SOLDERING, BRAZING, BRAZE WELDING,
The information presented in chapter 5 covered the
joining of metal parts by the process of fusion welding.
In this chapter, procedures that do not require fusion are
addressed. These procedures are as follows: soldering,
brazing, braze welding, and wearfacing. These proce-
dures allow the joining of dissimilar metals and produce
high-strength joints. Additionally, they have the impor-
tant advantages of not affecting the heat treatment or
warping the original metal as much as conventional
Soldering is a method of using a filler metal (com-
monly known as solder) for joining two metals without
heating them to their melting points. Soldering is valu-
able to the Steelworker because it is a simple and fast
means for joining sheet metal, making electrical connec-
tions, and sealing seams against leakage. Additionally,
it is used to join iron, nickel, lead, tin, copper, zinc,
aluminum, and many other alloys.
Soldering is not classified as a welding or brazing
process, because the melting temperature of solder is
below 800°F. Welding and brazing usually take place
above 800°F. The one exception is lead welding that
occurs at 621°F. Do not confuse the process of SILVER
SOLDERING with soldering, for this process is
actually a form of brazing, because the temperature used
is above 800°F.
This chapter describes the following: equipment
and materials required for soldering, the basic methods
used to make soldered joints, and the special techniques
required to solder aluminum alloys.
Soldering requires very little equipment. For most
soldering jobs, you only need a heat source, a soldering
copper or iron, solder, and flux.
Sources of Heat
The sources of heat used for soldering vary accord-
ing to the method used and the equipment available.
Welding torches, blow-torches, forges, and furnaces are
some of the sources of heat used. Normally, these heat-
ing devices are used to heat the soldering coppers that
supply the heat to the metal surfaces and thus melt the
solder. Sometimes, the heating devices are used to heat
the metal directly. When this is done, you must be
careful to prevent heat damage to the metal and the
SOLDERING COPPERS. A soldering copper
(usually called a soldering iron) consists of a forged
copper head and an iron rod with a handle. (See fig. 6-1.)
Figure 6-1.Soldering irons.