About Steel

Basic terminology

Pig iron – an alloy of iron with carbon, produced as an output of the blast furnace. Pig iron has a high carbon content (3%-4,3%) and numerous impurities so that it is fragile and useless as a material. The name indicates that it is a raw material used for further productive step.

Cast iron – pig iron melted again with any cast iron or steel scrap and additives. Cast iron contains 2,2%-3,6% carbon.

Cast steel – multi-alloy of iron with carbon, containing less than 2% of carbon, not treated with any forming operation, intended for casting. Cast steel has much better mechanical properties than cast iron. In particular, it can be treated with forming operations. The varieties of cast steel with a carbon content below 0,25% are also well weldable.

Steel – on alloy if iron with carbon after forming operation (eg. rolling) containing less than 2% carbon.

grafika Basic terminology

Steel division

1. Structural and special steels:

  • Non-alloy structural steels
  • Alloy structrual steels
  • Corrosion-resistant steels
  • Steels for bearings
  • Steels for special applications

2. Tool steels:

  • Non-alloy tool steels
  • Alloy tool steels
  • High-speed steels

Chemical composition

A decisive influence on the properties of non-alloy steel has a carbon content. Materials made of non-alloy steel contain also certain amounts of other elements originating from the ore and metallurgical processes. Elements such as oxygen, nitrogen, sulfur and non-metallic inclusions, mainly oxides of sulfur and phosphorus are called impurities.

Other steels contain in addition to carbon such alloying elements as eg. nickel, chromium, manganese, molybdenum, vanadium, cobalt, silicon. They are added to achieve certain specific properties, eg.:

– increase the strength,
– resistance to corrosion,
– heat resistance,
– susceptibility to heat treatment.


  • Chromium in a large amount (12%-30%) significantly increases the resistance of steel to oxidizing agents, that is why it is a component of heat-resistant, acid-resistant and stainless steels.
  • Silicon reduces energy loss, therefore it is used in amounts up to 4% for production of generator and transformer sheets.
  • Molybdenum increases the depth of hardening.
Chemical composition stal

Steel markings

Determination of steel grades by application and properties
Oznaczanie gatunków stali wg składu chemicznego
Determination of steel grades according to chemical composition
Symbols describing the type of coating of steel products
Symbols denoting the state of processing of steel products