the melting point will, therefore, have the largest grain size and the
least strength. Those parts that have not suffered any great rise in
temperature will be practically unaffected, and all the parts between these
two extremes will be weaker or stronger according to their distance from
the weld itself. To restore the steel so that it will have the best grain
size, the operator may resort to either of two methods: (1) The grain may
be improved by forging. That means that the metal added to the weld and the
surfaces that have been at the welding heat are hammered much as a
blacksmith would hammer his finished work to give it greater strength. The
hammering should continue from the time the metal first starts to cool
until it has reached the temperature at which the grain size is best for
strength. This temperature will vary somewhat with the composition of the
metal being handled, but in a general way, it may be stated that the
hammering should continue without intermission from the time the flame is
removed from the weld until the steel just begins to show attraction for a
magnet presented to it. This temperature of magnetic attraction will always
be low enough and the hammering should be immediately discontinued at this
point. (2) A method that is more satisfactory, although harder to apply, is
that of reheating the steel to a certain temperature throughout its whole
mass where the heat has had any effect, and then allowing slow and even
cooling from this temperature. The grain size is affected by the
temperature at which the reheating is stopped, and not by the cooling, yet
the cooling should be slow enough to avoid strains caused by uneven
contraction.

After the weld has been completed the steel must be allowed to cool until
below 1200 Fahrenheit. The next step is to heat the work slowly until all
those parts to be restored have reached a temperature at which the magnet
just ceases to be attracted. While the very best temperature will vary
according to the nature and hardness of the steel being handled, it will be