|
Ragged Edges |
Edges of Sheet or Strip which are
torn, split, cracked, ragged or burred or otherwise disfigured. |
|
Recovery |
- Reduction or removal of
work-hardening effects, without motion of large-angle grain
boundaries.
- The removal of residual stresses
by localized plastic flow as the result of low-temperature
annealing operations; performed on cold worked metals without
altering the grain structure or strength properties
substantially.
|
|
Recrystallization |
- A process whereby a distorted
grain structure of cold worked metals is replaced by a new,
stress-free grain structure as a result of annealing above a
specific minimum temperature for a specific time.
- The change from one crystal
structure to another, as occurs on heating or cooling through a
critical temperature.
- The formation of a new,
strain-free grain structure from that existing in cold worked
metal, usually accomplished by heating.
|
|
Recrystallization Temperature |
The approximate minimum temperature
at which complete recrystallization of a cold worked metal occurs
within a specified time. |
|
Recystallization Annealing |
Annealing cold worked metal to
produce a new grain structure without a phase change. |
|
RCS |
Abbreviation for Rigid Container
Sheet. |
|
Reduction of Area |
- Commonly, the difference,
expressed as a percentage of original area, between the original
cross-sectional area of a tensile test specimen and the minimum
cross-sectional area measured after complete separation.
- The difference, expressed as a
percentage of original area, between original cross-sectional
area and that after straining the specimen.
|
|
Refined Aluminum |
Aluminum of very high purity (99.950
percent or higher) obtained by special metallurgical treatments. |
|
Reflector Sheet |
An alclad product containing on one
side a surface layer of high-purity aluminum superimposed on a core
or base alloy of commercial-purity aluminum or an aluminum-manganese
alloy. The high-purity coating imparts good polishing
characteristics and the core gives adequate strength and
formability. |
|
Reheating |
Heating metal to hot-working
temperature. In general no structural changes are intended. |
|
Remelt Ingot |
A cast form suitable for remelting. |
|
Reoil |
Oil put on the sheet after cleaning
and before coiling for shipment to prevent water stain. |
|
Reroll Stock |
(Foil Stock, Sheet Stock) A
semifinished rolled product of rectangular cross-section in coiled
form suitable for further rolling. |
|
Residual Elements |
Small quantities of elements
unintentionally present in an alloy. |
|
Residual Stress |
- Stress present in a body that is
free of external forces or thermal gradients.
- Macroscopic stresses that are set
up within a metal as the result of non-uniform plastic
deformation. This deformation may be caused by cold working or
by drastic gradients of temperature from quenching or welding.
|
|
Residuals |
'Incidental' or 'tramp' elements not
named in a specification. These inclusions are usually due to
contaminated scrap. |
|
Resilience |
The tendency of a material to return
to its original shape after the removal of a stress that has
produced elastic strain. |
|
Rockwell Hardness (Test) |
A standard method for measuring the
hardness of metals. The hardness is expressed as a number related to
the depth of residual penetration of a steel ball or diamond cone
(brale) after a minor load of 10 kilograms has been applied to hold
the penetrator in position. This residual penetration is
automatically registered on a dial when the major load is removed
from the penetrator. Various dial readings combined with different
major loads, five scales designated by letters varying from A to H;
the B and C scales are most commonly in use. |
|
Roll Forming |
An operation used in forming sheet.
Strips of sheet are passed between rolls of definite settings that
bend the sheet progressively into structural members of various
contours, sometimes called molded sections. |
|
Roll Chatter |
(Mark, Chatter) Numerous intermittent
lines or grooves that are usually full width and perpendicular to
the rolling or extrusion direction. |
|
Roll Coating |
(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." |
|
Roll Grind |
The uniform ground finish on the work
rolls which is imparted to the sheet or plate during rolling. |
|
Roll Mark |
A raised area formed during rolling
by the imprint of a depression in a roll. |
|
Roll Pickup |
Small particles of aluminum and
aluminum oxide generated in the roll bite which subsequently
transfer to the rolled product. It may be distributed uniformly
and/or in streaks. See also "Streak, Coating". |
|
Rolled-In Metal |
An extraneous chip or sliver of metal
rolled into the surface. |
|
Rolled-In Scratch |
A scratch that occurs during the
fabricating process and is subsequently rolled over. |
|
Roller Leveling |
- Passing sheet or strip metal
through a series of staggered small rolls so as to flatten the
metal. This method is relatively ineffective in removing defects
such as buckles, wavy edges, corrugations, twists, etc., or from
steel in the higher hardness ranges.
- Leveling by passing flat stock
through a machine having a series of small-diameter staggered
rolls.
|
|
Rolling |
- Reducing the cross-sectional area
of metal stock, or otherwise shaping metal products, through the
use of rotating rolls.
- A term applied to the operation of
shaping and reducing metal in thickness by passing it between
rolls which compress, shape and lengthen it following the roll
pattern.
|
|
Rolling Direction (in rolled metal) |
The direction, in the plane of the
sheet, perpendicular to the axes of the rolls during rolling. |
|
Rolling Ingot |
A cast form suitable for rolling. |
|
Rolling Mills |
Equipment used for rolling down metal
to a smaller size or to a given shape employing sets of rolls the
contours of which determine or fashion the product into numerous
intermediate and final shapes, e.g., blooms, slabs, rails, bars,
rods, sections, plates, sheets and strip. |
|
Rotary Shear (Slitting Machine) |
A cutting machine with sharpened
circular blades or disc-like cutters used for trimming edges and
slitting sheet and foil. NOTE: cutter discs are also employed in
producing circles from flat sheets but with differently designed
machines. |
|
Rolling Slab |
A rectangular semifinished product,
produced by hot rolling fabricating ingot and suitable for further
rolling. |
|
Rough Machining |
Machining without regard to finish,
usually to be followed by a subsequent operation. |
|
Rub Mark |
A minor form of scratching consisting
of a large number of very fine scratches or abrasions. |
