Figure 5-12. Identification markings
(3) Markings. A further test for identifying metals is to check for markings such as the
manufacturer's part or specification numbers. Check such data against part numbers or the group
numbers shown in the TO 00-25-113 series, or the alloy group and material specifications.
(4) Common use. When a specimen cannot be identified by part or specification numbers,
examine its physical appearance and determine its possible common use. Check the color of the metal.
Is the color silver, like polished aluminum or magnesium; yellow, like brass or gold; gray, like zinc or
lead? The metal color may indicate which alloys and elements are present.
b. Mechanical Testing. If a metal cannot be positively identified by visual examination, see if it
is attracted by a magnet. Perform a spark test if the metal is magnetic.
(1) Magnetic testing. To determine whether the specimen is attracted by a magnet, the
magnet should be free-swinging from a chain, ring, or string. Metals commonly attracted by a magnet
are iron, steel, or iron-based alloys containing nickel, cobalt, or chromium. However, there are
exceptions to this general rule. This test can serve only as an initial step in identifying a specimen and
never as a final test. Strong-magnetic metals include pure iron, nickel, and cobalt; iron-nickel-cobalt
alloys; and alnico