In all cases, weld surfaces appear
stable, with none of the weld spatter normally associated with welding
FIGURE 4 shows a scanning electron micro-
scope (SEM) image of the fracture surface
of a phosphor-bronze-to-stainless-steel
weld. In this case, the phosphor-bronze side
of the weld interface has been examined
after strength testing to failure. In this case,
the iron-rich (green-colored) weld metal is
seen to have penetrated into and is sur-
rounded by the phos-
phor bronze, which
has failed in ductile
shear. Some pores
are seen at the phos-
The high joint
strength of low carbon
steel when welded to
needs more investigation, but all of the materials welded to low car-
bon steel produced
high joint strengths.
Phosphor bronze is
widely used as a high-strength alternative to
copper and, as such,
the ability to weld this
material to ferrous
metals is important.
The smooth top bead
shown in FIGURE 5a
again suggests a very
stable keyhole weld.
The weld failure at the
interface (FIGURE 5b)
shows ductile failure
of the copper-rich layer
that has been trans-
ferred to the underlying
stainless steel surface.
to stainless steel is
FIGURE 5. The surface of a phosphor-bronze-to-stainless-steel weld (a), and the same
weld with ductile interface failure at 500X (b).
FIGURE 4. A scanning electron microscope image showing a 302
stainless-steel-to-phosphor-bronze weld at 600X magnification.