δ-Ferrite stability in the heat affected zone during welding of steel 17247

The conditions of formation and decay of δ-ferrite in the heat affected zone near welded joints of CSN 17247 steel were examined. The dependence of the ferrite content on the annealing temperature was studied on laboratory samples over the 950 to 1200 degC range using a short-time arrest of 1 to 15 min. Other tests simulating real welded joints, obtained by the WIG method, were also carried out. Short-term heating for 15 min at 1100 to 1150 degC brought about an increase in the δ-ferrite content, whereas short-term annealing at temperatures lower than 1100 degC was associated with a decrease in the amount of the ferritic phase. In the heat affected joint zone and in the weld material, the δ-ferrite content was found higher than in the base material. CSN 17247 steel proved not to be prone to the development of cracks during welding. (Z.M.). 5 figs., 2 tabs., 11 refs