Development of Coated Electrodes with Solid Wire and Flux-Cored Alloyed Wire for Microalloyed Steel Welding
Abstract
:1. Introduction
2. Materials and Methods
2.1. Base Metal and Filler Materials
2.2. Experimental Welding
3. Results and Discussion
3.1. Testing of the Chemical Composition of Pure WM
3.2. Testing of Mechanical Properties of Welding Joints
3.3. The Charpy Impact Test
3.4. Fractographic Analysis of WM Toughness
3.5. Base Metal Microstructure
3.6. Microstructural Analysis of WM
4. Conclusions
- Mechanical–technological properties of WM are primarily characterized by the chemical composition of filler material, i.e., the amount of inserted alloying elements. The total amount of alloying elements inserted into the weld metal from the coated electrode No.1.1 amounted to 2.92%; No.1.2 amounted to 5.66%; No.2.1 amounted to 2.99%; and No.2.2 amounted to 5.13%. The above-mentioned percentages of alloying elements inserted during the technological process of weld metal formation hints at their possible impact on the quality of weld metal, taking into consideration the percentage of their mixture with base metal.
- Testing of weld metal toughness shows that the highest impact on the toughness can be attributed to the chemical composition of base metal and the reaction of elements during the welding procedure. The highest values for toughness were achieved with weld metals created by the No.1.2 and No.2.2 electrodes because, apart from the existence of Ni and Mo in weld metal, this led to the increase in Mn from base metal caused by mixing within the molten weld pool and the reduction in carbon due to its burn-out, which has a favorable impact on the formation of acicular ferrite within WM. It can be concluded that toughness, at lower temperatures, is higher than 25–40%.
- Fractographic analysis of fracture toughness of J55 weld metal created by No.1.1 and No.2.1 electrodes at +20 °C shows that the fracture is ductile along the whole cross-section. Weld metal brittle fracture increases in frequency with specimens which were fractured at −40 °C, where the transcrystalline fracture becomes more prevalent. With specimens that were fractured at −60 °C, the brittle fracture of transcrystalline and intercrystalline character become visible.
- The best quality of welding joints in terms of J55 microalloyed steel of increased strength was achieved by the electrodes No.1.2 (1.34% Mn + 2.850% Ni + 0.59% Mo) and No.2.2 (0.89% Mn + 3.245% Ni + 0.307% Mo), with low heat input (7.5–8.5 kJ/cm).
- Regardless of the fact that the price of flux-cored electrode is higher than the solid wire electrode, it is still a better option, since it yields better weld metal properties related to microalloyed steel if other filler materials are of sufficient quality.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Steel API 5CT | Chemical Composition, wt.% | Mechanical Properties | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
C | Si | Mn | P | S | Al | Cu | Ti | Nb | Re, MPa | Rm, MPa | A5, % | |
J 55 | 0.06 | 0.26 | 1.18 | 0.02 | 0.007 | 0.031 | 0.045 | 0.013 | 0.035 | 497 | 578 | 32 |
API 5CT Standard | 379–552 | >517 | >22.5 |
Designation | Comparative Nomenclature with Other Manufactures | Chemical Composition, wt % | Mechanical Properties of WM | |||||||
---|---|---|---|---|---|---|---|---|---|---|
C | Si | Mn | Ni | Mo | Re, MPa | Rm, MPa | A5, % | KV, J (−40 °C) | ||
IHIS 1.1Ni Mo B | Jesenice, Slovenia: EVB NiMo | 0.06 | 0.40 | 0.90 | 1.10 | 0.35 | 510 | 580–710 | 22 | 47 |
IHIS 2.5Ni Mo B | Plužine, Montenegro: PIVA255BMo | 0.08 | 0.5 | 0.95 | 2.5 | 0.35 | 550–640 | 650–750 | 22–26 | 60–90 |
IHIS 1.1Ni Mo B-pp | Jesenice, Slovenia: Galeb70 | 0.06 | 0.40 | 0.90 | 1.1 | 0.35 | 510 | 580–710 | 22 | 47 |
IHIS 3.3Ni Mo B-pp | Jesenice, Slovenia: EVB 2,5NiMo | 0.06 | 0.45 | 1.15 | 2.30 | 0.40 | 590 | 650–750 | 20 | 47 |
Electrode Designation | Electrode Diameter, mm | Welding Current I, A | Arc Voltage U, V |
---|---|---|---|
IHIS 1.1Ni Mo B | 3.25–smw | 120 | 25 |
IHIS 2.5Ni Mo B | 3.25–smw | 120 | 25 |
IHIS 1.1Ni Mo B-pp | 3.25–fce | 80 | 25 |
IHIS 3.3Ni Mo B-pp | 3.25–fce | 120 | 30 |
No. | Chemical Composition of Clear WM, wt % | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
C | Si | Mn | Cu | Mo | Ni | Cr | S | P | V | Ti | Nb | |
1.1 | 0.04 | 0.32 | 0.95 | 0.13 | 0.31 | 1.04 | 0.09 | 0.010 | 0.013 | / | / | / |
1.2 | 0.09 | 0.59 | 1.34 | 0.08 | 0.59 | 2.85 | 0.073 | 0.02 | 0.023 | / | / | / |
2.1 | 0.015 | 0.111 | 0.68 | 0.067 | 0.241 | 1.868 | / | / | / | <0.003 | <0.003 | <0.003 |
2.2 | 0.026 | 0.546 | 0.89 | 0.090 | 0.307 | 3.245 | / | / | / | 0.014 | 0.009 | <0.003 |
No. | Electrode Designation | Mechanical Properties of WM | Welding Joint | ||||||
---|---|---|---|---|---|---|---|---|---|
Re, MPa | Rm, MPa | A5, % | KV, J (−40 °C) | Rm, MPa | Fracture Location | Bending Angle α, ° | |||
Weld Face | Weld Root | ||||||||
1.1. | IHIS 1.1Ni Mo B | 510 | 580–710 | 22 | 47 | 510 | BM | 180 | 140 |
1.2. | IHIS 2.5Ni Mo B | 550–640 | 650–750 | 22–26 | 60–90 | 550–640 | BM | 180 | 180 |
2.1. | IHIS 1.1Ni Mo B-pp | 510 | 580–710 | 22 | 47 | 510 | BM | 180 | 180 |
2.2. | IHIS 3.3Ni Mo B-pp | 590 | 650–750 | 20 | 47 | 590 | BM | 180 | 180 |
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Bajić, D.; Mrdak, M.; Bajić, N.; Veljić, D.; Rakin, M.; Radosavljević, Z. Development of Coated Electrodes with Solid Wire and Flux-Cored Alloyed Wire for Microalloyed Steel Welding. Materials 2020, 13, 2152. https://doi.org/10.3390/ma13092152
Bajić D, Mrdak M, Bajić N, Veljić D, Rakin M, Radosavljević Z. Development of Coated Electrodes with Solid Wire and Flux-Cored Alloyed Wire for Microalloyed Steel Welding. Materials. 2020; 13(9):2152. https://doi.org/10.3390/ma13092152
Chicago/Turabian StyleBajić, Darko, Mihailo Mrdak, Nikola Bajić, Darko Veljić, Marko Rakin, and Zoran Radosavljević. 2020. "Development of Coated Electrodes with Solid Wire and Flux-Cored Alloyed Wire for Microalloyed Steel Welding" Materials 13, no. 9: 2152. https://doi.org/10.3390/ma13092152