Pig iron
Foundry pig iron is used for further production of moldings in foundry shops.Pig iron
Pig iron is multi-component alloy of iron and carbon (>2.14%), silicon, manganese, phosphorus and sulphur. Depending on iron’s designation and composition of burden, it may contain chrome, nickel, vanadium, titanium, cuprum and arsenic.
All blast-furnace irons according to their designation can be divided into two groups:
Open-hearth pig iron – designated for further production of steel.
Foundry pig iron – after remelting is used for moulding and as an additive in steel-making and foundry industries.
Open-hearth iron is the predominant type of product of foundry manufacture. It posses 90% of all produced pig iron.
It is designated for steelmaking in converters or open-hearth furnaces and usually contains 0,3-1,2 % Si; 0,2-1,0 % Ìn, 0,15-0,2 % Ð and 0,02-0,07 % S.
Each class of foundry irons (LK) consists of six grades. The most siliceous is iron of grade LK0 containing 3,26-3,75 % Si.
Each following grade contains 0.5% less of silicon.
More over each group is divided into three groups according to manganese content (0,5; 0,51-0,90 and 0,91-1,3%) and into three categories according to sulfur contentè (0,02-0,05; 0,03-0,06 and 0,04-0,07 %).
Depending on chemical composition and speed of cooling the crystallization of iron finishes in formation of white, mottle or grey pig iron.
White pig iron contains cementite and pearlite and has white rupture. It is very hard and wear-resistant but at this it is very friable and hard-processing.
Mottle contains pearlite, cementite and some impurities of graphite, in form of lamellar particles
Grey pig iron is characterised by containing considerable quantity of graphite impurities of lamellar or spherical form.