Experiments were conducted in three different groups with the
aim of investigate the effect of t8/5 determining the cooling rate
on the toughness properties. In the first group of experiments,
the samples A–C were derived with alteration of the numbers of
used weld electrodes in internal and external welding, the electrical
welding parameters and the welding speeds, but t8/5 values
were the same because of the equal heat input of internal and
external weld seams. The welding parameters of the sample A
are given in Table 4, which was welded with a welding speed of
2.0 m min−1, employing three electrodes in internal welding and
two electrodes in external welding. The welding parameters of the
sample B are given in Table 5, which was welded with a welding
speed of 1.5 m min−1, employing two electrodes for each internal
and external welding, with the heat input and t8/5 remaining fixed.
The welding parameters of the sample C are given in Table 6, which
was welded with a welding speed of 1.2 m min−1, employing two
electrodes in internal welding and only one electrode in external
welding. Table 7 shows t8/5 values of internal and external weld
seam of the samples A–C, hardness measurement values and the
results of notch impact test at −20 ◦C. In the case that, in the SAW
being applied, the heat input gained was the same despite different
electrical welding parameters, welding speeds and numbers
of weld electrodes, the mechanical properties of the welded construction
were investigated. The macro-images of weld seam of the
samples