A Study on Cross-Shaped Structure of Invar Material Using Cold Wire Laser Fillet Welding (PART I: Feasibility Study for Weldability)
Abstract
:1. Introduction
2. Experiment
2.1. Specimen for Experiment
2.2. Laser Welding Using Fiber Laser System
2.3. Examination of Cross-Section
2.4. Experimental Conditions of Cold Wire Laser Welding Using Fiber Laser
3. Results
3.1. 1.5 mm Thickness of Invar Experiment
3.2. 3.0 mm Thickness of Invar Experiment
4. Discussion
5. Conclusions
- (1)
- When fabricating a cross-shaped structure through general TIG welding, fillet welding should be performed for each of the four corners with PJP. However, fillet welding is performed for two corners only to reduce the number of weld passes if the fiber laser fillet welding method proposed in this study is used because of the deep keyhole of CJP. In addition, the overall welding time can be reduced to less than one quarter of the time required for TIG welding, because laser welding using fiber laser speed is two times faster.
- (2)
- Using laser power, wire feeding speed, working angle, and beam location as variables, the welding conditions for two corner fillet welding were determined. At this time, welding was performed using a trial and error method, in which each variable was changed and its feasibility was verified through cross-section examination.
- (3)
- To fabricate a cross-shaped Invar structure with 1.5 mm thickness, welding feasibility was achieved under the conditions of laser power of 1.75 kW, wire feeding speed of 1.5 m/min, working angle of 70°, and beam location of 0 mm. For the 3.0 mm Invar structure, welding feasibility was achieved under the conditions of laser power of 3.0 kW, wire feeding speed of 3.5 m/min, working angle of 70°, and beam location of 0.5 mm. Although those conditions are the best trials of this research, there could be other conditions for the feasibility for weldability.
- (4)
- This study is a preliminary study for improving the fabrication method of cross-shaped Invar structures using fiber laser fillet welding. Subsequent studies should aim to verify the soundness of such welded structures through tests of mechanical properties such as hardness, strength, and fatigue, in addition to checking for welding defects using ultrasonic and X-ray testing. Moreover, for obtaining the metallurgical soundness, a follow-up study will be performed including finding the condition for the removal of the porosity after welding.
Author Contributions
Funding
Conflicts of Interest
References
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Materials | CTE (mm/mmK) | Young’s Modulus (GPa) | Density (kg/m3) |
---|---|---|---|
Invar | 1.2 × 10−6 | 148 | 8100 |
A240-304L | 17.3 × 10−6 | 193 | 8000 |
AL5083-O | 23.8 × 10−6 | 71 | 2660 |
Material | Composition (%) | ||||
---|---|---|---|---|---|
Invar (ASTM F1684) | Ni | Mo | C | Mn | Fe |
36 | ~0.5 | ~0.1 | ~0.06 | bal. | |
P | S | Si | Cr | - | |
~0.025 | ~0.025 | ~0.35 | ~0.5 | - |
Variables | Cases |
---|---|
Laser Power (kW) | 1.25, 1.75, 2.00, 2.25 |
Wire Feeding Speed (m/min) | 1.00, 1.25, 1.50, 1.75 |
Working Angle (°) | 60, 70, 80 |
Welding Speed (m/min) | 1.0 |
Beam Location (mm) | 0 |
Variables | Cases |
---|---|
Laser Power (kW) | 1.75, 2.25, 2.75, 3.25 |
Wire Feeding Speed (m/min) | 1.75, 2.00, 2.25, 2.50, 3.00, 3.50 |
Working Angle (°) | 70, 75, 80, 85 |
Welding Speed (m/min) | 1.0 |
Beam Location (mm) | 0.25, 0.5, 1.0 |
Variable | Value | Variable | Value |
---|---|---|---|
Laser Power (kW) | 1.25 | Working Angle (°) | 60, 70, 80 |
Wire Feeding Speed (m/min) | 1.0 | Beam Location (mm) | 0.0 |
Variable | Value | Variable | Value |
---|---|---|---|
Laser Power (kW) | 1.75, 2.0, 2.25 | Working Angle (°) | 70 |
Wire Feeding Speed (m/min) | 1.0 | Beam Location (mm) | 0.0 |
Variable | Value | Variable | Value |
---|---|---|---|
Laser Power (kW) | 1.75, 2.0 | Working Angle (°) | 70 |
Wire Feeding Speed (m/min) | 1.0, 1.25, 1.50, 1.75 | Beam Location (mm) | 0.0 |
Variable | Value | Variable | Value |
---|---|---|---|
Laser Power (kW) | 1.75, 2.25, 2.75, 3.25 | Working Angle (°) | 70 |
Wire Feeding Speed (m/min) | 1.5 | Beam Location (mm) | 0.0 |
Variable | Value | Variable | Value |
---|---|---|---|
Laser Power (kW) | 3.0, 3.25, 3.5 | Working Angle (°) | 70 |
Wire Feeding Speed (m/min) | 1.5 | Beam Location (mm) | 0.5, 1.0 |
Variable | Value | Variable | Value |
---|---|---|---|
Laser Power (kW) | 3.0 | Working Angle (°) | 70 |
Wire Feeding Speed (m/min) | 1.75, 2.0, 2.25, 2.5, 3.0, 3.5 | Beam Location (mm) | 0.25, 0.5 |
Welding Type | Welding Speed (m/min) | Number of Welding | Welding Time (s) (5 m Length Structure) |
---|---|---|---|
Fiber Laser Fillet Welding | 1.0 | 2 | 600 |
TIG Welding | 0.5 | 4 | 2400 |
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Kim, D.-S.; Pyo, C.; Kim, J.; Kim, J.; Lee, H.-K. A Study on Cross-Shaped Structure of Invar Material Using Cold Wire Laser Fillet Welding (PART I: Feasibility Study for Weldability). Metals 2020, 10, 1385. https://doi.org/10.3390/met10101385
Kim D-S, Pyo C, Kim J, Kim J, Lee H-K. A Study on Cross-Shaped Structure of Invar Material Using Cold Wire Laser Fillet Welding (PART I: Feasibility Study for Weldability). Metals. 2020; 10(10):1385. https://doi.org/10.3390/met10101385
Chicago/Turabian StyleKim, Du-Song, Changmin Pyo, Jaewoong Kim, Jisun Kim, and Hee-Keun Lee. 2020. "A Study on Cross-Shaped Structure of Invar Material Using Cold Wire Laser Fillet Welding (PART I: Feasibility Study for Weldability)" Metals 10, no. 10: 1385. https://doi.org/10.3390/met10101385