Ferrous & Alloy steel Material Selection & understanding of AISI Standards

Ferrous metals

Ferrous Metals: Iron is the principal constituent of these ferrous metals. Ferrous alloys contain significant amount of non-ferrous metals. Ferrous alloys are extremely important for engineering purposes. On the basis of the percentage of carbon and their alloying elements present, these can be classified into following groups

(a) Mild or Low carbon Steels : The percentage of carbon in these materials range from 0.15 % to 0.25 %. These are moderately strong and have good weldability.

The production cost of these materials is also low.

(b) Medium Carbon Steels: These contains carbon between 0.3 % to 0.6 %. The strength of these materials is high but their weldability is comparatively less.

(c) High Carbon Steels: These contains carbon varying from 0.65 % to 1.5 %. These materials get hard and tough by heat treatment and their weldability is poor. The steel formed in which carbon content is up to 1.5 %, silica up to 0.5%, and manganese up to 1.5 % along with traces of other elements is called plain carbon steel.

(d) Cast Irons: The carbon content in these substances vary between 2 % to 4%. The cost of production of these substances is quite low and these are used as ferrous casting alloys

s and the terms refer to a family of alloys including gray cast iron, ductile iron, white and malleable iron.

(e) Alloyed Metals: Alloys can be formed by blending two or more metals or at least one being metal. The properties of an alloy can be totally different from its constituent substances, e.g. 18- 8 stainless steel, which contains 18 %, chromium and 8 % nickel, in low carbon steel, carbon is less than 0.15 % and this is extremely tough, exceedingly ductile and highly resistant to corrosion