Three weld metals containing Mn, Mo and Ni and one containing Mn and M
o were obtained using the submerged arc welding process. Cleavage/fibr
ous transition temperatures of the weld metals were determined based o
n crack opening displacement (COD) vs., temperature curves and fractur
e surface examination. Three main factors affecting cleavage/fibrous t
ransition temperature of the weld metals, i.e., cleavage strength, yie
ld stress and stress intensification of specimens with a crack, were i
nvestigated. The cleavage strength was found to be influenced by the a
verage area of M-A constituents. There is almost no difference in the
yield stress for all four weld metals. Lower stress intensification ha
s been achieved for the weld metals containing Mn, Mo and Ni as compar
ed with that containing Mn and Mo. As a result, the transition tempera
tures of the weld metals containing up to 0.36% of nickel are signific
antly lower than that of the Mn-Mo weld metal. An attempt was made to
predict the transition temperatures, and the prediction is in agreemen
t with the experimental results.