and scanning electron microscopy (SEM) studies. Three
etching procedures were followed to clearly delineate
the microstructrual constituents present in the weldments.
In the first, samples were etched with 4 pct Nital
solution for 5 seconds. The second was carried out using
10 pct Picral solution for 90 seconds for better delineation
of prior austenite grain boundaries. The third
etching method was used to examine the presence of
RA in the microstructure. In this method, samples were
etched for 15 seconds with 4 pct Picral followed by 30
seconds etching in 1 pct sodium metabisulfite solution in
water. This etching procedure changes the colors of the
RA/martensite into bright whitish blue, bainite into
brown, and allotriomorphic ferrite into a tan color.[7] The
samples were subsequently analyzed using optical
microscopy.
Scanning electron microscopy was performed using
a JEOL* JSM 6500F field emission gun (FEG) scanning