Alloying elements and their influence on properties of steel...

   Alloying elements and their influence on properties of steel Steel is the most commonly used alloy of iron. The typical influence on the property of steel by the presence of alloying elements is depicted in Fig 1.         Fig 1 Effect of alloying element on steel  The following gives an overview of some of the influences of alloying elements on the properties of steel. Aluminium (Al) – It is used as a deoxidizer.  Aluminium restricts austenite grain growth in reheated steels and is normally added to control grain size.  Aluminium is very effective alloying element in controlling grain growth prior to quenching.  It is an alloying element in nitriding steels. Boron (B) – It is added to fully killed steel to improve hardenability. Boron treated steels are produced with boron in a range of 0.0005% to 0.003%. Whenever boron is substituted in part for other alloys, it should be done only with hardenability in mind because the lowered alloy content may be harmful for some applications. Boron is a potent alloying element in steel. Boron is most effective in lower carbon steels. Carbon (C) – It has a major effect on the properties of steel. Carbon is the primary hardening element in steel.  Hardness and tensile strength increases with the increase in carbon content up to about 0.85% C. Ductility and weldability of steel decrease with increasing per cent of carbon. Chromium (Cr) – It is commonly added to steel to increase corrosion resistance and oxidation resistance. It increases hardenability and improves high temperature strength.  With added carbon it gives wear and abrasion resistance properties to steels. As a hardening element, chromium is normally used with a toughening element such as nickel for superior mechanical properties. Chromium is a strong carbide former element....