Improving the mechanical properties of laser powder bed fused AlSi10Mg alloys by eliminating the inevitable micro-voids via hot forging

Rapid Prototyping Journal Pub Date : 2024-02-29 DOI:10.1108/rpj-06-2023-0202

Jie Wan, Biao Chen, Jianghua Shen, K. Kondoh, Shuiqing Liu, Jinshan Li

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Abstract

Purpose The metallic alloys and their components fabricated via laser powder bed fusion (LPBF) suffer from the microvoids formed inevitably due to the extreme solidification rate during fabrication, which are impossible to be removed by heat treatment. This paper aims to remove those microvoids in as-built AlSi10Mg alloys by hot forging and enhance their mechanical properties. Design/methodology/approach AlSi10Mg samples were built using prealloyed powder with a set of optimized LPBF parameters, viz. 350 W of laser power, 1,170 mm/s of scan speed, 50 µm of layer thickness and 0.24 mm of hatch spacing. As-built samples were preheated to 430°C followed by immediate pressing with two different thickness reductions of 10% and 35%. The effect of hot forging on the microstructure was analyzed by means of X-ray diffraction, scanning electron microscopy, electron backscattered diffraction and transmission electron microscopy. Tensile tests were performed to reveal the effect of hot forging on the mechanical properties. Findings By using hot forging, the large number of microvoids in both as-built and post heat-treated samples were mostly healed. Moreover, the Si particles were finer in forged condition (∼150 nm) compared with those in heat-treated condition (∼300 nm). Tensile tests showed that compared with heat treatment, the hot forging process could noticeably increase tensile strength at no expense of ductility. Consequently, the toughness (integration of tensile stress and strain) of forged alloy increased by ∼86% and ∼24% compared with as-built and heat-treated alloys, respectively. Originality/value Hot forging can effectively remove the inevitable microvoids in metals fabricated via LPBF, which is beneficial to the mechanical properties. These findings are inspiring for the evolution of the LPBF technique to eliminate the microvoids and boost the mechanical properties of metals fabricated via LPBF.

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通过热锻消除不可避免的微空洞，改善激光粉末床熔融 AlSi10Mg 合金的机械性能

目的通过激光粉末床熔融（LPBF）制造的金属合金及其部件在制造过程中由于极高的凝固速度不可避免地会形成微空洞，这些微空洞无法通过热处理去除。本文旨在通过热锻去除已成型的 AlSi10Mg 合金中的这些微空洞，并提高其机械性能。设计/方法/方法使用预合金化粉末制造 AlSi10Mg 样品，并使用一组优化的 LPBF 参数，即 350 W 的激光功率、1,170 mm/s 的扫描速度、50 µm 的层厚和 0.24 mm 的间距。坯件预热至 430°C，然后立即压制，厚度分别减少 10%和 35%。通过 X 射线衍射、扫描电子显微镜、电子反向散射衍射和透射电子显微镜分析了热锻对微观结构的影响。研究结果通过热锻，坯料和热处理后样品中的大量微空洞大部分都得到了愈合。此外，锻造状态下的硅颗粒（∼150 nm）比热处理状态下的（∼300 nm）更细。拉伸试验表明，与热处理相比，热锻工艺在不影响延展性的情况下明显提高了拉伸强度。因此，锻造合金的韧性（拉伸应力和应变的整合）比原状合金和热处理合金分别提高了 ∼ 86% 和 ∼ 24%。这些发现对 LPBF 技术的发展具有启发意义，可消除微空洞并提高 LPBF 制成的金属的机械性能。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Rapid Prototyping Journal

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