I – L

Idiomorph
A particle of a phase the has a regular external shape.

Immersed Scanning
In ultrasonics, 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 ffracture a material, usually measured by means of an Izod or Charpy test. The type of speciment and testing conditions affect the values and therfore should be specified.

Impact Strength

This is the ability of a metal to withstand high-energy impact without fracturing. The most common tests to determine impact strength are Charpy and Izod, and the results are noted in foot pounds of energy.

Impact Test
A test to determine the behavior of materials when subjected to high rates of loading,usually in bending, tension, or torsion. The quantity measured is the energy absorbed in breaking the specimen by a single blow, as in the Charpy or Izod.

Impurities
Elements or compounds whose presence in a material is undesired.

Inclusion
A nonmetallic material in a solid metallic matrix.

Inclusions
Particles of impurities (usually oxides, sulfides, silicates, etc.) that are held mechanically or are formed during the solidification or by subsequent reaction within the solid metal.

Indentation Hardness
The resistance of a meterial to indentation. This is the usual type osf hardness test, in which a pointed or rounded indenter is pressed into a surface under a substantially static load.

Indirect Extruding

In indirect extrusion (backward extrusion), the die is at the ram end of the stock and the product travels in the opposite direction as the ram, either around the ram or up through the center of a hollow ram.

Induction Hardening
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.

Ingot
A casting for subsequent rolling or forging.

Ingot Iron
Commercially pure iron.

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

Inside Diameter (I.D.)

This refers to the opening in the center of the coil. When you take up or wind up a coil in any operation, it is wrapped around a mandrel. After you have finished the operation, the mandrel is contracted so that the coil can be removed from it. The diameter of the mandrel defines the inside diameter of the coil.

Intercrystalline
Between crystals, or between grains. Same as intergranular.

Inter-Granular Corrosion

This occurs when the metal has been sensitized by passing through the temperature range of 800 to 1650oF causing chromium carbides to form in the grain boundaries and thereby pulling corrosion resistant chromium out of the areas adjacent to the grain boundaries and making these areas susceptible to corrosive attack.

Interleaving
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 softening prior to further cold working.

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 termperature after each step. Compare with progressuve aging.

Interrupted Quenching
Quenching in which the metal object being quenched is removed from the quenching medium while the object is at a temperature substantially higher than that of the quenching medium.

Interstitial Solid Solution
A solid solution in which the solute atoms occupy (interstitial) positions between the atoms in the structure of the solvent.

Intracrystalline
Within or across crystals or grains. Same as transcrystalline and transgranular.

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 frozed mercury pattern is removed through the use of heat. Also called precision casting, or lost-wax process. (2) A casting made by the process.

Iron
An element that has an average atomic number of 55.85 and that always, in engineering practice, contains small but significant amounts of carbon. Thus iron-carbon alloys containing less than about 0.1% C may be referred to as irons. Alloys with higher carbon contents are always termed steels.

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

Iron Pipe Size (I.P.S.)

Same as nominal size from 1/8 inch to 12 inch.

 

ISO

International Organization for Standardization – Prepares specifications. Both Canada and the United States are ISO members and participate in the ISO specification development.

Isothermal Annealing
A process in which a ferrous alloy is heated to produce a structure partly or wholly austenitic, and is then cooled to and held at a temperaure 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.

Jig Saw Steel
Hardened, tempered and bright polished with round edges. Carbon content .85. Ranges of sizes .039 to 393 in width and .016 to .039 in thickness.

Kerf

The amount of metal lost in a cutting process generally equal to the width of the flame or the width of the blade.

Killed Steel
The term killed indicates that the steel has been sufficiently deoxidized to quiet the molten metal when poured into the ingot mold. The general practice is to use aluminum ferrosilicon or manganese as deoxidizing agents. A properly killed steel is more uniform as to analysis and is comparatively free from aging. However, for the same carbon and manganese content Killed Steel is harder than Rimmed Steel. In general all steels above 0.25% carbon are killed, also all forging grades, structural steels from 0.15% to 0.25% carbon and some special steels in the low carbon range. Most steels below 0.15% carbon are rimmed steel.

Kind Band (deformation)
In polycrystalline materials, a volume of crystal that has rotated physically to accommodate differential deformation between adjoining parts of a grain while the band itself has deformed homogeneously. This occurs by regular bending of the slip lamellae along the boundaries of the band.

Kip
A load of 1000 lbs.

KSI

K equals 1000 PSI. . . thus the term is actually K (1000) PSI. The P has been dropped and KSI is the new term. (i.e. 50 KSI = 50,000 PSI)

Ladle Analysis
A term applied to the chemical analysis representative of a heat of steel as reported by the producer. It is determined by analyzing a test ingot sample obtained during the pouring of the steel from a ladle.

Lamellar Tear
A system of cracks or discontinuities aligned generally parallel to the worked surface of a plate. Usually associated with a fusion weld in thick plate.

Laminations
A defect appearing in sheets or strips as a segregation or in layers. To become divided, caused by gas pockets in the ingot.

Lap
A surface defect, appearing as a seam, caused by fording over hot metal, fins, or sharp corners and then rolling or forging them into the surface, but not welding them.

Lap-Weld
A term applied to a weld formed by lapping two pieces of metal and then pressing or hammering, and applied particularly to the longitudinal joint produced by a welding process for tubes or pipe, in which the edges of the skelp are beveled or scarfed so that when they are overlapped they can be welded together.

Lath Martensite
Martensite formed, partly in steel containing less than about 1.0% C and solely in steels containing less than about 0.5% C, as parallel arrays or packets of lath-shape units about 0.1 to 0.3 m thick, and having a habit plane that is close to {111}.

Lattice
Space lattice. Lattice lines and lattice planes are lines and planes chosen so as to pass through collinear lattice points, and non-collinear lattice points, respectively.

Leveling
Flattening rolled metal sheet or strip.

Light Metal
One of the low-density metals such as aluminum, magnesium, titanium, beryllium, or their alloys.

Liquation
Partial melting of an alloy.

Liquidus
In a constitutional diagram, the locus of points representing the temperatures at which various components commence freezing on cooling or finish melting on heating.

Lithographic Sheet Aluminum
Sheet having a superior surface on one side with respect to freedom from surface imperfections and supplied with a maximum degree of flatness, for use as a plate in offset printing.

Logs

(See Ingot) Another name for extrusion ingots. An extrusion plant without its own casting facilities may purchase logs and saw them to billet lengths to minimize inventory.

Long Terne
A term applying to steel sheets that have been terne coated (Lead and Tin) by immersion in a bath of Terne Metal.

Longitudinal Direction
The principal direction of flow in a worked metal.

Low Brass
80% cu. A copper-Zinc alloy containing 20% zinc. Is a light golden color, very ductile, suitable for cupping, drawing, forming, etc. Because of its good strength and corrosion resistance it is used for flexible metal gose, metal bellows, etc.

Low Carbon Steels
Contain from 0.10 to 0.30% carbon and less than 0.60% manganese. (The product of Basic Oxygen, Bessemer, Open Hearth or Electric Processes.)

Low-Hydrogen Electrode
A covered arc-welding electrode that provides an atmosphere around the arc and molten weld metal which is low in hydrogen.

Luders Lines or Bands
Elongated surface markings or depressions caused by localized plastic deformation that results form discontinuous (inhomogeneous) yielding.