On the Fatigue Strength of Welded High-Strength Steel Joints in the As-Welded, Post-Weld-Treated and Repaired Conditions in a Typical Ship Structural Detail
Weld quality and life extension methods of welded details in ship structures made of high-strength and ultra-high-strength steels are of high importance to overcome the issues related to the fatigue characteristics of welded high-strength steels. The current work experimentally and numerically inves...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-03-01
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| Series: | Journal of Marine Science and Engineering |
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| Online Access: | https://www.mdpi.com/2077-1312/11/3/644 |
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| author | Antti Ahola Kalle Lipiäinen Juuso Lindroos Matti Koskimäki Kari Laukia Timo Björk |
| author_facet | Antti Ahola Kalle Lipiäinen Juuso Lindroos Matti Koskimäki Kari Laukia Timo Björk |
| author_sort | Antti Ahola |
| collection | DOAJ |
| description | Weld quality and life extension methods of welded details in ship structures made of high-strength and ultra-high-strength steels are of high importance to overcome the issues related to the fatigue characteristics of welded high-strength steels. The current work experimentally and numerically investigated the fatigue strength of a longitudinal stiffener detail, typically present in the bulkhead connections of ship hull. Two high-strength steel grades, namely EQ47TM and EQ70QT steels, were studied in welded plate connections using gas metal arc welding with rutile-cored wires. Fatigue tests were carried out on both small-scale specimens under axial and large-scale beam specimens under four-point bending loading. In addition to the joints tested in the as-welded condition, the high-frequency mechanical impact (HFMI) treatment was considered as a post-weld treatment technique in the fatigue test series. Furthermore, the large-scale beam specimens were pre-fatigued until substantial fatigue cracks were observed, after which they were re-tested after weld repairing and post-weld treatments to investigate the potential to rehabilitate fatigue-cracked ship details. The joints in the as-welded condition were performed in accordance with the current design recommendations. Due to the severe transition from the base material to the weld reinforcement in the joints welded with the rutile-cored wire, a successful HFMI treatment required geometrical modification of weld toe using a rotary burr to avoid any detrimental sub-cracks at the HFMI-treated region. Alternatively, the use of solid filler wires could potentially overcome these issues related to the welding quality. Repaired and post-weld-treated welds performed well in the re-tests, and the fatigue strength was almost twice higher than that of tests in the as-welded condition. |
| first_indexed | 2024-03-11T06:20:30Z |
| format | Article |
| id | doaj.art-caf371dc650347638ba00056f460a942 |
| institution | Directory Open Access Journal |
| issn | 2077-1312 |
| language | English |
| last_indexed | 2024-03-11T06:20:30Z |
| publishDate | 2023-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Journal of Marine Science and Engineering |
| spelling | doaj.art-caf371dc650347638ba00056f460a9422023-11-17T11:58:29ZengMDPI AGJournal of Marine Science and Engineering2077-13122023-03-0111364410.3390/jmse11030644On the Fatigue Strength of Welded High-Strength Steel Joints in the As-Welded, Post-Weld-Treated and Repaired Conditions in a Typical Ship Structural DetailAntti Ahola0Kalle Lipiäinen1Juuso Lindroos2Matti Koskimäki3Kari Laukia4Timo Björk5Laboratory of Steel Structures, LUT University, Yliopistonkatu 34, FI-53850 Lappeenranta, FinlandLaboratory of Steel Structures, LUT University, Yliopistonkatu 34, FI-53850 Lappeenranta, FinlandAker Arctic Technology Oy, Merenkulkijankatu 6, FI-00980 Helsinki, FinlandLaboratory of Steel Structures, LUT University, Yliopistonkatu 34, FI-53850 Lappeenranta, FinlandAker Arctic Technology Oy, Merenkulkijankatu 6, FI-00980 Helsinki, FinlandLaboratory of Steel Structures, LUT University, Yliopistonkatu 34, FI-53850 Lappeenranta, FinlandWeld quality and life extension methods of welded details in ship structures made of high-strength and ultra-high-strength steels are of high importance to overcome the issues related to the fatigue characteristics of welded high-strength steels. The current work experimentally and numerically investigated the fatigue strength of a longitudinal stiffener detail, typically present in the bulkhead connections of ship hull. Two high-strength steel grades, namely EQ47TM and EQ70QT steels, were studied in welded plate connections using gas metal arc welding with rutile-cored wires. Fatigue tests were carried out on both small-scale specimens under axial and large-scale beam specimens under four-point bending loading. In addition to the joints tested in the as-welded condition, the high-frequency mechanical impact (HFMI) treatment was considered as a post-weld treatment technique in the fatigue test series. Furthermore, the large-scale beam specimens were pre-fatigued until substantial fatigue cracks were observed, after which they were re-tested after weld repairing and post-weld treatments to investigate the potential to rehabilitate fatigue-cracked ship details. The joints in the as-welded condition were performed in accordance with the current design recommendations. Due to the severe transition from the base material to the weld reinforcement in the joints welded with the rutile-cored wire, a successful HFMI treatment required geometrical modification of weld toe using a rotary burr to avoid any detrimental sub-cracks at the HFMI-treated region. Alternatively, the use of solid filler wires could potentially overcome these issues related to the welding quality. Repaired and post-weld-treated welds performed well in the re-tests, and the fatigue strength was almost twice higher than that of tests in the as-welded condition.https://www.mdpi.com/2077-1312/11/3/644fatiguewelded jointship structurepost-weld treatmentweld repairhigh-strength steel |
| spellingShingle | Antti Ahola Kalle Lipiäinen Juuso Lindroos Matti Koskimäki Kari Laukia Timo Björk On the Fatigue Strength of Welded High-Strength Steel Joints in the As-Welded, Post-Weld-Treated and Repaired Conditions in a Typical Ship Structural Detail Journal of Marine Science and Engineering fatigue welded joint ship structure post-weld treatment weld repair high-strength steel |
| title | On the Fatigue Strength of Welded High-Strength Steel Joints in the As-Welded, Post-Weld-Treated and Repaired Conditions in a Typical Ship Structural Detail |
| title_full | On the Fatigue Strength of Welded High-Strength Steel Joints in the As-Welded, Post-Weld-Treated and Repaired Conditions in a Typical Ship Structural Detail |
| title_fullStr | On the Fatigue Strength of Welded High-Strength Steel Joints in the As-Welded, Post-Weld-Treated and Repaired Conditions in a Typical Ship Structural Detail |
| title_full_unstemmed | On the Fatigue Strength of Welded High-Strength Steel Joints in the As-Welded, Post-Weld-Treated and Repaired Conditions in a Typical Ship Structural Detail |
| title_short | On the Fatigue Strength of Welded High-Strength Steel Joints in the As-Welded, Post-Weld-Treated and Repaired Conditions in a Typical Ship Structural Detail |
| title_sort | on the fatigue strength of welded high strength steel joints in the as welded post weld treated and repaired conditions in a typical ship structural detail |
| topic | fatigue welded joint ship structure post-weld treatment weld repair high-strength steel |
| url | https://www.mdpi.com/2077-1312/11/3/644 |
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