When molten metal is placed upon cooler surfaces
the result is not a weld but merely a sticking together of the two parts
without any strength in the joint.
FLUXES
Difficulty would be experienced in welding with only the metal and rod to
work with because of the scale that forms on many materials under heat, the
oxides of other metals and the impurities found in almost all metals. These
things tend to prevent a perfect joining of the metals and some means are
necessary to prevent their action.
Various chemicals, usually in powder form, are used to accomplish the
result of cleaning the weld and making the work of the operator less
difficult. They are called fluxes.
A flux is used to float off physical impurities from the molten metal; to
furnish a protecting coating around the weld; to assist in the removal of
any objectionable oxide of the metals being handled; to lower the
temperature at which the materials flow; to make a cleaner weld and to
produce a better quality of metal in the finished work.
The flux must be of such composition that it will accomplish the desired
result without introducing new difficulties. They may be prepared by the
operator in many cases or may be secured from the makers of welding
apparatus, the same remarks applying to their quality as were made
regarding the welding rods, that is, only the best should be considered.
The flux used for cast iron should have a softening effect and should
prevent burning of the metal.
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