Auburn University in the United States in-depth study of the impact of construction direction on the structural integrity of 3D printed aluminum parts

Introduction: in manymineral powderMaterial3D printingmiddle,Aluminum alloy powderAt the end it seems to be a special existence. This has a lot to do with the physical and chemical properties of the aluminum alloy powder itself. The flammable, easily oxidized, and moisture-absorbing properties of the fine aluminum alloy powder have brought huge troubles to its production, storage and transportation. In addition, the poor fluidity and high laser reflectivity of aluminum alloy powder also bring great challenges to its printing process.

However, because of its light weight, high strength, high thermal conductivity, corrosion resistance, electrical conductivity and many other excellent characteristics, aluminum alloy is
aviation
aerospace
,national defense
Military industry
,
car
,electronic,
architecture
And other fields have huge application potential.Therefore, in order to promote the further application of aluminum alloy in the field of metal printing, scientists from all over the world are3D printingExploring aspects.

September 21, 2021, by Auburn University andEOSA research team composed of engineers from North American companies conducted an in-depth study on the direction of construction3D printingThe influence of aluminum (Al) alloy structural integrity.The team tested the 5 most popular aluminum alloy powders, including AlSi10Mg, Scalmalloy, QuesTekAl, Addalloy® 5T (AD1) and AlF357.They melt by using a powder bed3D printingTechnology, studied how the construction direction changes characteristics such as part microstructure, material porosity and fatigue behavior, these characteristics are indispensable for understanding whether materials are suitable for high-pressure industrial applications. The research paper explains: “The use of aluminum alloys for additive manufacturing has recently received great attention, especially in the aerospace industry. This has promoted the introduction of new high-strength aluminum alloys and made the additive manufacturing process more compatible. However, Before deploying these newly developed aluminum alloys in safety-critical load-bearing applications, it is vital to investigate their structural integrity.”

△SEM images of 5 different aluminum powders.Picture from Auburn University

The rise of aluminum in additive manufacturing

With metal3D printingQuickly become automotive, defense andMedical treatmentNew material innovations are constantly emerging as strategic tools in other industries. Aluminum alloys in particular are known for their high strength-to-weight ratio, hardenability and excellent corrosion resistance, making them the primary choice for various applications in the aerospace and racing fields.However, according to researchers at Auburn University,3D printingAluminum alloys are often more challenging than other materials. The powder particles are very light, exhibit poor fluidity, attract moisture, have high thermal conductivity, and are easily oxidized.This series of questions increased3D printingThe defect risk of aluminum parts is known to be harmful to the mechanical properties (especially fatigue properties) of any material. Interestingly, the construction direction of the part has also proven to be a major factor in the type, size and frequency of defects.This is attributed to the changes in thermal history experienced by components in different directions, so it is necessary to evaluate how the construction direction affects3D printingFatigue behavior of aluminum parts.

△Scalmalloy’s aerodynamic sports winglet. Photo from APWORKS

Influence of construction direction on structural integrity

This research involves in the vertical and horizontal directions3D printingAlSi10Mg, Scalmalloy, QuesTek Al, AD1 and AlF357 samples.First, the construction direction has no significant effect on the grain structure of aluminum parts. However, when it comes to defects, the volumetric defect level of horizontal specimens is much higher than that of vertical specimens. Scalmalloy and AD1 show the lowest defect density variation between vertical and horizontal builds because of the relatively low thermal conductivity of these two alloys. Comparing these alloys with each other, the fatigue performance of AD1 is better than that of AlSi10Mg, QuesTek Al and AlF357, regardless of the direction of construction. This is due to the low defect density, high tensile strength and high elongation of AD1. Although the fatigue performance of the horizontal Scalmalloy component is slightly weaker than that of the horizontal AD1 component, the fatigue life of the vertical specimens of the two alloys is equivalent.

The final conclusion of the study is: “Although the results of the study did not provide overall fatigue performance, for these five popular LB-PBF aluminum alloys today, we can help AM users based on the data constructed in different directions and the results obtained. Choose the right aluminum alloy for their application. Nevertheless, AM users may need to generate more test data for each alloy before using it in a specific application.”

△ Among the five alloys, the porosity of the horizontal structure is significantly higher than the porosity of the vertical structure.Picture from Auburn University

Further details of the research can be found in the title “Structural integrity of additively manufactured aluminum alloys: Effects of build orientation on microstructure, porosity, and fatigue behavior”. It was co-written by PD Nezhadfar, Spencer Thompson and others.

Links to related papers:https://www.sciencedirect.com/sc … i/S2214860421004528

In addition, earlier this summer, Italy3D printingThe service provider BEAMIT has developed a set of3D printingParameter statistics of high-performance Al2024 aluminum alloy. They believe that aluminum performs better than other similar alloys at room temperature and high temperature, and is an ideal material for the production of durable chassis, suspension and engine components for racing applications.

Recently, the UK’s Digital Manufacturing Centre (DMC) has just become Scalmalloy production3D printingThe certified supplier of the component. As part of supplier certification requirements, DMC
3D printingA set of Scalmalloy parts was installed and inspected by APWORKS, the developer of the material. The test results show that the quality of the parts achieved makes DMC rank among the top 1% of global Scalmalloy parts suppliers.

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Auburn University in the United States in-depth study of the impact of construction direction on the structural integrity of 3D printed aluminum parts

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