TABLE OF CONTENTS Iron was produced by primitive man by placing iron ore and charcoal in a clay pot and building a fire in the pot, using a crude bellows to provide the forced draft that deposited iron at the bottom. It was not until the mid-1800s that Henry Bessemer, an English metallurgist, developed a process whereby forced air was introduced into the iron-refining procedure raising the temperature of the crucible so that impurities in the molten pig iron were burned away In the process, a more malleable metal, steel, was created.
Various minerals and metals are added to molten steel nowadays to enhance certain characteristics:
Nickel Improves the hardenability of steel and increases impact strength at low temperatures.
Sulfur Increases machinability.
Manganese Increases strength and hardness.
Carbon The principal hardening agent in steel.
Molydenum Prevents brittleness.
Vanadium Gives steel a fine grain structure and improves the fatigue values.
Silicon Improves strength. It is a deoxidizer.
Phosphorous Improves the machinability of high-sulfur steel sand imparts some resistance to corrosion.
| ASTM designation | Steel type |
|---|---|
| A36 | Carbon |
| A529 | Carbon |
| A441 | High strength (low alloy) |
| A572 grade (includes 42, 50, 60, 65) | High strength (low alloy) |
| A242 | Corrosion resistant, high strength Low alloy |
| A588 | Corrosion resistant, high strength Low alloy |
| A852 | Quenched and tempered (low alloy) (Plates only) |
| A514 | Quenched and tempered alloy (Plates only) |
During the last decade...
