METAL PROPERTIES, CHAR, USES, AND CODES - OD1643 - LESSON 1/TASK 2
(3) Wrought Iron. The appearance of wrought iron is the same as
that of rolled low-carbon steel discussed in paragraph 3b(4)(b),
below.
(4) Low-Carbon Steel. The appearance of low-carbon steel depends
upon its method of preparation rather than on its composition.
(a) Cast Steel.
Cast steel
has
a
relatively
rough,
dark
surface, except where machined.
(b) Rolled Steel.
Rolled steel has fine surface lines running
in one direction.
(c) Forged Steel. Forged steel is usually recognizable by its
shape, hammer marks or fins.
(5) High-carbon Steel. High-carbon steel may be identified by its
unfinished surface, which is dark gray.
These steels can be worked
to a smoother finish than the less costly low-carbon steels.
(6) Cast Steel. The surface of cast steel is brighter than cast
or
malleable
iron
and
sometimes
contains
small
bubblelike
depressions.
(7) Steel Forgings. Steel forgings have a smooth surface. If the
forgings have not been finished fins, caused by metal squeezing out
between the forging dies, will be evident.
If it is a finished
forging, the area from which the fins have been removed will be
noticeable.
Unless these forgings have been properly cleaned, they
will be covered with a reddish-brown or black scale.
(8) Distinguishing Between Steel and Aluminum or Lead.
Steel is
distinguished from aluminum or lead by the application of a copper
sulfate solution.
This solution is spread on the surface of the
metal with a small brush or with the end of a clean cotton rag. The
copper sulfate does not react with aluminum or lead, but it leaves a
copper coating on the surface of steel.
c.
Appearance of Nonferrous Metals.
(1) Aluminum. Aluminum is identified by its light gray to silver color
and light weight. When polished it is very bright, becoming dull when it
is oxidized. Rolled and sheet aluminum materials are usually pure metal.
Castings are alloy of aluminum with other metal, usually zinc, copper,
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