ABRASION RESISTANCE: Resistance to frictional rubbing, as distinct from resistant to knocks and impacts.
Annealing: A process involving heating and cooling, applied usually to induce softening. The term is also used to cover treatment to:-
- Remove stresses
- Alter mechanical or physical properties
- Produce a definite microstructure
- Remove dissolved glass
AUSTENITIC: The largest category of stainless steel, accounting for about 70 per cent of all production. The
austenitic class offers the most resistance to corrosion in the stainless group, owing to its substantial nickel
content and higher levels of chromium. Austenitic stainless steels are hardened and strengthened through
cold working instead of heat treatment.
Bend test: A test of ductility where a test piece must withstand, without fracture, bending through a
specific angle around a specified diameter.
Camber: The deviation of a side edge of metal sheet of strip from a straight line.
Chalking: A chalk-line formation on the surface of an organic coating caused by the breakdown of the
surface layer of resin, releasing pigment particles and fillers normally bound by the resin. This normally
occurs after long-term exposure to sunlight.
Cold Rolling: Is the reduction of hot-rolled pickled steel strip to a specified thickness, using a series of
stands of rolls. This distorts the grain structure of the steel and also a loss of ductility.
COLD WORKING: Changing the structure and shape of steel by applying stress at low temperature.
Ductility: The ability of a metal to deform form a flat condition into a complex shape without fracture.
Elasticity: That property of a material which causes it to resume its original form after removal of a load.
ELECTRIC RESISTANCE WELDED (ERW) PIPE: Pipe made from strips of hot-rolled steel which are passed
through forming rolls and welded.
Finish: Finish refers to the degree of smoothness of lustre of the sheet.
Flatness: The flatness so sheet metal may be defined as the absence of any waviness or buckle.
Galvanising: The process of applying a coating of zinc to a surface of iron on steel to provide a corrosion
resistant surface. Zinc coating may be applied by hot-dipping or electroplating.
Gloss: The degree to which a painted surface possesses the property of reflecting light in a mirror like
manner. COLORBOND® steel surfaces are produced in 10 per cent, 25 per cent and 80 per cent gloss.
Heat Treatment: An operation or combination of operations involving the heating or cooling of a metal
or alloy in a solid state for the purpose of obtaining desired conditions or properties.
Killed steel: A steel with de-oxidants such as aluminium or silicon added before casting molten steel to
remove oxygen and so prevent evolution of carbon monoxide and chemical segregation during cooling.
Lock seaming: The closing of a tight seam of lock-formed edges of sheet metal. Snap lock-seam.
Lustre: Lustre finish is a smooth finish for electroplating achieved by using special prepared rolls. Some
surface preparation by the plater may be necessary.
Matt: Cold-rolled products are available with either a matt or lustre finish. The matt finish is produced by
rolling with mechanically roughened rolls.
Mechanical properties: Properties relating to the behaviour of materials under load in conventional
mechanical tests. Such as elastic moduli, tensile strength, elongation, hardness.
Normalising: Heated steel to, and if necessary holding at, a suitable temperature above the
transformation range, followed by cooling in a still atmosphere to ambient temperature in order to produce
a medium-to fine pearlite microstructure.
Pickling: Removal of oxide films from metal by immersion in an acid. The process is applied to scale
removal from metal prior to operations such as cold rolling, wire drawing and electroplating. Absorption
of hydrogen may occur in pickling causing embrittlement of hard steels and necessitating low temperature
annealing for its removal.
Pressing: Is a metal working process in which a flat blank, constrained between two surfaces, is forced by
a punch to take a required shape.
Primer: The first coat of a painting system applied to an unpainted surface. It normally has very good
adhesion and corrosion inhibitive properties.
Rolling direction: The direction in which strip has been rolled. Longitudinal or Transverse.
Scale: Layers of iron oxide formed on the surface of hot steel when oxygen in the air combines with iron
from the steel.
Skin-Passing: A light cold rolling operation (about 1-2 per cent of cold works) which removes the yield
point in steel which otherwise causes coil break, fluting or stretcher strain in subsequent operations.
Spangle: Grain or crystal of zinc, or zinc/aluminium as appearing on hot-dipped metallic coated steel.
Stress Relieving: Heating a metal to, and holding it at, some temperature generally bellow
recrystallisation range, followed by uniform cooling, for the purpose of removing internal stresses.
Stretcher Levelled: As applied to sheets, indicates a standard of flatness. Originating from an early
method of gripping the ends of sheet and stretching it to remove buckles.
Strip: A continuously rolled flat product of any width and thickness, supplied rolled up into a coil form.
Temper: To modify hardness of metals. Adjustment of hardness of heat treated article by controlled
heating after quenching. Increase of hardness by cold rolling. The degree of cold rolling is variable
depending on the required hardness and is more than that of skin-passing.
Tensile test: A standard sample of material is placed between two jars and drawn apart in a tensile
testing machine until fracture. The ultimate tensile strength is the load divided by the cross section area of
the sample.
Wash coat: The coating applied to the back or exposed side of the painted strip.
Yield Point / Yield strength: Defined in engineering and materials science as the stress at which a
material begins to deform plastically. Prior to yield point, the material will deform elastically and will return
to its original shape when the applied stress is removed. Once the yield point is passed some fraction of the
deformation will be permanent and non-reversible.