|
SAE |
Abbreviation for Society of
Automotive Engineers. This organization has specified common and
alloy steels and copper base alloys in accordance with a numerical
index system allowing approximation of the composition of the metal.
The last two digits always indicate the carbon content, usually
within 0.05%. |
|
Salt Spray Test |
An accelerated corrosion test in
which the metal specimens are exposed to a fine mist of salt water
solution either continuously or intermittently. |
|
Sample |
A part, portion, or piece taken for
purposes of inspection or test as representative of the whole. |
|
Scrap |
Material unsuitable for direct use
but usable for reprocessing by re-melting. |
|
Scratch |
A sharp linear indentation in the
surface of the metal. |
|
Scratch Brushed Finish |
Finish obtained by mechanically
brushing the surface with wire bristle brushes, by buffing with
greaseless compound or by cold rolling with wire bristled rolls on
scratch etched finish. |
|
Scratch, Friction |
A scratch caused by relative motion
between two contacting surfaces. |
|
Scratch, Handling |
A more severe form of rub mark. |
|
Scratch, Machine |
An indentation which is straight, is
in the rolling direction and is caused by contact with a sharp
projection on equipment. |
|
Scratch, Oscillation |
Minor indentations at an angle to the
rolling direction that result from coil oscillation during unwinding
or rewinding. |
|
Scratch, Rolled-In |
A scratch which is subsequently
rolled. It will then appear as a grayish white ladder (distinct
transverse lines within the longitudinal indentation). |
|
Scratch, Tension |
A short longitudinal indentation
parallel to the rolling direction. Also referred to as
"Scratch, Slippage". |
|
Segregation |
- Nonuniform distribution of
alloying elements, impurities or phases.
- In an alloy, concentration of
alloying elements at specific regions, usually as a result of
the primary crystallization of one phase with the subsequent
concentration of other elements in the remaining liquid.
|
|
Segregation Banding |
In homogeneous distribution of
alloying elements aligned on filaments or plates parallel to the
direction of working. |
|
Self Diffusion |
The spontaneous movement of an atom
to a new site in a crystal of its own species. |
|
Semi-Permanent Mold Casting |
A permanent mold casting which is
made using an expendable core such as sand. |
|
Sendzimir Mill |
A mill having two work rolls of 1 to
2 1/2-in diam. each, backed up by two rolls twice that diameter and
each of these backed up by bearings on a shaft mounted eccentrically
so that rotating it increases the pressure between bearings and
backup rolls. |
|
Shear |
- A type of cutting operation in
which the metal object is cut by means of a moving blade and
fixed edge or by a pair of moving blades that may be either flat
or curved.
- That type of force that causes or
tends to cause two contiguous parts of the same body to slide
relative to each other in a direction parallel to their plane of
contact.
|
|
Shear Bands (deformation) |
Bands in which deformation has been
concentrated inhomogeneously in sheets that extend across regional
groups of grains. Usually only one system is present in each
regional group of grains, different systems being present in
adjoining groups. The bands are noncrystallographic and form on
planes of maximum shear stress (55(degrees) to the compression
direction). They carry most of the deformation at large strains.
Compare microbands. |
|
Shear Crack |
A diagonal, transgranular crack
caused by shear stresses. |
|
Shear Strength |
The stress required to produce
fracture in the plane of cross section, the conditions of loading
being such that the directions of force and of resistance are
parallel and opposite although their paths are offset a specified
minimum amount. |
|
Shearing |
A machine action capable of reducing
the width and/or the length of flat rolled products. The movement is
similar to that of a paper cutter with a fixed bottom blade and a
movable top blade. Material to be sheared is placed between the two
blades against a fixed stop, the machine is activated, and the top
blade moves downward shearing the material in two. The top blade
then returns to its topmost position awaiting the next activation.
Material is repositioned and recut as often as necessary to achieve
the required dimensions. |
|
Sheet |
A flat-rolled metal product of some
maximum thickness and minimum width arbitrarily dependent on the
type of metal. Sheet is thinner than plate.
Alclad Sheet:
Composite sheet comprised of an aluminum alloy core having on both
surfaces (if one side only, Alclad One Side Sheet) a metallurgically
bonded aluminum or aluminum alloy coating that is anodic to the
core, thus electrolytically protecting the core against corrosion.
Annodizing:
Sheet with metallurgical characteristics and surface quality
suitable for the development of protective and decorative films by
anodic oxidation processes.
