Control of the Molten Pool Morphology and Crystal Growth Behavior in Laser Powder Deposition of Single-Crystal Superalloy via Adjusting the Defocusing Amount and Scanning Speed
Control of the Molten Pool Morphology and Crystal Growth Behavior in Laser Powder Deposition of Single-Crystal Superalloy via Adjusting the Defocusing Amount and Scanning Speed
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通过调节散焦量和扫描速度控制单晶高温合金激光粉末沉积熔池形貌和晶体生长行为
DOI：
10.1007/s11666-022-01446-5
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发表时间：
2022-09
影响因子：
3.1
通讯作者：
Liu Xiaochu
中科院分区：
文献类型：
--
作者：
Liu Zhaoyang;Liang Zhongwei;Zou Tao;Liu Xiaochu
稳定地控制修复区的单晶性是激光加法修复单晶元件的一个长期挑战。通过单道实验和改进的数学模型，研究了激光散焦量和扫描速度对激光粉末沉积单晶高温合金熔池形态和晶体生长行为的耦合影响。为验证优化工艺参数的实用性，进行了多层实验。结果表明，散焦量可以通过改变激光与粉末的相互作用距离来有效地调整激光能量强度分布，从而调整熔池形态和晶体生长行为。随着离焦量从− 3变为 + 3，熔池的趾角急剧增大，在趾缘形成非理想的柱状晶。激光扫描速度的提高缩小了熔池尺寸，抑制了杂散晶和非理想柱状晶的形成，增强了杂散晶的全重熔能力。耦合剪裁负离焦量和适当的扫描速度(− 3 mm和9 mm/S在给定条件下为最佳扫描速度)有利于柱状枝晶的外延生长连续性，并在激光SX修复过程中再现完整的单晶组织。
Stably controlling the monocrystalline nature in the repaired zone is a longstanding challenge for the laser additively repair of single-crystal components. In this study, the coupling effect of laser defocusing amount and scanning speed on the molten pool morphology and associated crystal growth behaviors in laser powder deposition of single-crystal superalloy was studied through single-track experiments and an improved mathematical model. Multi-layer experiments were conducted to verify the practicability of optimized processing parameters. The results indicated that the defocusing amount can effectively adjust the laser energy intensity distribution through changing the laser-powder interaction distance and resultantly tailor the molten pool morphology and associated crystal growth behaviors. With the defocusing amount changing from − 3 to + 3 mm, the toe angle of molten pool increases dramatically and induces the formation of nonideal columnar crystals at the toe edge. The increase in laser scanning speed shrinks the molten pool size, restrains the formation of stray grains and nonideal columnar crystals, and enhances the total-remelting ability of stray grains. Coupling tailoring negative defocusing amount and proper scanning speed (− 3 mm and 9 mm/s are optimal under the given conditions) benefits the epitaxial-growth continuity of columnar dendrites and reproduces complete monocrystalline structure in laser SX-repair process.
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DOI：
10.1007/s11661-013-2178-9
发表时间：
2014-04-01
影响因子：
2.8
作者：
Liu, Zhaoyang;Qi, Huan
通讯作者：
Qi, Huan
DOI：
10.1016/j.msea.2016.05.046
发表时间：
2016-06-21
影响因子：
6.4
作者：
Helmer, H.;Bauereiss, A.;Koerner, C.
通讯作者：
Koerner, C.
基体晶体取向对镍基高温合金激光粉末沉积晶体生长和微观结构形成的影响
影响因子：
9.4
作者：
Liu, Zhaoyang;Qi, Huan
通讯作者：
Qi, Huan
DOI：
10.1007/bf02650147
发表时间：
1989-06
期刊：
Metallurgical Transactions A
影响因子：
--
作者：
M. Rappaz;S. David;J. Vitek;L. Boatner
通讯作者：
M. Rappaz;S. David;J. Vitek;L. Boatner
影响因子：
2.1
作者：
R. Vilar;A. Almeida
通讯作者：
R. Vilar;A. Almeida