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Please note that the definitions below are provided for reference purposes only.
- Annealing
- A general term referring to the thermal treatment process involving heating
and cooling, usually applied to change mechanical or physical properties,
produce a desired microstructure.
- Annealing (Bright Annealing) - An annealing
process usually carried out in a controlled atmosphere furnace using
a reducing atmosphere to achieve desired mechanical properties with
minimum surface oxidation. The tube surface is relatively bright.
- Annealing (Normalizing) - An annealing process in which
a steel is heated to a temperature that is above the upper transformation
range and then cooled in air. A slight surface oxidation occurs during
this process. The tube surface has a black or blue color.
- Annealing (Solution Annealing) - An annealing
process in which stainless steel is heated to a suitable temperature
to ensure the solution of constituents, such as chromium carbides,
and cooled rapidly to hold these constituents in solution.
- Carbon Steel Tube - Steel tube containing only residual quantities of elements other than
carbon and manganese. Typical industrial AISI designate grades include
1008, 1010, 1020, 1026, 1030, 1035 etc.
- Cold Drawing - The process of pulling a tube
through a die and over a mandrel to reduce its diameter and/or wall
thickness to a specific outside diameter, inside diameter or wall
thickness. Higher tensile properties, tighter dementional tolerances,
and improved surface finish are obtained due to the cold working at
room temperature.
- Decarburization - The loss of carbon from the surface
of ferrous alloy as a result of heating in a medium that reacts with
the carbon.
- Dimensions of
Tubing - A round tube section
has three dimensions, any two of which may be measured. The three
dimensions are outside diameter (OD), inside diameter (ID), and wall
thickness (t or W). Nominal as applied to any of these dimensions
refers to the theoretical or stated single value of that dimension.
The dimensions ordinarily specified by the customer are termed "nominal".
Maximum and Minimum referring to the greatest and least values
of any dimension. Average dimensions are those secured by averaging
a series of micrometer readings.
- Elongation - The amount of permanent extension in the vicinity
of the fracture in the tension test; usually expressed as a percentage
of the original gauge length.
- Fatigue - The tendency for a metal to break at a point that
is considerably below the ultimate tensile strength due to the conditions
of repeated cyclic stressing considerably below the ultimate tensile
strength.
- Formability - The ease with which a metal can be shaped through
plastic deformation. Evaluation of the formability of a metal involves
measurement of strength, ductility, and the amount of deformation
required to cause fracture.
- Hardenability - In a ferrous alloy, the property that determines
the depth and distribution of hardness induced by quenching.
- Hardness - Resistance of metal to plastic deformation. Various
hardness tests such as Rockwell, Brinell, Vickers and Knoop may be
used.
- Heat-Affected Zone (HAZ) - That portion of the base metal that was
not melted during welding, but whose microstructure and mechanical
properties were altered by the heat.
- High-Strength Low-Alloy (HSLA) Steels -
Steels designed to provide better mechanical properties and/or greater resistance
to atmospheric corrosion than conventional carbon steels. They are
not considered to be alloy steels in the normal sense because they
are designed to meet specific mechanical properties rather than a
chemical composition.
Typical HSLA steels have minimum yield
strengths 50 ksi, 60 ksi, 70 ksi or 80 ksi.
The chemical composition of the specific
HSLA steel may vary for different product thickness to meet mechanical
property requirements. The HSLA steels have low carbon contents
(0.05 to ~0.20% C) in order to produce adequate formability and
weldability. Small quantities of chromium, nickel, molybdenum, copper,
nitrogen, vanadium, niobium and titanium are used in various combinations.
- Impact Test - A test to determine the energy absorbed in fracturing a test
bar at high velocity. The typical test for tubing is a notch test
with an artificial notch present and tested at the various temperatures.
- Imperfection - When referring to the physical condition of a product,
any departure of a quality characteristic from its intended level
or state. When referring to the dimensional condition of a product,
any dimensional characteristic that is out of intended range. The
existence of an imperfection does not imply nonconformance,
nor does it have any implication as to the usability of a product
in service. An imperfection should be rated on a scale of severity,
in accordance with applicable specifications, to establish whether
or not the product is of acceptable quality.
- Inclusion - A physical and mechanical discontinuity occurring within a
metal product, usually consisting of nonmetallic foreign material.
Inclusions are often capable of transmitting some structural stresses
and energy fields, but to a noticeably different degree than from
the parent material. The foreign particles are usually compounds,
such as oxides, sulfides, silicates or combination of these.
- Killed Steel - During the steel making process, the molten metal
as it comes from the furnace contains more or less oxygen in the form
of dissolved oxides, the amount varying with the composition desired
and with certain conditions of steel making. If certain elements such
as manganese, silicon or aluminum are added in sufficient amounts
to molten steel in the ladle, the metal will solidify quietly without
evolution of gases. When processing rimmed steel and semi-killed steel,
killed steel is one of the methods of deoxidizing. Killed steel is
deoxidized with strong deoxidizing agent(s) to reduce the oxygen content
to a minimum so that no reaction occurs between carbon and oxygen
during solidification. Usually, killed steel has the best internal
cleanliness condition.
- Mechanical Properties - The properties of a material that reveal
its elastic and inelastic behavior when force is applied, thereby
indicating its suitability for mechanical applications; for example
tensile strength, yield strength, elongation, hardness, and fatigue
limit.
- Physical Properties - Properties of a material that are relatively
insensitive to structure and can be measured without the application
of force; for example, density, electrical conductivity, coefficient
of thermal expansion, magnetic permeability.
- Residual Stress - 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.
- Stainless - A trade name given to alloy steel that is corrosion
and heat resistant. The chief alloying elements are chromium, nickel,
molybdenum. By AISI definition, a steel is called "Stainless"
when it contains 10.5 % or more chromium.
- Stress Relieving - A process of reducing residual stresses in a metal
by heating the part to a suitable temperature and holding for a sufficient
time. This treatment may be applied to relieve stresses induced by
cold working or welding.
- Tensile Strength - The value obtained by dividing the maximum
load observed during tensile straining until breakage occurs by the
specimen cross-sectional area before straining. Also called "ultimate
strength".
- Tubing - A non-standardized hollow shaped product with a relatively
uniform wall thickness, generally round and manufactured to specified
requirements or dimensions. Chemical composition, mechanical properties
and other characteristics may be required for applications in automotive,
mechanical, pressure or structural uses. It is generally specified
to two dimensions, i.e., outside diameter (OD) and wall, inside diameter
(ID) and wall, or OD and ID.
- Welding, Electric Resistance - The method of joining metals
by passage of an electric current through the metal, whereby the resistance
of the metal results in a temperature increase at the joining surfaces
sufficient to weld. Upset pressure is also applied to insure sound
contact of the surfaces to be welded.
- Welding, Induction - A form of electric resistance welding wherein
the welding heat is generated within the metal by resistance to the
flow of an electric current induced in the metal by means of a circumferential
coil.
- Welding, Inert Arc - Arc welding in an atmosphere of an inert
gas which serves to protect the molten puddle from contamination and
oxidation by preventing air from coming in contact with the metal
while it is at elevated temperatures.
- Yield Strength - The stress at which a material exhibits a specified
limiting deviation from proportionality of stress to strain. An offset
of 0.2 %. is used for steel.
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