Research on Influential Mechanism of HAZ Impact Toughness for Shipbuilding Steel with Mg Addition
Abstract
:1. Introduction
2. Materials and Methods
- —welding current, A,
- —welding voltage, V,
- —welding speed, cm/s.
3. Results
3.1. Impact Testing
3.2. Impact Fracture
3.2.1. Macroscopic Feature
3.2.2. Microscopic Feature
4. Discussion
4.1. Influence of Welding Heat Input
4.2. Analysis of Metallographic Structures
4.3. Analysis of Inclusions
5. Conclusions
- (1)
- The HAZ of three kinds of thickness plates induced much IAF; with Mg addition, the inclusion dimension had been reduced effectively, and the IAF induced ability of the inclusions had also been improved. If the original metallographic microstructure of steel was coarse, the pinning effect of the inclusions would be reduced significantly, and the microstructure of HAZ would be coarsened and the impact toughness of HAZ would be decreased, so there is a certain matching relationship between the metallographic microstructure and the inclusion dimension.
- (2)
- Mg is not the primary cause of the IAF inducing, but Mg can effectively reduce the size of inclusions, and thus increase the inclusion ability of IAF inducing.
- (3)
- The difference of HAZ impact toughness with different welding heat input and different impact temperature is significant; considering the influence of welding heat input and metallographic microstructure on the impact toughness of HAZ, the welding heat load had a far greater effect than the metallographic microstructure on the ductile–brittle transition temperature.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Composition | C | Si | Mn | S | P | Al | Ti | Mo | V | Nb | Mg |
---|---|---|---|---|---|---|---|---|---|---|---|
content | 0.08 | 0.20 | 1.40 | 0.005 | 0.015 | 0.01 | 0.015 | 0.07 | 0.04 | 0.04 | 0.005 |
Thickness (mm) | Input Line Energy (KJ/cm) | Welding Speed (m/h) | Welding Wire Diameter (mm) | Welding Wire Kinds | Fore Wire | Hind Wire | ||
---|---|---|---|---|---|---|---|---|
Current | Voltage | Current | Voltage | |||||
(A) | (V) | (A) | (V) | |||||
16 | 50 | 19.6 | 4.0 | 10Mn2 | 780 | 35 | ||
25 | 100 | 24 | 5.0 + 5.0 | 10Mn2 + SJ501 | 1000 | 41 | 700 | 37 |
40 | 150 | 22.7 | 5.0 + 5.0 | 10Mn2 + SJ501 | 1200 | 44 | 1000 | 42 |
Thickness/mm | Input Line Energy/kJ/cm | Impact Temperature/°C | Impact Absorbed Energy/J | Averaged Value/J | ||
---|---|---|---|---|---|---|
16 | 50 | −20 | 197.3 | 166.7 | 172.0 | 178.7 |
−40 | 89.6 | 49.0 | 74.3 | 71.0 | ||
25 | 100 | −20 | 42.5 | 91.4 | 38.6 | 57.5 |
−40 | 51.8 | 30.2 | 17.4 | 33.1 | ||
40 | 150 | −20 | 198.9 | 189.5 | 197.6 | 195.3 |
−40 | 32.9 | 35.7 | 27.5 | 32.0 |
Thickness of Steel Plate | 0–5 μm | 5–10 μm | 10–15 μm | 15–20 μm |
---|---|---|---|---|
16 mm | 83 | 14 | 16 | 14 |
25 mm | 100 | 20 | 8 | 2 |
40 mm | 67 | 26 | 6 | 10 |
Total Scan Area S1 (mm2) | Number of Microscopic Inclusions | Number of Microscopic Inclusions per Unit Area (/mm2) | Total Area of Microscopic Inclusions S2 (mm2) | S2/S1 (%) | |
---|---|---|---|---|---|
Normal (without Mg) | 35.4 | 2042 | 57.7 | 0.023 | 0.065 |
Experiment (with Mg) | 30.0 | 2211 | 73.7 | 0.017 | 0.057 |
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Li, H.-r.; Sun, L.-g.; Zhu, L.-g.; Liu, Y.-s.; Li, Y.-g. Research on Influential Mechanism of HAZ Impact Toughness for Shipbuilding Steel with Mg Addition. Metals 2018, 8, 584. https://doi.org/10.3390/met8080584
Li H-r, Sun L-g, Zhu L-g, Liu Y-s, Li Y-g. Research on Influential Mechanism of HAZ Impact Toughness for Shipbuilding Steel with Mg Addition. Metals. 2018; 8(8):584. https://doi.org/10.3390/met8080584
Chicago/Turabian StyleLi, Hui-rong, Li-gen Sun, Li-guang Zhu, Yun-song Liu, and Yun-gang Li. 2018. "Research on Influential Mechanism of HAZ Impact Toughness for Shipbuilding Steel with Mg Addition" Metals 8, no. 8: 584. https://doi.org/10.3390/met8080584