Introduction cont'd

DOE-HDBK-1132-99

metallurgy (which is different from the chemistry), including metallurgical phases,

local composition variations, nonmetallic inclusions, etc., and

fabrication processes, such as heat treatment, machining, pickling, bending, and

welding.

Not all metals are susceptible to all the age-related mechanisms identified above. The

susceptibility depends on the particular alloy, metallurgy, processing parameters, and

environments involved. Therefore, an acceptable metallic selection process considers

the following:

all possible degradation and failure modes in addition to mechanical failures,

metallurgy and fabrication processes,

availability of adequate data support and service experience for the specific

application, and

Nonmetallic materials are susceptible to thermal, cyclic, chemical, mechanical, humidity,

and radiation age-related degradation. An acceptable nonmetallic material selection

process considers, at least the following:

thermal properties, including temperature stability;

chemical properties, stability/resistance to chemicals;

electrical properties;

physical properties, including water/moisture absorption, odor;

mechanical properties;

thermosetting or thermoplastic;

flammability rating; and

optical properties, transparent, translucent, or opaque.

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