Clad Sheet:
Composite sheet having on both surfaces (if on one side only, Clad
One Side Sheet) a metallurgically bonded coating, the composition of
which may or may not be the same as that of the core.
Coiled Sheet:
Sheet in coils with slit edges.
Coiled Sheet Circles:
Circles cut from coiled sheet.
Coiled Sheet Cut-to-Length:
Sheet cut to specified length from coils and which has a lesser
degree of flatness than Flat Sheet.
Flat Sheet:
Sheet with sheared, slit or sawed edges, which has been flattened or
leveled.
Flat Circles:
Circles cut from flat sheet.
Mill Finish Sheet (MF):
Sheet having a nonuniform finish, which may vary from sheet to sheet
and within a sheet, and may not be entirely free from stains or oil.
Odd-Shaped Sheet Blanks:
Sheet cut into shapes other than circles or rectangles.
One Side Bright Mill Finish Sheet
(1SBMF): Sheet having a
moderate degree of brightness on one side and a mill finish on the
other.
Painted Sheet:
Sheet, one or both sides of which has a factory-applied paint
coating of controlled thickness.
Panel Flat Sheet:
Sheet, which has a higher degree of flatness than Flat Sheet.
Standard One Side Bright Finish Sheet
(S1SBF): Sheet having a
uniform bright finish on one side, and a mill finish on the other.
Standard Two Sides Bright Finish
Sheet (S2SBF): Sheet
having a uniform bright finish on both sides. |
|
Sheet Stock, Coiled |
(Reroll Stock) A semifinished rolled
product of rectangular cross-section in coiled form suitable for
further rolling. |
|
Short Transverse Direction |
For plate, sheet and forgings, the direction through
the thickness perpendicular to both longitudinal and long transverse directions.
|
|
Side Crack |
Edge(s) containing crack, split,
and/or tear which is caused by inability to deform without
fracturing. |
|
Side Set |
A difference in thickness between the
two edges of sheet or plate. |
|
Silicon |
Chemical symbol Si. Element No. 14 of
the periodic system; atomic weight 28.06. Extremely common element,
the major component of all rocks and sands; its chemical reactions,
however, are those of a metalloid. Used in metallurgy as a
deoxidizing scavenger. Silicon is present, to some extent, in all
steels, and is deliberately added to the extent of approximately 4%
for electric sheets, extensively used in alternating current
magnetic circuits. Silicon cannot be electrodeposited. |
|
Slip |
Plastic deformation by irreversible
shear displacement of one part of a crystal relative to another in a
definite crystallographic direction and on a definite
crystallographic plane. |
|
Slip Direction |
The crystallographic direction in
which translation of slip takes place. |
|
Slip Line |
Trace of a slip plane on a viewing
surface. |
|
Slip Plane |
The crystallographic plane on which
slip occurs in a crystal. |
|
Slippage Scratch |
(Scratch, Tension) A short
longitudinal indentation parallel to the rolling direction. |
|
Slit Edges |
The edges of sheet or strip metal
resulting from cutting to width by rotary slitters. |
|
Slitting |
- Cutting sheet or strip metal to
width by rotary slitters.
- A high-speed method of cutting
sheet in coiled form to narrower width coils. Although there are
flat sheet slitters in existence, most machines will only
accommodate coiled products. Two circular knives, one above the
other with clearance between their edges determined by alloy
strength and thickness, are required for each cut to be made.
The knives are located on parallel spindles, and, with the
proper clearance set, produce a clean accurate cut as the sheet
passes through them. Material is payed off a coil at the head of
the line, travels through the slitter knives, and is rewound
into new coils at the end of the line. Normally, slitting is the
last mechanical operation performed on the metal before it
leaves the mill.
|
|
Slitter Hair |
Minute hair-like silver along edge(s)
due to shearing or slitting operation. |
|
Sliver |
Slender fragment or splinter which is
a part of the material but not completely attached thereto. |
|
Sliver (defect) |
Loose metal piece rolled down onto
the surface of the metal during the rolling operations. |
|
Smudge |
A dark film of debris, sometimes
covering large areas, deposited on the sheet during rolling. Also
referred to as "Smut". |
| Snaking |
A series of
reversing lateral bows in coil products. This condition is caused by
a weaving action during an unwinding or rewinding operation. |
|
Soaking |
Prolonged heating of a metal at selected temperature. |
|
Soft Alloys |
Another of the terms given to the
lower strength, common alloys. Soft is misleading
because the 5XXX series is in this group and some of these alloys
have fairly high mechanical properties. The 1XXX, 3XXX, 5XXX and
most of the 6XXX alloy classes are all called soft alloys. |
|
Solid Solution |
- A single solid homogeneous
crystalline phase containing two or more chemical species.
