Effect of substrate preheating on the microstructure and hardness of Haynes 25 alloys prepared by laser-directed energy deposition.
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| Title: | Effect of substrate preheating on the microstructure and hardness of Haynes 25 alloys prepared by laser-directed energy deposition. |
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| Authors: | Joo, SeungHo1,2 (AUTHOR), Suh, Joowon1,3 (AUTHOR), Chun, Young-Bum1 (AUTHOR), Han, Heung Nam3 (AUTHOR), Kang, Suk Hoon1 (AUTHOR) shkang77@kaeri.re.kr |
| Source: | Powder Metallurgy. Aug2025, Vol. 68 Issue 4, p320-332. 13p. |
| Subjects: | Nuclear reactors, Dislocation density, Nuclear energy, Substrates (Materials science), Wear resistance |
| Abstract: | Improving wear resistance in Haynes 25 alloy is crucial for the development of flexible nuclear power reactors. Herein, laser-directed energy deposition (L-DED)-assisted substrate preheating is reported as an efficient strategy to alleviate cracks and pores in the alloy. The substrate-preheated alloy (300PH) exhibited no microcracks and a 45.2% reduction in pore fraction compared to the non-preheated alloy (NonPH). Moreover, 300PH exhibited a 7% lower Vickers microhardness than that of NonPH, whereas its nanohardness decreased by 3.6 and 2.9% in the dendritic and interdendritic regions, respectively. Dislocation strengthening was the dominant contributor to the theoretical yield strength and microhardness. Furthermore, preheating influenced the dislocation contribution substantially by reducing the residual stress leading to reductions in geometrically necessary dislocations and total dislocation density, thereby reducing microhardness. Therefore, preheating the substrate mitigated pores and cracks, effectively improved the structural integrity of L-DED Haynes 25 alloy, without significantly compromising the hardness. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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| Abstract: | Improving wear resistance in Haynes 25 alloy is crucial for the development of flexible nuclear power reactors. Herein, laser-directed energy deposition (L-DED)-assisted substrate preheating is reported as an efficient strategy to alleviate cracks and pores in the alloy. The substrate-preheated alloy (300PH) exhibited no microcracks and a 45.2% reduction in pore fraction compared to the non-preheated alloy (NonPH). Moreover, 300PH exhibited a 7% lower Vickers microhardness than that of NonPH, whereas its nanohardness decreased by 3.6 and 2.9% in the dendritic and interdendritic regions, respectively. Dislocation strengthening was the dominant contributor to the theoretical yield strength and microhardness. Furthermore, preheating influenced the dislocation contribution substantially by reducing the residual stress leading to reductions in geometrically necessary dislocations and total dislocation density, thereby reducing microhardness. Therefore, preheating the substrate mitigated pores and cracks, effectively improved the structural integrity of L-DED Haynes 25 alloy, without significantly compromising the hardness. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 00325899 |
| DOI: | 10.1177/00325899251343440 |
