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Aluminum Alloys: Researchers Explore the Microstructure-Property Relationship in Metal 3D Printing

by • July 31, 2016 • No Comments

300px-OSHlogoI’m always befuddled in these days by those on the periphery of the 3D printing industry who cry that the sky has fallen, and the innovation is over and dead. We see either disappointment over the lack of 3D printing devices on the homefront (I idea we may all have one in our homes by now!), disdain for the learning curve involved in in fact making things (this is too complex!), or impatience in seeing a true revolution that was supposed to send many down the tubes for great (what? The big companies we idea can crumble have been invested in 3D printing for decades?).

Many yet, know that instead of being eager to expire, in many ways 3D printing is yet in its infancy. If you appear around at what’s being generated, that’s obvious. Whilst companies (and countries) may be stealing the headlines with all things of 3D printed cars and autonomous mini-buses to 3D printed office buildings, many all things is yet in the first stages, with much necessary refinement ahead.

3D printing with metal is a ideal example. Whilst those on the outskirts are occupied declaring it over, researchers around the world are only digging in deeper. The evidence may be complex to deny on any level as we see 3D printing with metal a massive priority in production facilities for giants like GE and Alcoa, and we see researchers appearing into just about every aspect of this materials science of porosity issues to issues with operator handling. Development and functionality of a range of metal alloys is at the top of the list for discussion and exploration, yet, thinking the durablity and power 3D printing in metal materials can contribute to manufacturers hoping to improve their products—and the bottom line.

Recently, researchers at Michigan Tech Open Sustainability Technology (MOST) Lab began working together on a project to explore the use of common aluminum alloys in 3D printing. ‘Structure Property Relationships of Common Aluminum Weld Alloys Utilized as Feedstock for GMAW-based 3D Metal Printing,’ authored by Amberlee S. Haselhuhn, Michael W. Buhr, Bas Wijnen, Paul G. Sanders, and Joshua M. Pearce was not long ago published in Materials Science and Engineering. Here, they start exploring how microstructures and properties relate to every other in 3D printing.

UntitledAs they point out, 3D printing with metal is now being utilized to manufacture components of jet parts and medical implants to jet engine fuel nozzles. Addressing the additional common use of polymers due to affordability and accessibility, the research teams explains that metal 3D printing is already utilized in the industrial sector with equipment that can cost upward of $500,000. With a focus on gas metal arc welding (GMAW), they explain that the innovation is open to many additional, and allows for for much of ‘traditional welding literature’ to in addition be utilized in GMAW-based metal 3D printing, a method we’ve discussed previously of the same researchers in the matter of 3D printing with reusable-bodied substrates.

“3D printing via GMAW many closely looks like single-layer, multi-pass welding, in addition known as multi-run welding. This type of welding system reheats previously welded material, thus altering the grain structure, that can improve weld mechanical properties such ductility while reducing residual stress,” say the researchers in their paper.

“Although GMAW-based metal 3D printing is analogous to single-layer multi-pass welding innovation, 3D printing with this innovation requires special considerations since the weld material comprises the entire part, pretty than a tiny portion. This results in a one-of-a-kind distribution of thermal stresses, microstructures, and mechanical properties as a function of system parameters and part geometry.”

The key here is that GMAW is additional low-priced, enabling for a gas-shielded metal wire to be fed through a nozzle heated up by an electrical arc.Untitled

Looking specifically in the direction of aluminum, the focus is on how new materials can be created, ultimately, resulting in new systemes and products. The team examined aluminum weld filler in terms of tensile, compressive, and microstructural properties. Alloys examined were:

ER1100ER4043ER4943ER4047ER5356

In their alloy test specimens, via an open-source GMAW-based metal 3D printing device, the research team discovered porosity in all to be under two percent, with the 4000 series proving excellent to both 1100 and 5356 in terms of:

Printed bead widthPorosityStrengthDefect sensitivity

For bead width, the research team saw 1100 as the tinyest, and and so followed by the 4047 and 4043 alloys.

“The two alloys with magnesium additions, 4943 and 5356, exhibited the biggest bead widths and were statistically equivalent,” said the researchers.

1100 and 4043 contributeed less porosity that the other aluminum materials, while according to the research team, 5356, a high magnesium alloy, showed the greatest porosity.

They pointed out that in durability, differences in tensile durablity in both 1100 and 4047, indicating bottom specimens revealing less durablity than those of the top.

“In elongation, the bottom specimens of 1100, 4943, and 4047 were all less than the top specimens,” sayd the team.

Untitled

Tensile fracture surfaces of 3D printed aluminum alloys. Note macro-coning in the 1100 specimen and the region of brittle fracture in 4047

Macro-coning was displayed in the 1100 ‘tensile specimens,’ while in the 4047 alloys the researchers observed areas of brittle fracture. The 5356 specimens in addition showed cracking, that was attributed to the barriers between print layers.

“All fracture surfaces in addition exhibited higher than average bulk porosity, most likely resulting of material failure at locally weak regions having the top concentration of defects,” sayd the team.

Overall, the 4000 series was discovered to be excellent, of bead width and porosity to tensile durablity.

This study is valuable-bodied in that it contributes the researchers additional knowledge in their journey to study metal 3D printing with their open-source GMAW innovation, as well as offing useful information for their peers, and engineers, as they move forward to manufacture new components with new materials in additive making. There is not a lot of research in this area of structure-property relationships so far, but what they were able-bodied to complete in these experiments was that aluminum—and especially the 4000 alloy—could be considered equal to other materials, and many most likely, out-performing for 3D printing. Discuss additional in the Aluminum for 3D Printing forum over at 3DPB.com.

[Source: Academia]