In a paper published in the Journal of Manufacturing Processes, researchers at Pacific Northwest National Laboratory (PNNL) reported that their new shear assisted processing and extrusion (ShAPE) technology (earlier article) Extrusion of aluminum alloy 7075 pipes at speeds up to 12.2 m/. No surface tear in minutes. This is the first experimental evidence of 7075 high-speed extrusion, which improves conventional extrusion with a limit of 2.0 m/min.

Although automakers have been increasing the use of aluminum in high-volume models to reduce vehicle weight—especially Ford, which began manufacturing F-150s with mainly aluminum bodies in 2014—but through the use of more advanced aluminum alloys. Components can reduce more weight such as roof rails, cross members, subframes and other structural parts. However, these alloys are expensive, partly because of their slow manufacturing speed using traditional extrusion.

The strength-to-weight ratio of 7075 aluminum alloy is 85% higher than that of typical passenger car alloys; however, compared to the commonly used 6000 series alloys, the manufacturing cost is about 30% higher.

This price difference is acceptable in aerospace applications, where lighter weight materials outweigh higher costs to achieve better fuel efficiency, improved maneuverability, and lower launch costs. But in vehicles, this is a limiting factor that we hope to change. — Scott Whalen, lead author and corresponding author

This high cost is mainly due to the difficulty of extruding 7075 alloy into structural parts. 7075 is widely regarded as the most difficult to extrude of all commercial aluminum alloys. Slow extrusion speeds of only 1 to 2 meters per minute, combined with higher energy requirements, make 7075 more expensive than 6000 series alloys that are extruded at speeds of more than 20 meters (65 feet) per minute.

PNNL's ShaAPE process uses a machine to rotate billets or bulk metal alloys to generate enough heat through friction to soften the material, so it can be easily extruded through a die to form tubes, rods and channels. At the same time, the linear and rotational forces use only 10% of the force required to push the material through the mold in the traditional process.

This significant reduction in force greatly reduces the size of the production machinery, thereby reducing capital expenditures and operating costs. Energy consumption is also low. The amount of electricity used to make a 1-foot-long, 2-inch-diameter pipe is about the same as the amount of electricity required to run a home kitchen oven for only 60 seconds.

The microstructure grains of the material produced by this process are much finer than the grains of the material before extrusion. These finer grains and their orientation are generally uniform throughout the product, thereby providing greater strength and ductility. For example, the room temperature ductility measured independently exceeds 25%, which is a great improvement compared to typical extrusions. Preliminary studies have shown that this process also greatly improves the energy absorption of the metal.

ShaAPE can extrude pipes, wires and rods whose strength characteristics meet important industrial ASTM standards and typical values ​​of ASM. The elongation of 7075 alloy is 50% higher than that of traditional extrusion, which helps to absorb energy during collision.

In addition to increasing speed, the ShaAPE process can also eliminate the energy-intensive heat treatment steps required in traditional extrusion, saving approximately 50% of the energy required to extrude alloy 7075.

Using the traditional extrusion process, large metal billets must first be heat treated at temperatures exceeding 400 °C (750 °F) for approximately one day to distribute different elements such as magnesium and copper evenly throughout the alloy. ShaAPE is able to extrude blanks under non-homogeneous conditions and is estimated to save 5% on the total cost of ShaAPE extruded products.

In addition, in conventional extrusion, preheating in a furnace is required to soften the billet before extrusion. With ShAPE, no preheating is required because all the necessary heat comes from the process itself. Other post-extrusion heat treatments have also been eliminated or reduced, resulting in an overall energy saving of 50%.

ShaAPE increases the extrusion speed while reducing energy consumption, thereby reducing carbon emissions, making the lightweight 7075 alloy cost-effective in the passenger car market. By improving the fuel efficiency of internal-combustion-powered cars and extending the range of electric vehicles per charge, lighter vehicles will ultimately help reduce carbon emissions in the transportation sector.

Scott Whalen, Matthew Olszta, Reza-E-Rabby, MD, Timothy Roosendaal, Tianhao Wang, Darrell Herling, Brandon Scott Taysom, Sarah Suffield, Nicole Overman (2021) "High-speed manufacturing of 7075 aluminum alloy through shear-assisted processing and extrusion Pipe (ShaAPE), Journal of Manufacturing Processes, Volume 71, Pages 699-710, doi: 10.1016/j.jmapro.2021.10.003.

Published on October 27, 2021 in Manufacturing, Market Background, Materials, Weight Loss | Permalink | Comments (1)

Sounds great-lighter, stronger, cheaper (!) Hope they can launch it, otherwise it is just an interesting paper.

Posted by mahonj | October 27, 2021 at 07:29 AM

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