Abstract :
Resistance microwelding of 316L stainless
steel to Pt wire has been performed. The interfacial
metallurgical phenomena, joint breaking force and
fracture mode were investigated using scanning electron
microscopy, energy-dispersive X-ray spectroscopy
and tensile-shear testing. The results showed that a
solid-state bonding was achieved at the interface when
the welding current was low and/or the weld time was
short, whereas a bonding with fusion of materials was
observed at high welding current. Melting of the
stainless steel was more significant than that of the Pt
wire. The amount of melted materials and bonded area
increased with increasing welding current and/or weld
time. At a low welding current, e.g., 500 A, all the
joints fractured at the interface and the joint breaking
force rapidly increased when weld time prolonged
from 2 ms to 10 ms owing to increased bonded area. At
a medium welding current, e.g., 750 A, the joints
demonstrated different fracture mode, e.g., at the
interface, a mixed failure at the interface and in the Pt
wire as well as completely within the Pt wire, as the
weld time increased. On the other hand, at a high
welding current, e.g., 1,000 A, the stainless steel was
greatly melted and softened into which the Pt wire
penetrated and all the joints fractured in the Pt wire.
The joint breaking force first increased with increasing
weld time and subsequently decreased after reaching a
peak value. The effects of materials properties on
dissimilar materials resistance welding process were
also discussed.
