ABSTRACT
This paper presents the optimization of welding parameters of electron beam welded
joint of dissimilar materials namely AISI 430 ferritic stainless steel and AISI 1020 low
carbon steel (0.21% C.). Three main welding parameters were investigated. These
parameters are welding current, focusing current and welding speed. The
optimization was based, from one hand, on microstructure analysis of both bead and
heat affected zones, using optical and scanning electron microscopes, and, from the
other hand, the evaluation of tensile, impact, and micro-hardness mechanical
properties. The results of the investigation showed that, an optimum welding current
of 24 mA, a focusing current of 875 mA, and a welding speed of 8mm/s at a working
distance 100 mm can provide uniform welding bead with full penetration, without
undercuts and a narrow width of HAZ. Moreover, they can secure a tensile failure
outside the joint, in the base metal (low carbon steel) satisfying a tensile strength of
about 431 MPa. Furthermore, the impact resistance of the joint was found to provide
about 160 J/cm2 (hammer against the root of bead) and about 60 J/cm2 (hammer
against the face of bead). The hardness distribution along the joint from the stainless
steel side to the low carbon steel side through the bead and HAZ was determined,
and indicates that, a maximum hardness of about 380 HV was obtained in the center
of the bead. This value is higher than the obtained hardness values of both the ferritic
stainless steel and low carbon steel.