Heat affected zone properties of 2 1/4 Cr 1 Mo steels with and without niobium and vanadium stabilization

To explain ductility problems in the heat affected zone of niobium stabilized 2 1/4 Cr-1 Mo steels, some comparative testing has been made on three commercial steels, one non-stabilized and the two others stabilized with niobium and niobium-vanadium. The first part of the work which is still in progress is reported. The shift of Charpy V transition curves has been studied according to the heat treatment of the steels; some of these heat treatments have been obtained by simulating the temperature cycles of the heat affected zone during welding. Hot ductility tests have also been performed on a weld thermal simulator. Metallographic examinations have been made on real welds and simulator specimens. (author)