are normally quenched in cold water. The temperature
before quenching should be 85°F or less. Sufficient cold
water should be circulated within the quenching tanks
to keep the temperature rise under 20°F. This type of
quench will ensure good resistance to corrosion, and is
particular y important when heat-treating 2017 and
HOT WATER QUENCHING.Large forgings
and heavy sections can be quenched in hot or boiling
water. This type of quench is used to minimize distortion
and cracking, which are produced by the unequal
temperatures obtained during the quenching operation.
The hot water quench will also reduce residual stresses,
which improves resistance to stress corrosion cracking.
SPRAY QUENCHING.Water sprays are used to
quench parts formed from alclad sheets and large
sections of most alloys. Principal reasons for using this
method are to minimize distortion and to alleviate
quench cracking. This system is not usually used to
quench bare 2017 and 2024 due to the effect on their
Annealing serves to remove the strain hardening
that results from cold working and, in the case of the
heat-treated alloys, to remove the effect of the heat
treatment. Annealing is usually carried out in air
furnaces, but salt baths may be used if the melting point
of the bath is low enough. A bath made up of equal parts
by weight of sodium nitrate and potassium nitrate is
ANNEALING OF WORK HARDENED
MATERIAL.Annealing of material that was initially
in the soft or annealed condition but which has been
strain-hardened by cold working, such as 1100, 3003,
5052, etc., is accomplished by heating the metal to a
temperature of 349 ±5°C (660 ±10°F). It is only
necessary to hold the metal at this temperature for a
sufficient length of time to make certain that the
temperature in all parts of the load has been brought
within the specified range. If the metal is heated
appreciably above 354°C (670°F), there is a partial
solution of the hardening constituents, and the alloy will
age harden while standing at room temperature unless it
has been cooled very slowly. If the temperature is not
raised to 343°C (650°F), the softening may not be
complete. The rate of cooling from the annealing
temperature is not important. However, a slow cool is
desirable in case any part of the load may have been
heated above the recommended temperature range.
ANNEALING OF HEAT-TREATED ALLOYS.
The heat-treatable alloys are annealed to remove the
effects of strain hardening or to remove the effects of
solution heat treatment.
To remove strain hardening due to cold work, a
1-hour soak at 640° to 660°F, followed by air coding,
is generally satisfactory. This practice is also
satisfactory to remove the effects of heat treatment if the
maximum of softness is not required.
To remove the effects of partial or full heat
treatment, a 2-hour soak at 750° to 800°F, followed by
a maximum cooling rate of 50° per hour to 500°F, is
required to obtain maximum softness.
To remove the effects of solution heat treatment or
hardening due to cold work, the high zinc-bearing alloy
7075 should be soaked 2 hours at 775°F, air cooled to
450°, and soaked 6 hours at 450°. The stabilizing
temperature at 450° is necessary to precipitate the
soluble constituents from solid solution.
The annealing of solution heat-treated material
should be avoided whenever possible if subsequent
forming and drawing operations are to be formed. If
such operations are not severe, it is generally
advantageous to repeat the solution heat treatment and
form the material in the freshly quenched condition.
RECOMMENDED READING LIST
NOTE: Although the following references were
current when this TRAMAN was published, their
continued currency cannot be assured. Therefore, you
need to be sure that you arc studying the latest revision.
Nondestructive Inspection Methods, N A V A IR
01-1A-16, Naval Air Systems Command
Headquarters, Washington, D.C., 1 March 1990,
Change 1, 1 April 1991.
Aerospace MetalsGeneral Data and Usage Factors,
NAVAIR 01-1A-9, Naval Air Systems Command
Headquarters, Washington, D.C., 22 November
1967, Change 19, 1 September 1989.
Aeronautical and Support Equipment Welding,
NAVAIR 01-1A-34, Commander, Naval Air
Systems Command, Washington, D.C., 1 October
1987, Change 1, 1 May 1991.