When mini-mills such as Nucor Corp. and later Steel Dynamics Inc. (SDI) established the viability of electric-arc furnace steelmaking in the U.S., they overturned a few sacred cows in the process. Traditional producers had to change their game, while the knock-on impact of their strategy helped refashion the way steel was produced.

Over the past few months, the next phase of the two companies' business strategy has become clear. And after watching with some trepidation as Nucor and SDI paid billions of dollars to buy David J. Joseph Co. and OmniSource Corp., respectively, many scrap executives are asking themselves: are changes of the same magnitude now taking place in their own industry?

Consolidation in scrap isn't a new phenomenon, of course, and was underway well before Nucor and SDI piled into the market. The merger of Metal Management Inc. with Australia's Sims Group set the tone for...