Steel 2
An iron base alloy, malleable in some temperature range as initially cast, containing maganease, usually carbon, and often other alloying elements. In carbon steel and low alloy steel, the maximum carbon is about 2.0%; in high alloy steel, about 2.5%. The dividing line between low alloy and high alloy steels is generally regarded as being at about 5% metallic alloying elements. Steel is to be differentiated from two general classes of irons: the cast irons, on the high carbon side, and the relatively pure irons such as ingot iron, carbonyl iron, and electrolytic iron, on the low carbon side. In some steels containing extremely low carbon, the maganese content is the principal differentiating factor, steel usually containing at least 0.25%; ingot iron contains considerably less.