THERE'S rarely been a better time to be in the steel business. Prices have boomed worldwide this year, smashing record after record.... Manufacturers such as Nucor Corp., U.S. Steel Corp. and SSAB AB are among those set to become profit machines.... ArcelorMittal SA, the world’s biggest outside of China, will earn more than McDonald’s Corp.or PepsiCo Inc., according to analysts’ estimates. Few expect these good times to last through 2022....