Submerged arc welding (SAW) is used widely in the manufacturing industry for
fabricating large diameter pipes, wind turbine towers, and pressure vessels due mainly to its
ability to combine high weld quality with high deposition rates and ease of automation. The
quality of weldments produced using the SAW process is affected by such variables as welding
current, arc voltage, welding speed and electrode stick-out. Therefore, the selection of
appropriate parameters in SAW is essential, not only for optimizing the welding process in order
to maintain the highest level of productivity, but also to obtain the most desirable mechanical
properties of the weld.
The effect of SAW welding speed and current on the impact and tensile properties of
A516 Gr. 70 steel was investigated using hardness measurements, tensile testing, Charpy impact
testing and optical microscopy. SA516 Gr.70 plates measuring 915 mm x 122 mm x 17 mm
were submerged arc welded using two welding currents (800 A and 850 A) and four travel
speeds (5.9, 9.3, 12.3 and 15.3 mm/s). The results showed that the hardness of the coarse-grained
heat-affected zone (CGHAZ) and the weld metal increased with travel speed. The yield and
tensile strengths of SA516 Gr.70 joints were within the same range as those of the parent metal
because all test specimens broke in the parent metals. Also, the fracture strain increased with
travel speed. The impact toughness of the parent metal (PM) was higher than that of the weld
metal (WM), but lower than that of the heat-affected zone (HAZ).