https://doi.org/10.3390/jmmp8030110