Researchers say they’ve made a new “super steel” that challenges conventional wisdom about new steel alloys. Instead of the usual fine-tuned balance of tradeoffs, scientists at the University of Hong Kong and Lawrence Berkeley National Labs say their super steel mitigates the catch-22s in many previous alloys. The secret is in how the molecular structure of the steel works to absorb and nullify stress damage.

These researchers have introduced delamination toughening into their steel. Let’s break down a complex idea piece by piece—or layer by layer, more appropriately.

Many kinds of steel (and materials in general!) are laminated, in the sense of the word invoked by layered flaky pastries like croissants or baklava. Even the mechanisms are surprisingly similar: Steel can be milled by heating and then rolling it to desired thickness, and those layers accumulate by rolling or folding.

MORE FROM POPULAR MECHANICS

Can You Build The Farmer’s Fence?Video Player is loading.UnmuteCurrent Time 0:00Loaded: 23.18%Remaining Time -1:19CaptionsFullscreen

When steel is under strain, it shows one of several modes of failure. One of these is delamination, where a previously uniform piece of subtly layered steel fractures into separate layers due to structural stress. It’s kind of like the way a violin bow begins to fray, going from one smooth surface of horsehair to individual hairs that break and spring loose.

But delamination can itself trigger a strengthening mechanism within steel and other materials. This careful design is delamination toughening. The National Institute of Materials Science’s Tadanobu Inoue wrote in a 2016 textbook:

“The extension of delamination is characterized by the ductility of the next layer, where a new crack is renucleated. This pattern is repeated until the sample is fully fractured. Therefore, for delamination toughening, it is important to have not only a weak interface but also a layer with plastic deformation abilities.”

In other words, one large crack can quickly travel through all the layers of a piece of steel, but laminated steel is in a unique position to halt them. With the right engineering of the entire piece, the cracking burden is distributed evenly and the steel remains strong. It’s this idea that makes the new “super steel” so strong.

“[F]racture under plane-strain conditions is automatically transformed into a series of fracture processes in ‘parallel’ plane-stress conditions through the thickness,” the scientists explain in the new paper.

And how did they do it? Following Inoue’s 2016 description, the super steel relies on plasticity. “We show that improved fracture resistance in a steel with an ultrahigh yield strength of nearly 2 [gigapascals] can be achieved by activating delamination toughening coupled with transformation induced plasticity.” It’s made from a specially structured alloy containing manganese.

Most shocking, though, could be the cost. “The team says this makes the super steel stronger and tougher than the Grade 300 maraging steel used in aerospace engineering,” the University of Hong Kong said in a statement. “[A]nd the new steel only costs about 20 percent of the price to manufacture.”