As viewers of HBO's mini-series Rome will know, emperors from Julius Caesar onwards sought to resist delusions of grandeur by employing a slave to whisper in their ear, "Remember you are mortal." Amid the pomp and circumstance of what many people now acknowledge to be the most sustainable period of growth in the steel market for a generation, a similar warning would be advisable.

The steel industry may not be the new Rome—although reports of its decline and fall have proven to be greatly exaggerated—and today's executives would be the first to warn of continuing threats to the current era of growth, but for an industry that less than 10 years ago had to...