- A solid crystalline phase
containing two or more chemical species in concentrations that
may vary between limits imposed by phase equilibrium.
|
|
Solidus |
In a constitutional diagram, the
locus of points representing the temperatures at which various
components finish freezing on cooling or begin to melt on heating. |
|
Solute |
The component of either a liquid or
solid solution that is present to the lesser or minor extent; the
component that is dissolved in the solvent. |
|
Solution Heat Treatment |
- A heat treatment in which an alloy
is heated to a suitable temperature, held at that temperature
long enough to cause one or more constituents to enter into
solid solution, and then cooled rapidly enough to hold these
constituents in solution.
- Heating an alloy to a suitable
temperature, holding at that temperature long enough to allow
one or more constituents to enter into solid solution, and then
cooling rapidly enough to hold the constituents in solution. The
alloy is left in a supersaturated, unstable state, and may
subsequently exhibit quench aging.
- A process in which an alloy is
heated to a suitable temperature long enough to allow a certain
constituent to enter into solid solution and is then cooled
rapidly to hold the constituent in solution. The metal is left
in a supersaturated, unstable state and may subsequently exhibit
age hardening.
|
|
Solvent |
The component of either a liquid or
solid solution that is present to the greater or major extent; the
component that dissolves the solute. |
|
Solvus |
In a phase or equilibrium diagram,
the locus of points representing the temperature at which solid
phases with various compositions coexist with other solid phases;
that is, the limits of solid solubility. |
|
Space Lattice (crystal) |
A system of equivalent points formed
by the intersections of three sets of planes parallel to pairs of
principal axes; the space lattice may be thought of as formed by the
corners of the unit cells. |
|
Space-Centered (concerning space
lattices) |
Body-centered. |
|
Special Tolerance |
A tolerance other than
"Standard". |
|
Specialty Sheet |
Sheet product offered for specific
end uses and usually designated by a name, rather than by alloy and
temper. |
|
Specific Gravity |
A numerical value representing the
weight of a given substance as compared with the weight of an equal
volume of water, for which the specific gravity is taken as 1.0000. |
|
Specimen |
That portion of a sample taken for
evaluation of some specific characteristic or property. |
|
Spinning |
The procedure of making sheet metal
discs into hollow shapes by pressing the metal against a rotating
form (spinning chuck) by a tool. |
|
Splice |
The end joint uniting two webs. |
|
Spot, Lube |
A non-uniform extraneous deposit of
lube on the coated sheet. |
|
Springback |
An indicator of elastic stresses,
frequently measured as the increase in diameter of a curved strip
after removing it from the mandrel about which it was held. The
measurement is employed as an indicator of the extent of recovery or
relief of residual stresses that has been achieved by the
transformation of elastic strain to plastic strain during heating or
stress relieving. |
|
Squareness |
Characteristic of having adjacent
sides or planes meeting at 90 degrees. |
|
Stabilizing |
A phenomenon peculiar to the 5XXX
series, or magnesium-bearing alloys, which tend to age soften during
storage. The resultant lowering of mechanical properties may cause
the metal to be below spec when the customer uses it. To prevent
this, most of these products are subjected to low temperature
thermal treatment before they are shipped from the mill. The result
of this treatment is a slight drop in the metal’s yield tensile
strength to a stable level that is no longer subject to age
softening. |
|
Stabilizing Treatment |
- A thermal treatment designed to
precipitate material from solid solution, in order to improve
the workability, to decrease the tendency of certain alloys to
age harden at room temperature, or to obtain dimensional
stability under service at slightly elevated temperatures.
- Any treatment intended to
stabilize the structure of an alloy of the dimensions of a part.
- Heating austenitic stainless
steels that contain titanium, columbium, or tantalum to a
suitable temperature below that of a full anneal in order to
inactivate the maximum amount of carbon by precipitation as a
carbide of titanium, columbium, or tantalum.
- Transforming retained austenite in
parts made from tool steel.
