Summary form only given. The authors present an interim report on the effect of various alloying additions in the weld deposit and base material on the precipitate dispersion and stability, the microstructure and toughness of microalloyed constructional steels, in both the as-welded as well as welded and stress-relieved conditions. Materials investigated include welded AlTi, AlTiV, AlTiNb and AlV steels with the use of electrodes either with or without Mo additions