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Jun 28, 2023

Metal is King for a Sustainable (and Profitable) Future

James D. Blythe Follow -- Listen Share From the desk of James Blythe — Okay listeners, get out your thickest coke-bottle glasses and pocket protectors. Let’s talk some material science to kick off

James D. Blythe

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From the desk of James Blythe —

Okay listeners, get out your thickest coke-bottle glasses and pocket protectors. Let’s talk some material science to kick off your week.

For a very long time, metallurgy (the science of metals and metal alloys) has been not particularly sexy. “Gee wiz Mr. Blythe, haven’t we discovered all the metals there are? What could be left? We still make everything out of steel, how boring! Did you hear about this latest graphene-nano-dot-micro-tube-composite-thing?” I can understand this feeling.

Yet in a world of super materials, metal is supreme.

When a job absolutely positively must get done, you call metals. When a building must be built or a car structure must be fabricated, you call metals. If you need strength and durability and workability, you call metals.

New metal alloys are being invented all the time. A few less points of carbon here, a few more points of scandium there, that sort of thing. The big breakthroughs in metallurgy, however, have not been as eye-catching or earth-shaking as they might have been in the 1960s. What has lagged behind, however, is not the research and development of new alloys, but the implementation and adoption of existing ones. Worse, American infrastructure to support these critical materials has continuously slumped under economic pressures from Asia and aging infrastructure.

Sure, it’s not as punchy as a headline for Popular Mechanics as “Scientists Invent Unobtanium! Cheaper than Toilet Paper, Stronger than Steel!” But it’s so much more important to our real-world future.

People bemoan modern society’s fixation on plastics, but there is a reason these engineering materials are so proliferate in commodity goods. Yet in a circular, sustainable economy plastics and composites have a hard time finding a good place to live. In a circle economy, we need to be thinking about end-of-life for our devices. When a product or device becomes obsolete, how do we reprocess or reuse it? For reprocessing plastics and composites, your options are limited (if you have any at all).

So what’s next on the horizon?

Light alloys like aluminum and titanium are the future. These hardcore manufacturing materials aren’t new, but are often overlooked in favor of common steel products. Metals are infinitely recyclable and as more companies embrace new design approaches, there’s potential for these alloys to lead us to a more profitable and sustainable future.

The major barrier? Cost and reliance on foreign exports. Let’s discuss, shall we?

You hardcore metallurgists out there have probably heard this before. For those of you who are uninitiated, you probably have no idea what I’m talking about.

In construction and fabrication and many other industries, there has been a long history of engineers and scientists discounting what is “new”. As such, many fabricator and designers and job shops still believe that old fashioned structural steel is king and that every other metal out there is unworkable.

It’s wrong, but I understand the sentiment.

Steel powers much of our industrial world. It dominates transportation and construction industries as the material-of-choice. Strong, cheap, readily available, and highly workable; these are the trademarks of good steel products. It’s also heavy.

Weight reduces fuel efficiency and places significant limits on automotive performance. Parts wear faster and need replacing more often.

In construction industries steel is used to reinforce concrete, provide structural framing, and is even fashioned into light-weight skins for weather proofing. By some estimates, steel usage in construction is excessive — on the basis of engineering design — to capture savings in labor or additional safety factor. [1] This means excess weight and waste in production. New techniques are being developed to reduce this weight.

Construction isn’t the only industry reexamining their use of steel productsion. In automotive engineers constantly work toward higher alloy, lighter weight steel products. Working to utilize them more efficiently to reduce weight and cost.

Despite concerns about the impact of heavy fabrication on the environment, recycling rates for steel range from 70% — 90% depending on who you ask. That’s a win for sustainability. That’s a win for higher productivity and cost reduction (ability to sell-back scrap and waste product).

The problem with steel is that it’s heavy and it rusts. You can’t reprocess rust easily. Thus, over time, your car or sea wall or chain link fence returns to the earth. From dust it came and to dust it shall return.

Corrosion slowly degrades critical components which can lead to unexpected failures and decrease overall service life of the product. Finding materials that are lightweight and resist corrosion better is always good.

In the end, we love steel. The problem with steel alloys is that — despite their numerous manufacturing benefits — they represent significant lifecycle issues for fabricated products. Whether they are planes, trains, or automobiles, steel is weight. Weight drags on fuel efficiency. Weight is hard on wear parts. Couple this with steel’s poor corrosion resistance and you’re replacing essential components more often than you should be.

That’s money lost. That’s excessive waste. So how do we fix it?

