GLOSSARY

Acid Brittleness/Hydrogen Embitterment

Brittleness resulting from pickling steel in acid, hydrogen formed by interaction of iron and acid is absorbed and causes brittleness.

Aluminum Killed Steel

A steel where aluminum is used as a deoxidizing agent

Annealing

A slow heating and cooling process. Heating to and holding at a suitable temperature and then cooling at a suitable slow rate.

Austempering

Carbon steel is quenched above transformation ranges, in a medium having rate of high abstraction sufficiently high to prevent the transformation of high temperature formation products and then holding the alloy, until transformation is complete, at a temperature below that of pearlite formations and above that of martensite formation.

Bainite

A slender needle like acicular structure appearing in Spring Steel Strips characterized by toughness and greater ductility then tempered martensite.

Bend test

A test to determine ductility of flat rolled steel strip in which the strip is bent around its axis.

Bonderizing

A coating with a film composed of zinco phosphate in order to develop better surface for coating.

Camber

Edgewise curvature, a lateral deviation of an edge from a straight line. Lateral departure of the edge of the material from straight line forming a chord.

Carbide

A compound of carbon with one or more metallic elements.

Cold rolling

Rolling metal at a temperature below the softening point of metal to create strain hardening. Cold rolling changes the mechanical properties of strip and produces combination of hardness ductility stiffness etc. known as temper.

Decarburisation

Removal of carbon from outer surface of steel.

Dish

A concave shape of strip, across the width.

Elongation

Increase in length which occurs before fracture of Steel.

Endurance limit

Maximum alternating stress, which a given components/steel causing will withstand for indefinite number of times without fatigue failure.

Grain

An individual crystal in a polycrystalline metal or alloy.

Grain size

A measure of the areas or volumes of grains in a poly crystalline material, usually expressed as an average when the individual sizes are fairly uniform. Grain sizes are reported in terms of number of grains per unit area or volume, in terms of average diameter or as a grain size number derived from area measurement.

Grain boundary

The regions of a metal between individual grains. Atoms in these boundaries adopt positions of equilibrium between the lattices on either side, and are therefore in a state of local desender, depending upon the angle between the lattice axis on either side.

Hardenability

The ability of steel to harden in depth. It is the property that determines the depth and distribution of hardness induced by quenching.

Grain growth

An increase in metals crystal size as annealing temperature is raised. Growth occurs by invasion of crystal arears by other crystals.

Hardness

Degree to which a metal will resist cutting, abrasion, penetration, bending & stretching.

Inclusion

Particulars of impurities such as oxides, sulphites, silicates, etc

Laminations

A defect appearing in steel strip segregation or layer caused by packets of gas in ingots.

Martensite

A distinctive needle like structure existing in steel as on transition range in transformation of austenite. It is the hardest constituent of steel. A meta stable phase of steel formed by a transformation of austenite below Ms temperature. It is an interstitial super saturated of carbon in iron having body center tetragonal lattice. Its structure is characterized by a acicular ar needle like distinct pattern.

Mechanical spring

Spring produced by cold forming with or without subsequent heat treatment.

Microstructure

The structure of strip specimen as revealed in microscope.

Oil hardening

A process of hardening by heating within or above the transformation range and quenching in oil.

Quenching

In the heat treatment of steel, the step of cooling metals rapidly in order to obtain desired properties’

Pearlite

Lamellar structure resembling mother of pearl. A compound of iron and carbon occurring in steel as a result of transformation of austenite into aggregations of ferrite and iron carbide.

Permanent set

Deformation of strip under stress after passing the elastic limits.

Scleroscope hardness text

A method of measuring hardness in which a diamond pointed hammer drops from a smooth tube and the rebound distance is measured.

Rockwell hardness text

A method of measuring hardness. The hardness is expressed as a number related to the depth of the residual penetration. A test for determining the hardness of a material based on the depth of penetration of a specified penetrator in to the specimen under certain arbitrarily fixed condition of test. A hardness test where the loss in kinetic energy of a falling diamond tipped metal ‘tup’, absorbed by indentation upon impact of the tup on the metal being tested is indicated by the height of rebo.

Self hardening steel

A steel with sufficient carbon or alloying element to form martensite through air hardening.

Shims

A shiny thin hardened & tempered steel strip for tool, die & machines alignment.

Spherodizing

Process of prolonged heating and slow cooling which will convert carbides in spheroidal or globular shape in steel.

Spring back

An indicator of elastic stress. Measured as increase in diameter of a curved strip after removing it from mandrel where it was held.

Stress relieving

Reducing stresses by heating to a suitable temperature, holding long enough to reduce residual stresses and then cooling slowly enough to minimize the development of new residual stresses.

Tempering

A process of reheating quench hardened or normalized material to a temperature below transformation range and then cooling at any rate desired.

Temper brittleness

Brittleness that results when certain steels are held within or are cooled slowly through a certain range of temperature below the transformation range. The brittleness is revealed by notched bar impact tests at or below room temperature.

Yield Point

The load per unit of original cross section which, in soft steel a marked increase in deformation occurs without increase in load.

Yield strength

The stress load at which steel takes permanent set. The stress at which a material exhibits a specified deviation from proportionality of stress and strain. An offset of 0.2% is used for many steels.