- Precipitating a constituent from a
nonferrous solid solution to improve the workability, to
decrease the tendency of certain alloys to age harden at room
temperature, or to obtain dimensional stability.
|
|
Stain, Heat Treat |
A discoloration due to non-uniform
oxidation of the metal surface during heat treatment. |
|
Stain, Oil |
Surface discoloration which may vary
from dark to brown to white and is produced during thermal treatment
by incomplete evaporation and/or oxidation of lubricants on the
surface. |
|
Stain, Saw Lubricant |
A yellow to brown area of surface
discoloration at the ends of the extruded length. It is the residue
of certain types of saw lubricants if they are not removed from the
metal prior to the thermal treatment. |
|
Stain, Water |
(Corrosion, Water Stain) Superficial
oxidation of the surface with a water film, in the absence of
circulating air, held between closely adjacent metal surfaces. |
|
Stamping |
A term used to refer to various press
forming operations in coining, embossing, blanking, and pressing. |
|
Straightness |
The absence of divergence from a
right (straight) line in the direction of measurement. |
|
Strain |
- A measure of the relative change
in the size of a body. Linear strain is the change per unit
length of a linear dimension. True (or natural) strain is the
natural logarithm of the ratio of the length at the moment of
observation to the original gauge length. Shearing strain is the
change in angle (expressed in radians) between two reference
lines originally at right angles. When the term is used alone,
it usually refers to linear strain in the direction of the
applied stress.
- A measure of the change in the
size or shape of a body, referred to its original size or shape.
Linear strain is the change per unit length of a linear
dimension. True strain (or natural strain) is the natural
logarithm of the ratio of the length at the moment of
observation to the original gauge length. Conventional strain is
the linear strain referred to the original gauge length.
Shearing strain (or shear strain) is the change in angle
(expressed in radians) between two lines originally at right
angles. When the term strain is used alone it usually refers to
the linear strain in the direction of the applied stress.
- Deformation produced on a body by
an outside force.
|
|
Strain Aging |
Aging induced by cold work. |
|
Strain Hardening |
An increase in hardness and strength
caused by plastic deformation at temperatures lower than the
recrystallization range. |
|
Streak (Stripe) |
A line, elongated mark, or stripe
causing nonuniformity of surface appearance; in the case of painted
sheet it is visible as a variation in gloss or color. |
|
Streak, Bright |
A bright superficial band or
elongated mark which produces a non-uniform surface appearance. |
|
Streak, Buff |
A dull continuous streak caused by
smudge buildup on a buff used at shearing or other operations. |
|
Streak, Burnish |
A bright region on the sheet caused
by excessive roll surface wear. |
|
Streak, Coating |
A banded condition caused by
non-uniform adherence of roll coating to a work roll. It can be
created during hot and/or cold rolling. If generated in the hot
rolling process, it is also called "Hot Mill Pickup". |
|
Streak, Diffusion |
Surface discoloration which may vary
from gray to brown and found only on Alclad products. |
|
Streak, Dirt |
Surface discoloration which may vary
from gray to black, is parallel to the direction of rolling and
contains rolled in foreign debris. It is usually extraneous material
from an overhead location that drops onto the rolling surface and is
shallow enough to be removed by etching or buffing. |
|
Streak, Grease |
A narrow discontinuous streak caused
by rolling over an area containing grossly excessive lubricant
drippage. |
|
Streak, Grinding |
A streak with a helical pattern
appearance transferred to a rolled product from a work roll. |
|
Streak, Heat |
Milky colored band(s) parallel to the
rolling direction which vary in both width and exact location along
the length. |
|
Streak, Herringbone |
Elongated alternately bright and dull
chevron markings. |
|
Streak, Leveller |
A streak on the sheet surface in the
rolling direction caused by transfer from the leveler rolls. |
|
Streak, Mill Buff |
A non-uniform surface appearance
parallel to the rolling direction. Same as "Streak, Roll". |
|
Streak, Pickup |
A banded condition caused by
non-uniform adherence of roll coating to a work roll. It can be
created during hot and/or cold rolling. If generated in the hot
rolling process, it is also referred to as "Streak,
Coating". |
|
Streak, Roll |
A non-uniform surface appearance
parallel to the rolling direction. Also referred to as "Streak,
Mill Buff". |
|
Streak, Structural |
A non-uniform appearance on an etched
or anodized surface caused by heterogeneities (variabilities)
remaining in the metal from the casting, thermal processes or hot
working stages of fabrication. |
|
Stress |
- Force per unit area. True stress
denotes stress determined by measuring force and area at the
same time. Conventional stress, as applied to tension and
compression tests, is force divided by original area. Nominal
stress is stress computed by simple elasticity formula.