Do you ever hear, “new material X is stronger than steel”? Anytime you see an article with that heading, read the fine print. Often they are not actually stronger but rather are stronger within a certain context. Here’s an example. Table 1 has three common metals — A36 structural steel, 5083 aluminum, and Ti-6Al-4V (titanium) — and we are looking at some of their basic material properties; density (related to weight), yield strength (defines how much load the material can take before plastically deforming), and ultimate tensile strength (defines how much load the material can take before breaking).

Often times I see marketing materials that say “aerospace grade aluminum! Stronger than steel!” Based on this graph, there is no way that can be true. Also, keep in mind I’m using an example of very common, low strength, low alloy steel here. There are types of steel which blow these properties out of the water and even rival titanium on the chart.

However, what we’re actually showing here is that these are roughly the expected performance for bars at the same thickness (general size). So, you can see that even though aluminum has lower strength it is also lighter. Significantly so. But what if we were able to change the design of a part to accomadate the unique characteristics of lightweight alloys? Let’s see how bars of the same weight would perform.

Now we’re cooking with oil.

You can see that — for the same weight of material — both titanium and aluminum blow steel out of the water. Interesting isn’t it? Effectively, for the same amount of weight, I can have an aluminum bar that is almost 3X as thick as the equivalent steel. At that size, there are significant performance benefits. One can image then that by playing with the geometry of a part in design you can tune the performance with appropriate use of light alloys.

This is the key to enabling lighter, more sustainable, fabricated products from automotive to construction. Even better, aluminum and titanium are extremely corrosion resistant.

Tesla gets it. Over the past few years, other automotive companies have started to get it too. There’s some good thinking that’s gone into this change. Certainly, as more companies embrace use of these light weight materials, there will be a learning curve in manufacturing, but ultimately the benefits of success will be significant.

Another thing to note. It’s not shown here but the stiffness of a a member is related to the cube of its thickness. As a result, for truly rigid structures, aluminum is one of the best material selections you can make in the metallics world — assuming you can design for the thicker members.

Thick, easy to machine sections can save you a lot of pain and headache during fabrication where thing, wavy, steel members may need extra fixturing and distortion control.

America is actually really good at understanding the design and usage trade-off between these light metals and conventional steel products. It is known that lighter structures in transportation and other industries equates to fuel savings. That’s a more sustainable product. That’s lower costs for service providers. Aviation factors this trade-off into their design and procurement strategies and have numbers for “what we’re willing to pay per pound of weight saved.” This is a big reason why you see so much aluminum and titanium used in planes and rockets.

Other industries are not as well equipped. Developing that understanding is key to winning more engineers and manufacturers to the use of lightweight metals.

There are thinkers within the Army that understand the use of lightweight metals is a serious consideration for national security. Most, however, are slow to adopt this systems-scale thinking.

America makes use of a lot of aluminum and titanium. [2] The problem is that we are net importers of these materials. Guess who makes the majority of these lightweight metals? China and Russia. Aluminum production in the United States has been crushed in recent years despite record high usage. Similarly, with the war in Ukraine, titanium supply has constricted to the rest of the world with Japan working to make up the difference. This isn’t sustainable in a future likely to be driven by lighter weight metals.

Iperion X believes they can solve the U.S.’s titanium woes with their new venture in Tennessee. Right now, there doesn’t seem to be much in the works to address aluminum production domestically, but the potential exists for the U.S. to become a world-leader with the right investments. When the country decides to undertake this task, it will need to give some serious thought about the “right way” to implement. One of the challenges is that countries like China are able to harness massive stores of human capital with questionable ethical practices to get cheap and abundant product. The U.S. will have to consider how it will answer this challenge in a more sustainable way.

Given the infinite recyclability of these resources, domestic use and production of titanium and aluminum has the potential to get us closer to a sustainable, circular economy if properly utilized.

The only question left is, “how do we get there?” Smarter minds than I will be needed to answer that question in the years to come. The potential for light metal production in the U.S. has the potential to change engineered products and markets for the better. Especially for those who can sieze the opportunity.

Good hunting.

[1] The referenced article is actually an investigation into reduction of steel usage in buildings as a way to reduce carbon emissions needed to produce said material. It also contains some useful factoids about steel usage and general design principals which seem relevant background for the reader.

[2] It’s important to note that, by far, the number 1 usage of titanium materials is titanium oxide — a ceramic utilized to make pigmentation for white coloring in paints and other coatings — not as a lightweight structural metal.