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A solution to the hot cracking problem for aluminium alloys manufactured by laser beam melting
Acta Materialia ( IF 9.4 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.actamat.2020.07.015
Mathieu Opprecht , Jean-Paul Garandet , Guilhem Roux , Camille Flament , Mathieu Soulier

Abstract A method to eliminate hot cracking phenomena for aluminium alloys in Laser Beam Melting (LBM) is presented in this paper, focused here on the 6061 alloy. 6061 is a precipitation-hardened aluminium alloy, containing magnesium and silicon as its major alloying elements. This alloy, commonly used in the aeronautic and automotive industries, thanks to its excellent weight to strength ratio and high thermal conductivity, is particularly prone to hot cracking, in particular during LBM processing. The solution to remove cracks proposed in the present paper is to induce grain refinement to avoid the development of large columnar structures. To this end, various quantities of Yttrium Stabilized Zirconia (YSZ) are added to an Al6061 base powder using a dry mixing (TurbulaⓇ) procedure. Experiments highlight a grain refinement effect depending on the added YSZ quantity. From 1 vol% on, SEM and EBSD images reveal an equiaxed-columnar bimodal grain microstructure. Results show that the addition of 2 vol% YSZ allows to fully avoid cracks due to a continuous equiaxed band at melt pool boudaries. Additionally, TEM and DRX investigations provide new insights into the becoming of added particles along the printing process. The experimental results are then discussed on the basis of a number of existing solidification models, with a focus on the necessary conditions for the establishment of an equiaxed solidification regime.

中文翻译:

激光束熔炼铝合金热裂问题的解决方案

摘要 本文提出了一种消除铝合金激光束熔化 (LBM) 热裂现象的方法,这里重点介绍 6061 合金。6061 是一种沉淀硬化铝合金,含有镁和硅作为其主要合金元素。这种合金通常用于航空和汽车行业,由于其出色的重量强度比和高导热性,特别容易发生热裂纹,尤其是在 LBM 加工过程中。本文提出的去除裂纹的解决方案是诱导晶粒细化以避免大柱状结构的发展。为此,使用干混 (TurbulaⓇ) 程序将不同数量的钇稳定氧化锆 (YSZ) 添加到 Al6061 基础粉末中。实验突出了取决于添加的 YSZ 数量的晶粒细化效果。从 1 vol% 开始,SEM 和 EBSD 图像显示等轴柱状双峰晶粒微观结构。结果表明,添加 2 vol% YSZ 可以完全避免由于熔池边界处的连续等轴带造成的裂纹。此外,TEM 和 DRX 研究提供了对打印过程中添加颗粒的形成的新见解。然后在许多现有凝固模型的基础上讨论实验结果,重点是建立等轴凝固制度的必要条件。结果表明,添加 2 vol% YSZ 可以完全避免由于熔池边界处的连续等轴带造成的裂纹。此外,TEM 和 DRX 研究提供了对打印过程中添加颗粒的形成的新见解。然后在许多现有凝固模型的基础上讨论实验结果,重点是建立等轴凝固制度的必要条件。结果表明,添加 2 vol% YSZ 可以完全避免由于熔池边界处的连续等轴带造成的裂纹。此外,TEM 和 DRX 研究提供了对打印过程中添加颗粒的形成的新见解。然后在许多现有凝固模型的基础上讨论实验结果,重点是建立等轴凝固制度的必要条件。
更新日期:2020-09-01
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