The Effects of Straining Structural Steel and Wrought Iron

Iron, in combination and mixture with small proportions of carbon and other substances, and variously treated in its manufacture, is produced for commercial purposes in many varieties, which differ greatly in strength and ductility but little as regards the rate at which, within the elastic limit, dimensions and bulk are changed by straining at ordinary atmospheric temperatures. One variety, made by welding plastic masses which contain very little carbon and some slag, is termed wrought iron. This is a ductile variety, comparatively low in strength. Most of the other varieties are known as steel. One now little used variety of steel, slag-bearing or weld steel, is made from wrought iron by heating and adding carbon, but without remelting. The other varieties of steel are slagless and, when not simply cast, are made from steel castings (termed ingots) by mechanical and thermal treatment. The different varieties of steel cover a large range of strength, ductility, and hardness, the comparatively soft varieties being more ductile than wrought iron, and the very softest being slightly weaker.