Mild steel, or soft steel, is supplanting wrought iron in many shops.
Any smith who has worked with this metal will always prefer it to
wrought iron. It is much stronger and can be bent, forged, and twisted
in all manner of shapes, without cracking or splitting. This cannot be
said of wrought iron. Therefore, when mild steel is used one is sure of
finishing his problem, provided he understands the process of heating
it. The matter of heating mild steel is the vital thing. It should
never be worked at a welding heat or below a red heat. If worked either
above or below this point it will show it by splitting or cracking
before the problem is finished. Large crystals formed by working at or
above the welding heat will cause the breaks, and internal fractures
when working at the low heat will cause the cracks. However, this can
be worked at a black red heat if the blows delivered affect only the
surface and do not penetrate to the centre. This metal lends itself to
forging better than wrought iron does. It is very good for most kinds
of forging and particularly good for making weldless rings. One of the
best problems to illustrate one of the many uses to which soft steel
may be put is the making of a weldless ring.
[Illustration: Weldless rings]
A piece of soft steel 1 in. wide, 1/4 in. thick, 4 ins. long, is the
stock used for this ring. With a centre-punch mark off 3/4 in. from
each end. (See sketch.) In each centre-punch mark punch a 1/4-in. hole
through the piece. With a hot chisel cut between these holes half way
through on one side. Turn it upside down and finish cutting through
from the other side. Now drive the chisel through, widening the slot
out. Trim up the inside of the slot. Cut away all rough edges. Upset
the piece on the anvil after heating and drive down on the ends. This
will increase the size of the hole by shortening the length and bulging
the sides out. The piece is now put on the horn of the anvil and
rounded into a ring. The ends are now trimmed off or driven down into
the thickness, as shown in the drawing. This is the method of making a
weldless ring. It is easily made out of soft steel. It would require a
very fine grade of wrought iron to do a piece of work of this kind, for
wrought iron is fibrous and unless great care is exercised in forging
it will split at the ends along the grain when opening it after the
slot is cut in.
Steel is much cheaper than wrought iron, another good reason for its
use. For the making of nuts, too, it is better than wrought iron. All
one needs to do is to cut a piece off the end of a square bar, the
proper thickness, punch a hole in it, and square it up. If wrought iron
were used, to get the same strength one would need to bend the iron
around a mandrel in the shape of a ring so that the grain of the iron
would run around the hole of the nut. Then it should be welded and
shaped into a square nut.