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|  MIL-S-85419 (AS)
subject to repeated loads, wherein stress concentration factors
are governing, shall be demonstratably consistent with the design
fatigue life of the parts in the planned operating environment.
Surface roughness limits and limiting criteria for allowable
flaws shall be established for approval by the verifying
Alternately, the surface roughness shall not exceed
activity.
125 RMS and there shall be no flaws such as tool marks deeper
than 0.0002 inch. Such limits for parts critical in low cycle
fatigue shall be separately identified.
3.5.1.3.7 Heat Treatment. Heat treatment of aluminum alloys
shall be in accordance with the material specification and
MIL-H-6088. Steels shall be heat treated in accordance with the
material specification and MIL-H-6875. Precautions shall be
taken to minimize warpage during heat treatment. Steel parts
which require straightening after hardening to 200,000 psi or
below may be cold straightened provided a stress relieving heat
treatment is subsequently applied.
Straightening of parts hardened to tensile strengths above
200,000 psi shall be accomplished at a temperature within the
range from the tempering temperature to 50F (28C) below
tempering temperature.
3.5.1.3.8 Welding. Welding joints shall be in accordance with
applicable welding specifications. Welded assemblies involving
steels and section sizes which transform on air cooling to
microstructure other than martensite shall be normalized or
otherwise processed to equivalent hardness in the weld areas.
When welding air hardening steels, appropriate precautionary
measures, including preheating interpass temperature control and
post heating shall be applied.
To avoid the possibility of stress corrosion and fatigue
damage in welded primary structural components; the structures
shall be so designed that the weld bead material is accessible
for machining during manufacture. In addition, welded primary
structural components shall be stress relieved after all welding
is completed.
3.5. 1.3.9 Corrosion Protection. Metals which do not possess
adequate corrosion-resisting characteristics shall be protected
to resist corrosion from dissimilar metal combinations; moisture,
salt spray and high temperature deterioration as applicable. The
protection of the equipment from corrosion shall be in accordance
with MIL-F-7179. Dissimilar metals in immediate contact shall be
avoided. Where use of metals in immediate contact cannot be
avoided, they shall be insulated. This has particular reference
to dissimilar metal contacts defined in MIL-STD-889.
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