Two groups of HSLA steels produced by controlled rolling are being studied, comparing their properties as plate, tube and after welding during fabrication including the heat affected zone (HAZ). One group contains Nb and Cr and the other Nb, Cr and Mo. The Mo addition promotes an increase in the volume fraction of bainite for low carbon content (0.04-0.07 wt%) steels. The alloys were evaluated considering the microstructure-mechanical properties relationships, comparing the values determined with those of the API 5L standard, taking into account the impact transition temperature (TT), carbon equivalent (CE), and the percentage of martensite-austenite (MA) constituent. The granular bainitic microstructure obtained showed low sensitivity to the UOE fabrication process, where the plate is cold pressed into "U" and to "O" formats sequentially, followed by submerged arc welding and the tube is then expanded (E). This fabrication sequence, can lead to a loss of strength due to the Bauschinger Effect. The transition temperature of the steel, after forming, was reduced, and the transition temperature of the HAZ for both systems was lower than that of the plate itself indicating a gain in low temperature toughness. The observed increases in hardness and TT were correlated with increased CE and MA volume fraction.