Radiograph
A photographic shadow image resulting from uneven absorption of penetrating radiation in a test object.
Radiography
A method of nondestructive inspection in which a test object is exposed to a beam of x-rays or gamma rays and the resulting shadow image of the object is recorded on photographic film placed behind the object. Internal discontinuities are detected by observing and interpreting variations in the image caused by differences in thickness, density, or absorption within the test object. Variations of radiography include electron radiography, fluoroscopy, and neutron radiography. Commonly referred to as RT.
Residual elements
Elements present in an Alloy in small quantities, but not added intentionally.
Rigging
The Engineering design, layout, and fabrication of pattern equipment for producing castings; including a study of the casting solidification program, feeding (risering) and gating, and fitting flasks.
Riser
Reservoir of molten metal from which casting feeds as it shrinks during solidification.
Riser, Blind
A riser that does not break through the top of the cope and is entirely surrounded by sand.
Riser, Open
A riser that breaks through the top of the cope; hot topping compound is applied to the exposed metal surface immediately after pouring.
Root of joint
The portion of a weld joint where the members are closest to each
other before welding. In cross section, this may be a point, a line or
an area.
Root pass
The first bead of a multiple-pass weld, laid in the root of joint.
SAE
Society of Automotive Engineers.
Salt fog test
An accelerated corrosion test in which specimens are exposed to a fine
mist of a solution usually containing sodium chloride but sometimes
modified with other chemicals; sometimes called a salt spray test.
Selenium
An element added to Stainless steel to improve machinability. Element 34; Symbol: Se.
Sensitization
In austenitic Stainless steels, the precipitation of chromium
carbides, usually at grain boundaries, on exposure to temperatures of
about 550 to 850 degrees C (about 1000 to 1550 degrees F), leaving the
grain boundaries depleted of chromium and therefore susceptible to
preferential attack by a corroding (oxidizing) medium.
SFSA
steel Founders’ Society of America.
Shear strength
Maximum shear stress a material is capable of withstanding without
failure.
Shielded metal arc welding
Arc welding in which the arc and the weld metal are protected by a gaseous atmosphere, the products of decomposition of the covering on a consumable metal electrode.
Shot blasting
Blasting with metal shot; usually used to remove deposits or scale more rapidly or more effectively than can be done by sand
blasting.
Shot peening
Cold working the surface of a metal by metal-shot impingement.
Shrinkage rule
A measuring ruler with graduations expanded to compensate for the
change in the dimensions of the solidified casting as it cools in the
mold.
Sigma phase
A hard, brittle, nonmagnetic intermetallic phase. Found in some Stainless steels after heating to temperatures between 1300 and 1800 F (700 and 1000 C).
Silicon
An important element, chemically classified as a nonmetal, metallurgically, as a metal. Added to steels as a deoxidizer, to Stainless steels to improve fluidity for casting and to control oxide film formation, to heat resisting Alloys for carburization resistance, and to some Ni-based Alloys for increased hardness. Element 14; Symbol: Si.
SMAW
Shielded Metal Arc Welding.
Soaking
Prolonged heating of a metal at a selected
temperature.
Solid
That material which has a tendency to resist any attempt to change its
size or shape.
Solidification
The change in state from liquid to solid on cooling through the
melting temperature or melting range.
Solidus
In a constitution or equilibrium diagram, the line representing the temperatures at which various compositions finish
freezing on cooling or begin to melt on heating.
Specific gravity
A numerical value representing the weight of a given substance as
compared with the weight of an equal volume of water at 39 degrees F
(3.9 degrees C), for which the specific gravity is taken as 1.000.
Specific heat
The ratio of the thermal capacity (the quantity of heat required to
produce a unit change in the temperature of a unit mass) of a substance to that of water at 15 C.
Specific volume
Volume of one gram of a substance at a specific temperature, usually
20 degrees C (68 degrees F).
Stainless steel
A wide range of steels containing chromium or chromium and other elements such as nickel, molybdenum, copper, manganese, and nitrogen,
exhibiting high resistance to corrosion.
steel
An iron-base Alloy containing carbon, usually manganese, and often other Alloying
elements.
Strain
A measure of the relative change in the size or shape of a body.
Strain rate
The time rate of straining for the usual tensile test.
