01 of 05

Mini Mill

“As has been the case since our company was founded nearly five decades ago,
Nucor’s teammates – the right people – are our company’s strength and our greatest competitive advantage.”

Nucor may not have an official R&D department, but there are few that can match our record of technological firsts. It starts with the Mini Mill...

mini mill

Nucor pioneered and popularized the mini mill. Currently these facilities, which rely
on scrap metal as their main raw material source, account for about 60%
of U.S. steel production.

Prior to the mini mill, steel was made by integrated steel producers in energy-intensive
blast furnaces. Nucor began a new era in American steel making in 1969, when our
first mini mill went into production. Originally it was simply a way to supply
Vulcraft, our construction joist division. Soon, word spread,
and this economical, reliable method of steelmaking
became in high demand by outside customers.
We’ve been expanding ever since.

Caution Hot Surface
Electric Arc Furnace

Electric Arc

Nucor’s Electric Arc Furnace drives the mini mill process. A 90-to-150 megawatt powerhouse, it can transform 130 – 170 tons of scrap and iron into liquid steel in the time it takes to bake a chocolate cake.

Holding the equivalent of several crushed cars worth of scrap, each 3,000-degree behemoth contains giant carbon electrodes that cast an electric arc to melt the scrap, creating a constant source of molten steel. Nucor’s EAFs allow us to recycle an average of 1,200 pounds of steel every second of every hour of every day.

“In an old cornfield in Crawfordsville, Indiana, in America’s Rust Belt, a maverick company called Nucor is attempting nothing less than THE resurrection of the American dream.”

— From “American Steel,” by Richard Preston


Nucor holds numerous distinctions in the history of U.S. steelmaking. Crawfordsville has two: the location of the first mini mill to produce flat-rolled steel and the birthplace of thin-slab casting, perhaps our most famous gamble.

Fast forward to 1987. We announced we would cast 2-inch slabs, 4 to 5 times thinner than industry standard, which meant no more roughing mill, a labor-intensive thinning process for thicker flat-rolled steel. This drew instant skepticism, with one rival circulating an inch-thick report explaining why thin-slab casting would never work.

Fifteen-plus years later, thin-slab is used in manufacturing plants around the world and accounts for a huge portion of the flat-rolled steel made in America.

micro mill

Nucor innovation also means our thin-strip casting technology — Castrip®. Produced in the world’s first micro mill, right next to — appropriately enough — our Crawfordsville mini mill, this single-step process converts molten steel directly into solid sheets, greatly minimizing energy use and time and maximizing space and manpower.

Long term, our goal is to produce Castrip as fine as 0.028 in. (0.7 mm) for exciting opportunities in structural decking, purlins and light-gauge steel framing, as well as for tubular goods and structural applications like racking.

Another Nucor revolution for the industry, the commercial success of Castrip has led to a second facility in Arkansas.

Thin-Strip Casting
Thin-Slab Casting
Conventional Slab Casting
Energy and Emissions Comparison