- Force per unit area, often thought
of as force acting through a small area within a plane. It can
be divided into components, normal and parallel to the plane,
called normal stress and shear stress, receptively. True stress
denotes the stress where force and area are measured at the same
time. Conventional stress, as applied to tension and compression
tests, is force decided by the original gauge length. Shearing
strain (or shear strain) is the change in angle (expressed in
radians) between two lines originally at right angles. When the
term strain is used alone it usually refers to the linear strain
in the direction of the applied stress.
- Deforming force to which a body is
subjected, or, the resistance which the body offers to
deformation by the force.
|
|
Stress Corrosion Cracking |
- Regardless of product form, mill
processing subjects aluminum to varying degrees of deformation
caused by hot and cold temperature exposures, inconsistent and
unbalanced stresses, etc. The result of all this is hidden
internal stresses within the products which can distort the
metal when a portion of the metal or its surface is removed.
Should the ultimate user plan to remove large amounts of metal,
do extensive machining or perform a myriad of other critical
processes, the metal might go completely beyond the acceptable
degree of flatness or shape. To circumvent this, the mills are
equipped to stress-relieve metal that is targeted for those
types of operations by stretching, compressing, or thermal
processes - depending on product form, alloy and temper.
- Failure by cracking resulting from
selective directional attack caused by the simultaneous
inter-action of sustained tensile stress at an exposed surface
with the chemical or electrochemical effects of the service
environment.
|
|
Stress Relief |
Low temperature annealing for
removing internal stresses, such as those resulting on a metal from
work hardening or quenching. |
|
Stress Relieving |
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. |
|
Stress-Rupture Test |
A tension test performed at constant
temperature, the load being held at such a level as to cause
rupture. Also known as creep-rupture test. |
|
Stretch Forming |
A process of forming panels and cowls
of large curvature by stretching sheet over a form of the desired
shape. This method is more rapid than hammering and beating. |
|
Stretcher Leveling |
- Leveling where a piece of metal is
gripped at each end and subjected to a stress higher than its
yield strength to remove warp and distortion. Sometimes called
patent leveling.
- A method of making metal sheet or
strip dead flat by stretching.
|
|
Stretcher Straightening |
A process for straightening rod,
tubing, and shapes by the application of tension at the ends of the
stock. The products are elongated a definite amount to remove
warpage. |
|
Stretcher Strains |
- Elongated markings that appear on
the surface of some materials when deformed just past the yield
point. These markings lie approximately parallel to the
direction of maximum shear stress and are the result of
localized yielding. Same as Luders lines.
- Long vein-like marks appearing on
the surface of certain metals, in the direction of the maximum
shear stress, when the metal is subjected to deformation beyond
the yield point. Also termed Luders Lines. (Not a defect in No.
5 dead soft temper.)
|
|
Striation |
Longitudinal non-uniform coating
thickness caused by uneven application of the liquid coating. |
|
Strip |
A sheet of metal whose length is many
times its width. |
|
Structure |
The arrangement of parts; in
crystals, especially, the shape and dimension of the until cell, and
the number, kinds and positions of the atoms within it. |
|
Structural Streaks |
Streaks on etched or anodized
surfaces resulting from heterogeneities in the metal structure. |
|
Sub-boundary Structure (subgrain
structure) |
A network of low-angle boundaries
(usually with misorientations or less than one degree) within the
main grains of a microstructure. |
|
Subgrain |
A portion of a crystal or grain
slightly different in orientation from neighboring portions of the
same crystal. Generally, neighboring subgrains are separated by
low-angle boundaries. |
|
Substitutional Solid Solution |
A solid solution in which the solvent
and solute atoms are located randomly at the atom sites in the
crystal structure of the solution. |
|
Substrate |
The layer of metal underlying a
coating, regardless of whether the layer is base metal. |
|
Superficial Rockwell Hardness Test |
Form of Rockwell hardness test using
relatively light loads which produce minimum penetration. Used for
determining surface hardness or hardness of thin sections or small
parts, or where large hardness impression might be harmful. |
|
Surface Tear |
Minute surface cracks on rolled
products which can be caused by insufficient ingot scalping. |
