Pulsed Current Welding (PCW) was introduced in the late 1960s as a variant of
Constant Current Welding (CCW). PCW process has many specific advantages over CCW.
These include enhanced arc stability, increased weld depth/width ratio, narrower Heat
Affected Zone (HAZ) range, reduced hot crack sensitivity, refined grain size, reduced porosity,
low heat input, low distortion, controlled weld bead volume, less absorption of gas by weld
pool and better control of the Fusion Zone (FZ) [1-8]. Pulsed current welding technology
has been widely used in fabrication of high pressure air bottles, rocket motors, and structures
in aerospace applications, such as aircrafts, rockets and missiles. Switching
between predetermined high and low levels of welding current can be used to produce pulsed
current gas tungsten arc welds .
Very few reports have been published on pulsed current GTAW of alloy steels.
Previous investigations have proved that, during pulsed current GTAW welding, a higher
pulse frequency at smaller pulse spacing can enhance the energy density of the welding heat
source, thereby reducing the angular distortion of stainless steel weldments . So far, the
studies reported were on the use of pulsed current welding to study the effect of pulsed
current, shielding gas composition, weld speed and bead shape, on the incidence of welding
defects and joint strength using alloy sheets of 5,083 type  , angular distortion in stainless
steel weldments of 304 and 310 type , and on the microstructure  and weld bead
geometry . This prompted us to study the effect of pulsed current on welding characteristics of
alloy steel, as used in aerospace applications. In the present work, 15CDV6 alloy steel
weldments using pulsed and non-pulsed current GTAW have been examined and the
macrostructure and microstructure development in Fusion Zone (FZ) and Heat Affected Zone (HAZ) of
the weldments have been studied.