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backfill
Material placed in a drilled hole to fill space around
anodes, vent pipe, and buried components of a cathodic protection system.
bainite
A metastable aggregate of ferrite and cementite
resulting from the transformation of austenite at temperatures
below the pearlite range but above M the martensite start
temperature. Bainite formed in the upper part of the bainite transformation
range has a feathery appearance; bainite formed in the lower part of the
range has an acicular appearance resembling that of tempered martensite.
banded
structure
A segregated structure consisting of alternating
nearly parallel bands of different composition, typically aligned in the
direction of primary hot working.
base
A chemical substance that yields hydroxyl ions (OH ) when dissolved in water. Compare with acid.
base
metal
(1) The metal present in the largest proportion in an
alloy; brass, for example, is a copper-base alloy. (2) An active metal that
readily oxidizes, or that dissolves to form ions. (3) The metal to be brazed, cut, soldered, or welded. (4) After welding,
that part of the metal which was not melted.
beach
marks
Macroscopic progression marks on a fatigue fracture or
stress-corrosion cracking surface that indicate successive positions of the
advancing crack front. The classic appearance is of irregular elliptical or
semielliptical rings, radiating outward from one or more origins. Beach
marks (also known as clamshell marks or arrest marks) are typically found
on service fractures where the part is loaded randomly, intermittently, or
with periodic variations in mean stress or alternating stress. See also striation.
biaxial
stress
See principal stress (normal).
bimetallic
corrosion
(Galvanic Corrosion) Corrosion resulting from
dissimilar metal contact.
biological
corrosion
Deterioration of metals as a result of the metabolic
activity of microorganisms.
bipolar
electrode
An electrode in an electrolytic cell that
is not mechanically connected to the power supply, but is so placed in the
electrolyte, between the anode and cathode, that the part
nearer the anode becomes cathodic and the part nearer the cathode becomes
anodic. Also called intermediate electrode.
bituminous
coating
Coal tar or asphalt-based coating.
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black
liquor
The liquid material remaining from pulpwood cooking in
the soda or sulfate paper-making process.
black
oxide
A black finish on a metal produced by immersing it in
hot oxidizing salts or salt solutions.
blister
A raised area, often dome shaped, resulting from (1)
loss of adhesion between a coating or deposit and the base metal or (2)
delamination under the pressure of expanding gas trapped in a metal in a
near-subsurface zone. Very small blisters may be called pinhead blisters or
pepper blisters.
blow
down
(1) Injection of air or water under high pressure
through a tube to the anode area for the purpose of purging the annular
space and possibly correcting high resistance caused by gas blocking. (2) In
connection with boilers or cooling towers, the process of discharging a
significant portion of the aqueous solution in order to remove accumulated
salts, deposits, and other impurities.
blue
brittleness
Brittleness exhibited by some steels after being
heated to a temperature within the range of about 200 to 370 ºC (400
to 700 ºF), particularly if the steel is worked at the elevated
temperature.
blushing
Whitening and loss of gloss of a usually organic
coating caused by moisture. Also called blooming.
brackish
water
(1) Water having salinity values ranging from
approximately 0.5 to l7 parts per thousand. (2) Water having less salt than
seawater, but undrinkable.
breakdown
potential
The least noble potential where pitting or crevice
corrosion, or both, will initiate and propagate.
brightener
An agent or combination of agents added to an
electroplating bath to produce a smooth, lustrous deposit.
brine
Seawater containing a higher concentration of
dissolved salt than that of the ordinary ocean.
brittle
fracture
Separation of a solid accompanied by little or no
macroscopic plastic deformation. Typically, brittle fracture occurs by
rapid crack propagation with less expenditure of energy than for ductile
fracture.
burning
(1) Permanently damaging a metal or alloy by heating
to cause either incipient melting or intergranular oxidation. See also over-heating.
(2) In grinding, getting the work hot enough to cause discoloration or
to change the microstructure by tempering or hardening.
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