Heat treating and inspection of metals

TM 1-423
HEAT TREATING AND INSPECTION OF METALS 37-38
b. Properties.-The ultimate strength of this material is 26,000
pounds per square inch and the yield point 10,000 pounds per square
inch when in the annealed condition. These values may be raised to
48,000 and 25,000, respectively, by heat treating and aging at room
temperature. Heat treatment followed by artificial aging again raises
the values to a maximum of 58,000 and 35,000, respectively.
c. Uses.-This material in the forged and heat-treated condition is
used extensively for propeller blades, connecting rods, bearing
material, etc.
d. Annealing.-The annealing temperature is between 650 and 800
F. and cooling must be accomplished in still air.
e. Hardening.-The hardening treatment is accomplished as follows:
(1) Heat to 960o-980o F.
(2) Hold at this temperature as prescribed in table VI.
(3) Quench in cold water.
(4) Age artificially at a temperature between 2850 and 315 F. for
from 8 to 12 hours.
TABLE VI.-Soaking period for 17S, 17S Alclad, 215S, and 25S alloys
i Minimum time of soaking for
solution treatment (hours)
Thickness of material (inches) solution treatment (hours)
Air furnace Salt bath
Up to }Y32-------------------------------------- 10 10
3 2 tO 16----------- ------------------- --- 20 15
~{6 to ----------------- ---------------------- 30 20
/s to 3~6--------------------------------------- 40 20
316 to ------------------------------------- 60 20
} to --------- ------------------------ 90 30
38. Alloy 51S.-a. Composition.-This alloy is composed of 96.5
percent aluminum, 0.2 percent (maximum) manganese, 0.45 to 0.8 per-
cent magnesium, 0.15 to 0.35 percent chromium, 0.3 percent (maximum)
copper, and 0.6 to 1.2 percent silicon.
b. Properties.-The ultimate strength of this material is 16,000
pounds per square inch and the yield point 5,500 pounds per square
inch while in the annealed condition. These values are raised to 35,000
and 20,000, respectively, by heat treatment followed by aging at room
temperature and may be further increased to 48,000 and 35,000,
respectively, by artificial aging.
c. Uses.-As in the case of 25S alloy, this alloy is used principally
in the forged form for various engine parts.
35

United States. War Dept. Heat treating and inspection of metals. Washington, D.C.. UNT Digital Library. http://digital.library.unt.edu/ark:/67531/metadc96657/. Accessed February 28, 2015.