Stress
Force per unit area, often thought of as force acting through a small
area within a plane.
Stress-corrosion cracking (SCC)
A cracking process that requires the simultaneous action of a
corrosive and sustained tensile stress. This excludes
corrosion-reduced sections that fail by fast fracture. It also
excludes intercrystalline or transcrystalline corrosion, which can
disintegrate an Alloy without applied or residual stress.
Stress-corrosive cracking may occur in combination with hydrogen
embrittlement.
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.
Stringer bead
A type of weld bead made without appreciable weaving motion.
Structure (Cast structure)
The size and disposition of the constituents of a metal as cast.
Sulfur
A nonmetallic element, occurring as an undesirable tramp (trace) element in most ferrous Alloys, but added to some grades to improve machinability. Element 16; Symbol: S.
SuperAlloy
An Alloy developed for very high temperature use where relatively high
stresses are encountered and where oxidation resistance is needed.
Temper
In heat treatment, to reheat hardened steel or hardened cast iron to
some temperature below the transformation temperature for the purpose of
decreasing hardness and increasing toughness. The process may also be applied to normalized steel.
Temperature
Degree of warmth or coldness in relation to an arbitrary zero measured
on one or more of accepted scales, as Centigrade, Fahrenheit, etc.
Tensile strength
The maximum stress in uniaxial tension testing which a material will
withstand prior to fracture. The ultimate tensile strength is
calculated from the maximum load applied during the test divided by
the original cross sectional area.
Thermocouple
A device for measuring temperatures, consisting of lengths of two
dissimilar metals or Alloys that are electrically joined at one end
and connected to a voltage-measuring instrument at the other end.
TIG Welding
Tungsten inert-gas welding.
Tool steel
Any of a class of carbon and Alloy steels commonly used to make tools.
Transformation ranges
Those ranges of temperature within which a phase (such as austenite) forms during heating and
transforms during cooling. The limiting temperatures of the
ranges depend on the composition of the Alloy and on the rate of
change of temperature, particularly during cooling.
Transformation temperature
The temperature at which a change in phase occurs. This term is
sometimes used to denote the limiting temperature of a transformation
range.
Transition temperature
An arbitrarily defined temperature that lies within the temperature
range in which metal fracture characteristics (as usually determined
by tests of notched specimens) change rapidly, such as from primarily
fibrous (shear) to primarily crystalline (cleavage) fracture.
Transverse
Literally, “across”, usually signifying a direction or plane
perpendicular to the direction of rolling.
TTT curve
Abbreviation for Time-Temperature-Transformation curve.
Tungsten
Tungsten is added to certain Stainless steels to improve resistance to pitting and crevice corrosion. It is a very pronounced carbide former and promotes ferrite. In steels, it improves toughness and prevents grain growth. Element 74; Symbol W.
Tungsten inert-gas welding
Inert-gas shielded welding using a tungsten electrode.
Ultimate tensile strength
The maximum tensile stress a metal can stand.
Ultrasonic testing
A nondestructive method of testing metal for flaws based on the fact
that ultrasonic waves are reflected and refracted at the boundaries of
a solid medium. Commonly referred to as UT.
Undercut
A groove melted into the base metal adjacent to the toe of a weld and left unfilled.
Vacuum induction melting
A process for remelting and refining metals in which the metal is
melted inside a vacuum chamber by induction heating. The metal may be
melted in a crucible, then poured into a mold.
Vanadium
In steels, refines the primary grain and thus the casting structure. Pronounced carbide former, thus providing increased wear resistance, edge holding quality, and high temperature strength. Element 23; Symbol: V.
Weave bead
A type of weld bead made with transverse oscillation.
Weldability
A specific or relative measure of the ability of a material to be
welded under a given set of conditions.
Welding
Joining two or more pieces of material by applying heat or pressure,
or both, with or without filler material, to produce a localized union
through fusion or recrystallization across the interface.
Welding procedure
The detailed materials, methods, and practices involved in the production of a weld.
Welding technique
The details of a welding operation that, within the limitations of a
welding procedure, are performed by the welder.
White cast iron
Cast iron that shows a white fracture because the carbon is in
combined form.
WPQR
Welding Procedure Qualification Record.
WPS
Welding Procedure Specification.
Yield ratio
The ratio of yield strength to ultimate tensile strength. Top