Effect of local carbide formation behavior on repair weld liquation cracking susceptibility for long-term-serviced 247LC superalloy
This study assessed the liquation cracking temperature range (LCTR) for 247LC superalloy repair welds subjected to long-term and high-temperature exposure. To achieve this, the exposed specimens underwent simulations at 1273 K for 500, 1000, 3000, and 5000 h to replicate the long-term service condit...
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| Format: | Article |
| Language: | English |
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Elsevier
2024-01-01
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| Series: | Journal of Materials Research and Technology |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2238785423030673 |
| _version_ | 1827368368281223168 |
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| author | Hye-Eun Jeong Seong-Moon Seo Eun-Joon Chun |
| author_facet | Hye-Eun Jeong Seong-Moon Seo Eun-Joon Chun |
| author_sort | Hye-Eun Jeong |
| collection | DOAJ |
| description | This study assessed the liquation cracking temperature range (LCTR) for 247LC superalloy repair welds subjected to long-term and high-temperature exposure. To achieve this, the exposed specimens underwent simulations at 1273 K for 500, 1000, 3000, and 5000 h to replicate the long-term service conditions of gas turbines. Spot-Varestraint testing was employed to quantitatively measure LCTR variations. The metallurgical mechanism of the evaluated LCTR in the exposed 247LC superalloys was elucidated by analyzing the microstructural characteristics at the liquation cracking surface and performing thermodynamic calculations. The LCTR was evaluated to be 410 K for specimens exposed for 500 h, 440 K for 1000 h, 385 K for 3000 h, and 610 K for 5000 h. This indicates that the liquation cracking susceptibility of the repaired weld heat-affected zone significantly increased during the long-term service of the 247LC superalloy. After 5000 h of exposure, the formation of fine MC, M6C, and M23C6 carbides on the liquation cracking surface was characterized using transmission electron microscopy. The welding metallurgical mechanism underlying the severe liquation cracking susceptibility can be attributed to the fractions of MC (liquation initiation temperature: 1125–1356 K) and M6C (liquation initiation temperature: 1390–1420 K), which have lower liquation initiation temperatures than the solidus of the 247LC alloy (1530 K). Notably, the area fraction of MC and M6C increased during 5000 h of exposure, which led to an increase in LCTR from 410 K to 610 K. |
| first_indexed | 2024-03-08T09:29:17Z |
| format | Article |
| id | doaj.art-d898ebcc155d48e4ae6df64d59452ae7 |
| institution | Directory Open Access Journal |
| issn | 2238-7854 |
| language | English |
| last_indexed | 2024-03-08T09:29:17Z |
| publishDate | 2024-01-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Materials Research and Technology |
| spelling | doaj.art-d898ebcc155d48e4ae6df64d59452ae72024-01-31T05:43:15ZengElsevierJournal of Materials Research and Technology2238-78542024-01-0128110122Effect of local carbide formation behavior on repair weld liquation cracking susceptibility for long-term-serviced 247LC superalloyHye-Eun Jeong0Seong-Moon Seo1Eun-Joon Chun2Department of Materials System Engineering, Pukyong National University, Busan, 48513, Republic of KoreaHigh Temperature Materials Group, Korea Institute of Materials Science, Changwon, 51508, Republic of KoreaDepartment of Materials System Engineering, Pukyong National University, Busan, 48513, Republic of Korea; Corresponding author.This study assessed the liquation cracking temperature range (LCTR) for 247LC superalloy repair welds subjected to long-term and high-temperature exposure. To achieve this, the exposed specimens underwent simulations at 1273 K for 500, 1000, 3000, and 5000 h to replicate the long-term service conditions of gas turbines. Spot-Varestraint testing was employed to quantitatively measure LCTR variations. The metallurgical mechanism of the evaluated LCTR in the exposed 247LC superalloys was elucidated by analyzing the microstructural characteristics at the liquation cracking surface and performing thermodynamic calculations. The LCTR was evaluated to be 410 K for specimens exposed for 500 h, 440 K for 1000 h, 385 K for 3000 h, and 610 K for 5000 h. This indicates that the liquation cracking susceptibility of the repaired weld heat-affected zone significantly increased during the long-term service of the 247LC superalloy. After 5000 h of exposure, the formation of fine MC, M6C, and M23C6 carbides on the liquation cracking surface was characterized using transmission electron microscopy. The welding metallurgical mechanism underlying the severe liquation cracking susceptibility can be attributed to the fractions of MC (liquation initiation temperature: 1125–1356 K) and M6C (liquation initiation temperature: 1390–1420 K), which have lower liquation initiation temperatures than the solidus of the 247LC alloy (1530 K). Notably, the area fraction of MC and M6C increased during 5000 h of exposure, which led to an increase in LCTR from 410 K to 610 K.http://www.sciencedirect.com/science/article/pii/S2238785423030673247LC superalloyRepair weldingLiquation cracking temperature rangeSpot-varestraint testCarbide |
| spellingShingle | Hye-Eun Jeong Seong-Moon Seo Eun-Joon Chun Effect of local carbide formation behavior on repair weld liquation cracking susceptibility for long-term-serviced 247LC superalloy Journal of Materials Research and Technology 247LC superalloy Repair welding Liquation cracking temperature range Spot-varestraint test Carbide |
| title | Effect of local carbide formation behavior on repair weld liquation cracking susceptibility for long-term-serviced 247LC superalloy |
| title_full | Effect of local carbide formation behavior on repair weld liquation cracking susceptibility for long-term-serviced 247LC superalloy |
| title_fullStr | Effect of local carbide formation behavior on repair weld liquation cracking susceptibility for long-term-serviced 247LC superalloy |
| title_full_unstemmed | Effect of local carbide formation behavior on repair weld liquation cracking susceptibility for long-term-serviced 247LC superalloy |
| title_short | Effect of local carbide formation behavior on repair weld liquation cracking susceptibility for long-term-serviced 247LC superalloy |
| title_sort | effect of local carbide formation behavior on repair weld liquation cracking susceptibility for long term serviced 247lc superalloy |
| topic | 247LC superalloy Repair welding Liquation cracking temperature range Spot-varestraint test Carbide |
| url | http://www.sciencedirect.com/science/article/pii/S2238785423030673 |
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