This gives the idea of the range of arc heating time that must be maintained for a full penetration. The arc heating time of about 17–23 s seems to yield a full penetration with a uniform bead along the weld joint for a I2 current of 200 A, respectively. However, trial 1 yields a weld with insufficient penetration but uniform reinforcement
and trial 2 yields a full penetration with non uniform reinforcement, respectively, for an I2 current of 200 A. Contrary to this, trials 9 and 10 yield full penetration. However, excess loss of material takes place due to melting of the butt ends. Consequently, the reinforcement height increases to about 3.5–4.5 mm
on the outer surface and 2–2.5 mm on the inner surface for the
9th and 10th trial, respectively, for 220 A I2 current. Further, for
the 10th trial, when excess metal is collected underneath the weld
(due to gravity), it leads to certain undesired situations such as
short circuiting the tube gap region, quenching the arc or a local
explosion, etc. Any of these situations can thus result in an unfilled
gap on the weld line on forging. Such weld specimens are likely to
fail in the ball test. Thus, only the specimens from trials 2 and 3
are considered for various non destructive tests to determine their
strength.