Iron Castings Terminology
 

Austenitize - to convert the matrix of a ferrous alloy to austenite by heating above the transformation temperature.

Batch - the component raw materials properly weighed, proportioned, and mixed for delivery to a processing unit. Also, the product output from a processing unit in which there is essentially no product output until all component materials are charged and processed.
Carbide, primary - carbide precipitated in cast iron during solidification.

Cast iron - a generic term for a series of alloys primarily of iron, carbon, and silicon in which the carbon I in excess of the amount which can be retained in solid solution in austenite at the eutectic temperature.

Cementite - a very hard and brittle compound of iron and carbon corresponding to the empirical formula Fe3C, commonly known as iron carbide.
Cementite, primary - cementite precipitated in cast iron during solidification. Also known as primary carbide.

Chilled iron - a cast iron that would normally solidify as a gray cast iron which is purposely caused to solidify as white cast iron locally or entirely by accelerated cooling caused by contact with a metal surface, that is, a chill.

Direct reduced iron - iron ores that have been reduced to essentially metallic iron by heat and reducing agents, but without melting, and processed into suitable shapes for use as a charge material in a melting operation.

Dual metal - two metals of different composition that are fusion bonded at all interfacial surfaces by casting metal of one composition against metal of a second composition.

Ductile iron - a cast iron that has been treated in the liquid state so as to cause substantially all of its graphitic carbon to occur as spheroids or nodules in the as-cast condition.

Ferritize - to increase the quantity of ferrite in the matrix of a ferrous casting through an appropriate heat treatment.

Ferritizing anneal - the process of producing a predominantly ferritic matrix in cast iron through an appropriate heat treatment.

Graphite, compacted - a graphite shape that is intermediate between flake graphite and nodular graphite that typically appears in a polished section as thick flakes with blunt ends.

Graphite, flake - an irregularly shaped particle of graphite, usually appearing in a polished section as curved plates, such as found in gray cast irons.

Graphite, nodular - spheroidal shaped graphite typically found in ductile irons and compact clusters of graphite typically found in malleable irons.

Graphite, primary - graphite precipitated in cast iron during solidification.

Graphite rosette - arrangement of graphite flakes in which the flakes extend radially from centers of crystallization in gray cast iron.

Graphite, spheroidal - spheroidal shaped graphite having a polycrystalline radial structure, usually found in ductile iron and to a controlled, limited extent in compacted graphite iron.

Graphitize - to precipitate graphite in an iron-carbon alloy.

Gray iron - cast iron that has a relatively large proportion of the graphitic carbon present in the form of flake graphite. The metal has a gray fracture.

Heat - the total molten metal output from a single heating in a batch melting process or the total metal output from essentially a single heating in a continuous melting operation using basically constant charge and processing conditions and targeted at a fixed metal chemistry at the furnace spout. A heat can also be defined as a fixed time period for a continuous melting operation provided that it is shorter than the time period covered by the above definition.

Inoculating alloy - an alloy added to molten iron for the principle purpose of nucleating a primary phase such as graphite. Inoculating alloys are frequently used to avoid the formation of primary carbide by enhancing the nucleation of graphite.

Malleable, ferritic - a ferrous alloy that is cast as white is converted by an appropriate heat treatment to a microstructure of temper carbon embedded in a ferritic matrix essentially free of pearlite and carbide.

Malleable iron - a cast iron of such composition that it solidifies as white iron, which upon proper heat treatment is converted to a metallic matrix with nodules of temper carbon.

Malleable, pearlitic - a ferrous alloy that is cast as white iron but which is converted by an appropriate heat treatment to a microstructure of temper carbon embedded in a matrix containing a controlled quantity, form, and distribution of pearlite or tempered martensite.

Malleableize - to convert white iron into malleable iron through an appropriate graphitizing heat treatment.

Melt - the total molten metal produced in a single heat.

Merchant pig iron - pig iron produced for commercial sale to foundries.

Mottled iron - a cast iron containing a mixed structure of gray iron and white iron of variable proportions. The fracture has a mottled appearance.

Nodular graphite - graphite in the form of nodules or spheroids in iron castings.

Nodularity - the volumetric proportion of spheroidal or nodular graphite to total graphite in a ductile iron or a compacted graphite iron matrix.
Nodularity, degree of - the volumetric proportion of spheroidal or nodular graphite to total graphite in a ductile iron matrix.

Nodulizing alloy - an alloy added to molten iron for the primary purpose of causing the formation of spheroidal graphite during solidification.

Pig iron - the high carbon iron product obtained by the reduction of iron ores, typically in a blast furnace or an electric furnace, and cast into uniform shapes having physical and chemical characteristics suitable for end as foundry melting stock.

Sample - one or more portions of a liquid or solid material taken in an unbiased manner from a batch, heat, lot or process stream to be representative of the whole, for subsequent testing to determine the chemical, physical, mechanical, or other quality characteristics of the material, or combination thereof.

Temper carbon - compact aggregates or nodules of graphite found in malleable iron as a result of heat treatment.

Test bar - a bar-shaped coupon that is tested with or without subsequent preparation for the determination of physical or mechanical properties.

Test coupon - specially designed casting, or portion thereof, that is used to provide a representative sample of the iron from which it was cast.

Test lug - a sample produced as an appendage on a casting, that may be removed and tested to qualify the casting or the iron which it was produced.

Test specimen - a test object, suitably prepared from a sample, for evaluation of the chemical, physical, mechanical, or metallurgical quality of the sample.

Treated iron - molten cast iron to which all basic alloys and nodulizing alloys have been added but not necessarily all inoculating alloy additions.

White iron - cast iron in which substantially all of the carbon is in solution and in the combined form. The metal has a white fracture.