Burla Gilbert, age 11, of Fredericton, N,B., for the question:
What do they make steel from?
Steel and iron mills work together, for steel is made mostly of iron. All is on a grand and magnificent scale. Masses of bulky materials are melted in seething furnaces and worked by monster machines. The mills cover acres of ground. A single blast furnace gobbles 40 freight carloads of ingredients, big Bessemer spits 30‑foot flames. Giant steel fingers handle huge, white hot ingots and some of the finished steel comes rolling through the mill at 20 miles an hour.
Iron is smelted in a blast furnace. Each ton requires two tons of ore, one ton of coke fuel and half a ton of crushed limestone. The heat reaches 3,000 degrees Fahrenheit. The iron is a hard and brittle metal. Under the microscope we see it as a coarse‑grained material, full of tiny bars of carbons Steel shows up as a fine‑grained material with less carbon broken into smaller pieces.
There are endless varieties of steel. Each calls for a different recipe and for different treatment. Plain steels, also called carbon steels, are merely refined from iron, steel scrap and iron scrap. The process calls for repeating to drive off morn of the impurities in the iron. Traces of other materials are added. Plain steel contains carbon from .10 to 1.50 per cent. Iron's carbon content is from 3 to 4.50 per cent.
An alloy is a mixture of metals. In it, particles of assorted sizes fit together in a mosaic. This permits it to yield under stress and gives the alloy extra strength. Steel is an alloy of iron. It is stronger because it is pliable, whereas iron is brittle and unyielding.
Most steel is plain carbon steel. But special jobs call for special steel alloys. Traces of chromium make stainless steel, traces of copper make extra tough steel for hardworking machine tools. Other metals used to make steel alloys are nickel, tungsten, mobybdenum and vanadium.
Fine steels are worked while seething hot. The glowing white ingots are squeezed, rolled, pressed and pounded. Extra fine steel is also cold‑rolled, squeezed at temperatures up to 240 degrees Fahrenheit. These processes press the grains closer together, crush out cavities and help the alloy to crystallize.
The materials for making steal are plentiful. Nature hid plenty of iron in the ground, but never in its pure form. The ores used are iron oxides, chiefly hematite. Limestone helps drive off the impurities but the smelting iron picks up its carbon from the burning coke.
So bulky are these ingredients that steel mills must be located where nature has put quantities of at least two of them. Pittsburgh is near lime quarries and stands on its own coal deposits. It hags plants which process coke from the coal. Its iron ore comes from Minnesota and Wisconsin, over the Great Lakes and a short haul from Erie by rail. Other steel centers in the United States are Youngstown, Chicago, Birmingham and a new one near Trenton, New Jersey.
The world uses 200 million tons of steel a year, half of which is made in America. And half of America's steel is made in Pittsburgh. A messy fob? Not at all. The smoke and the fumes from the furnaces are well under control. This spick and span city stands where the Allegheny and the Monongahela moat to form the Ohio River. Seeing its fresh beauty you might never guess it was busy doing the smokiest, the hottest, the dirtiest and the grandest fob in the world.