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MIL-V-81995(AS)
b.
Precipitation hardening semi-austenitic grades
shall not be used in applications which require extended exposure to
temperatures in the 750 -900F (399 -482C) range.
c.
The use of heat treated 431 or 19-9DL steel
shall be subject to approval by the qualifying activity.
d.
The use of 17-4PH stainless steel aged below
H1025 shall be subject to approval by the qualifying activity.
Magnesium or its alloy shall not
Magnesium alloy.
3.5.1.3.3
be used.
Castings.  Castings shall be in accordance with MIL-
3.5.1.3.4
C-6021 and shall be classified Class lB, grade C or higher. Aluminum
alloy castings shall be in accordance with MIL-A-21180. Defects not
materially affecting the suitability of the castings may be repaired at
the foundry or during machining by peening, impregnation, welding, or
other methods acceptable to the procuring activity.  Inspection of
repaired castings shall be governed by quality control techniques subject
to the approval of the qualifying activity.
Stress corrosion embrittlement factors.  To prevent
3.5.1.3.5
premature failures caused by stress corrosion or hydrogen embrittlement,
the  design  and  method  of  manufacture   of parts of titariiiim and steel
heat-treated to tensile strengths above 220,000 psi or of bare high
strength aluminum alloys and the techniques by which they are assembled
and installed shall be such that sustained or residual surface tensile
stresses and stress concentrations are minimized.  Practices, such as:
the use of press or shrink fits; taper pins, clevis joints in which
tightening of the bolt imposes a bending load on the female lugs; and
straightening or assembly operations; which result in sustained or
residual surface tensile stresses shall be avoided.  In cases where such
practices cannot be avoided, corrective practices such as stress relief
heat treatment, optimum grain flow orientation, peening (shot or rotary
flat) or similar surface working shall be used to minimize the hazard of
stress corrosion or hydrogen embrittlement damage.  In no case shall
sustained or residual surface tensile stresses in these materials exceed
50% of the material specification minimum yield strength in the longitudinal
grain flow direction, 35% of the minimum yield strength in the long
transverse direction and 15% of the minimum yield strength in the short
transverse direction, except that for materials of demonstrated high
resistance to stress corrosion cracking, such as 7075-T73 aluminum
8

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