Structural sections on which the flanges are tapered and are typically not as long as the flanges on wide-flange beams. The flanges are thicker at the cross sections and thinner at the toes of the flanges.

Inside Diameter (of coil or pipe).

Immersed Scanning
In ultrasonic, a planned, systematic movement of the beam relative to the object being inspected, the search unit being coupled to this object through a column of liquid. In most cases the object and the search unit are submerged in water.

Impact Energy (Impact Value)
The amount of energy required to fracture a material, usually measured by means of an Izod or Charpy test. The type of specimen and testing conditions affect the values and therefore should be specified.

Impact Test
Test designed to determine the resistance of metal to breakage by impact, usually by concentrating the applied stress to a notched specimen.

Elements or compounds whose presence in a material is undesired.

Included angle
The angle between the planes of the fusion faces of parts to be welded.

A nonmetallic material in a solid metallic martial
Slag or other foreign matter entrapped during welding. The defect is usually more irregular in shape than a gas pore.

Inclusion Shape Control
The use of rare earth metals or calcium alloys to control the morphology of inclusions, in order to provide improved mechanical properties for select applications.

Incomplete root penetration
Failure of weld metal to extend into the root of a joint.
Incompletely filled groove
A continuous or intermittent channel in the surface of a weld, running along its length, due to insufficient weld metal. The channel may be along the centre or along one or both edges of the weld.
Indentation Hardness
The resistance of a material to indentation. This is the usual type of hardness test, in which a pointed or rounded indenter is pressed into a surface under a substantially static load.

Induction Hardening
A process of hardening a ferrous alloy by heating it above the transformation range by means of electrical induction, and then cooling as required. Quench hardening in which the heat is generated by electrical induction.

Induction Heating
A process of heating by electrical induction.
Inert-Gas Shielded-Arc Welding
Arc welding in an inert gas such as argon or helium.

Intercoat Adhesion
The adherence which is observed between the primer and topcoat of a paint system.
Between crystals, or between grains. Same as intergranular.
Intermittent weld
A series of welds at intervals along a joint.
Internal Oxidation
Formation of oxides beneath the surface of a metal.
Interrupted Aging
The aging of an alloy at two or more temperatures by steps, and cooling to room temperature after each step.

A form of semi-finished steel. Liquid steel is teemed (poured) into molds, where it slowly solidifies. Once the steel is solid, the mold is stripped, and the 25- to 30-ton ingots are then ready for subsequent rolling or forging.

Ingot casting
A technique for solidifying molten steel by pouring it into cast iron ingot molds.

Ingot Iron
Commercially pure open-hearth iron.

A substance which retards some specific chemical reaction. Pickling inhibitors retard the sis solution of metal without hindering the removal of scale from steel.


  • WHAT
    Inmetco is a coal-based process similar to FASTMET that uses iron oxide fines and pulverized coal to produce a scrap substitute. Mill scale and flue dust, inexpensive byproducts of steelmaking, can be mixed with the iron oxide fines. Inmetco, unlike other direct reduction products, is intended to be hot charged into an EAF, with attendant energy savings.
  • HOW
    The process includes three steps. First, iron oxide fines, pulverized coal and a binder are formed into pellets. Second, the pellets, two to three layers deep, are heated in a gas-fired rotary hearth furnace for 15-20 minutes to produce sponge iron. Subsequently, the iron must be de-sulphurized. The coal in the pellets provides much of the energy required in the second phase.

Integrated Mills
These facilities make steel by processing iron ore and other raw materials in blast furnaces. Technically, only the hot end differentiates integrated mills from mini-mills. However, the differing technological approaches to molten steel imply different scale efficiencies and, therefore, separate management styles, labor relations and product markets. Nearly all domestic integrated mills specialize in flat-rolled steel or plate.

Integrated Producer
A producer who also owns the smelting and semi-fabricating facilities.

The placing of a sheet of paper between two adjacent layers of metal to facilitate handling and shearing of rectangular sheets, or to prevent sticking or scratching.

Intermediate Annealing
An annealing treatment given to wrought metals following cold work hardening for the purpose of softness prior to further cold working. (See Process Annealing)

Interrupted Aging
The aging of an alloy at two or more temperatures by steps, and cooling to room temperatures after each step. Compare with Progressive Aging.

Interstitial Free Steel
A recently developed sheet steel product with very low carbon levels that is used primarily in automotive deep-drawing applications. Interstitial Free Steel's improved ductility (drawing ability) is made possible by vacuum degassing.

Investment Casting
(1) Casting metal into a mold produced by surrounding (investing) an expendable pattern with a refractory slurry that sets at room temperature after which the wax, plastic, or frozen mercury pattern is removed through the use of heat. Also called precision casting, or lost-wax process.
(2) A casting made by the process.

(Chemical symbol Fe.) Element No. 26 of the periodic system; Atomic weight 55.85. A magnetic silver white metal of high tensile strength, ductile and malleable. Melting point of pure iron about 2795 (degrees) F. Chemically iron is chiefly base forming. The principal forms of commercial iron are steel, cast iron and wrought iron.

Iron Carbide
One of several substitutes for high-quality, low-residual scrap for use in electric furnace steelmaking. Iron carbide producers use natural gas to reduce iron ore to iron carbide.

Iron Ore
Mineral containing enough iron to be a commercially viable source of the element for use in steelmaking. Except for fragments of meteorites found on Earth, iron is not a free element; instead, it is trapped in the earth's crust in its oxidized form. 

Thinning the walls of deep drawn articles by reducing the clearance between punch and die.

Isothermal Annealing
A process on which a ferrous alloy is heated to produce a structure partly or wholly austenitic, and is then cooled to and held at a temperature that causes transformation of the austenite to a relatively soft ferrite-carbide aggregate

Isothermal Transformation
A change in phase at any constant temperature.

Isothermal Transformation (IT) Diagram
A diagram that shows the isothermal time required for transformation of austenite to commence and to finish as a function of temperature. Same as time-temperature-transformation (TTT) diagram or S-curve.

Izod Test
A pendulum type of single-blow impact test in which the specimen, usually notched, is fixed at one end and broken by a falling pendulum. The energy absorbed, as measured by the subsequent rise of the pendulum, is a measure of impact strength or notch toughness.