to Hadfield's manganese steel.
preheat temperature, the part must be held at this
temperature until heat has reached the core; this is
The greater the alloy content in air-hardening
commonly referred to as soaking time. All preheated
parts should be slow-cooled.
The more the air-hardening capacity of the
The need for preheating increases as the following
factors are changed:
The more complicated the shape or section of
The larger the mass being welded.
The lower the temperature of the pieces being
Base metal composition must be determined for
accurate Preheat requirements. Carbon steels and
austenitic manganese steels can be differentiated with
The lower the atmospheric temperature.
the use of a magnet. Carbon steels are magnetic;
austenitic manganese steels are not. (Austenitic
The smaller the weld rod diameter.
manganese steel will become magnetic after being
workhardened so a magnetic check should be made in
The greater the speed of welding.
a non-worked area. ) Cast iron can be determined by a
spark when a metal-working chisel is applied to the
The higher the carbon content of the steel.
base metal; cast iron will chip or crack off; cast steel
The higher the manganese content in plain
carbon or low alloy steels. This does not apply