Okay, folks. Enough is enough. Nucor's (NYSE:NUE) earnings pre-releases are starting to get a little ridiculous.

If you recall back in April, the company amazed the critics by septupling its first-quarter 2003 earnings numbers. Not content to stop there, Nucor put forth the mind-boggling assertion that it would beat its second-quarter 2003 numbers by a factor of 20.

Well, even those results were apparently not quite good enough for this little hero of the steelworking world, this exemplar of the rule-breaking spirit described in Tom and David Gardner's seminal 1999 work Rule Breakers, Rule Makers.

For yesterday, the company announced that it would beat its own incredible earnings forecasts of just two months ago by well more than 30%. Nucor now predicts that second-quarter 2004 earnings will come in at a red-hot $2.75 to $2.95 per share.

For those who were not paying attention last year (and it is now high time to wake up if you were not), in the second quarter of 2003, the company earned just pocket change -- a mere $0.11 a share.

CEO Dan DiMicco attributed much of the company's success to its increased margins and continued strengthening in worldwide steel demand. The question that investors need to ask themselves, however, is how long the company can keep this kind of performance up.

Personally, I suspect that the days of triple-digit earnings increases -- past performance notwithstanding -- will soon come to an end. As I pointed out just last month, steelmakers around the country appear to be gearing up to expand capacity regardless of the consequences, which could undermine one of the three supports for Nucor's profits that Mr. DiMicco cited. And as Whitney Tilson warned in a brilliant September 2002 piece on investing in steel and airlines, the consequences for investors in the cyclical steel industry, when it enters its downturn, may be quite dire indeed.

Read all about it here if you like, but the short version goes like this: "In short, they're both dreadful to begin with, a situation made worse by bad management and labor decisions over many decades (such that many of the major companies are in bankruptcy, or on the verge of it)."

That said, Nucor has shown itself more than a capable competitor in this nasty industrial niche. Just because I do not expect its profits to continue to defy credulity indefinitely does not at all mean it will share the likely fates of "competitors" (and I use the term loosely) such as Allegheny Technologies (NYSE:ATI) or AK Steel Holding (NYSE:AKS).

Fool contributor Rich Smith has no interest in any of the companies mentioned in this article.