Introduction
Iron and its alloys is the most widely used material used in mechanical engineering. This page include notes on the different methods used to produce the metal from the raw materials.

General

Pig Iron and recycled scrap metal is the basic feedstock to all the iron steel making processes. Pig Iron is generally produced continuously in blast furnaces from a feedstock of iron ore, coke, lime etc. The resulting pig iron is impure with a carbon content at about 4% and up to 4% total of silicon, manganese, phosphorous and sulphur. The pig iron and scrap are used to produce Cast Iron, and Steel

Cast Iron production is relatively unsophisticated. It mostly involves remelting charges consisting of pig iron, steel scrap, foundry scrap, and ferro-alloys to give the appropriate composition. The cupola, which resembles a small blast furnace, is the most common melting unit. Cold pig iron and scrap are charged from the top onto a bed of hot coke through which air is blown. Alternatively, a metallic charge is melted in a coreless induction furnace or in a small electric-arc furnace. The resulting types of Cast Iron are described below;

Grey Cast Iron
BS 1452:1990 : "Specification for Flake Graphite:"... UTS 170-370 MPa, Elongation- 0.5-0.8%
Has structure ferrite, pearlite and graphite. The graphite can exist as flakes or spheres.

Nodular Ferritic
BS 2789:1985 : "Specification for spheroidal graphite or nodular graphite CI:" ... UTS 350-480 MPa, Elongation-6-16%...
Nodular Cast Iron is obtained by adding magnesium which encourages the graphite to form spheres or nodules.

White Cast Iron/Nodular Pearlitic
BS 2789:1985 : "Specification for spheroidal graphite or nodular graphite CI:"...UTS 600-800 MPa, Elongation 2-3%...
Has a structure of cementite and pearlite making it hard, brittle and difficult to machine. It is used for wear resisting components. Fracture surfaces have light-coloured appearance.

Malleable Cast Iron..
BS 6681:1986: "Specification for Malleable CI;"
Heat treated forms of white CI to improve ductility while maintaining the benefits of of high tensile strength ;

Three Types Available;

1. Whiteheart..UTS 250-400 MPa, Elongation 4-10%...
   this is heat treated with and iron compound to give an outer ferrite layer and a ferrite/pearlite core...

2. Blackheart...UTS 290-340 MPa, Elongation 6-12%...
   Soaked at high temperature to cause the cementite to break down, then slowly cooled to give ferrite and graphite

3. Pearlite... UTS=450-550 MPa, Elongation 6-12%...
   Similar to blackheart but faster cooling to produce a pearlite structure with higher strength

Wrought Iron is no longer produced in commercial quantities, the wrought iron that survives contains less than 0.035 percent carbon. It therefore consists essentially of ferrite, but its strength and malleability are reduced by entrained puddling slag, which is elongated into stringers by rolling. As a result, breaking a bar of wrought iron reveals a fibrous fracture not unlike that of wood. The other elements present are silicon (0.075 to 0.15 percent), sulfur (0.01 to 0.2 percent), phosphorus (0.1 to 0.25 percent), and manganese (0.05 to 0.1 percent). This relative purity is the reason why wrought iron has a reputation for good corrosion resistance.

Steel is by definition an alloy of iron and carbon in which the carbon content ranges up to 2 percent (with a higher carbon content, the material is defined as cast iron). By far the most widely used material for building the world's infrastructure and industries, it is used to fabricate everything from pins to oil tankers. The main reasons for the popularity of steel are the relatively low cost of making, forming, and processing it, the abundance of its two raw materials (iron ore and scrap), and its unparalleled range of mechanical properties.

Cast Carbon Steels..

BS 3100:1984 "Specification for steel castings for general engineering purposes:"
BS1504:1984 "Specification for steel castings for pressure purposes"
*****To be continued*******