1993

Vilpas, Martti; Ruusila, Jouko; Kujanpää, Veli; Karppi, Risto

The report deals with the weldability of cast and rolled super duplex stainless steels (27 % Cr, 7 8 % Ni, 3 4 % Mo, 0.2 2.7 % Cu and 0,2 0,3 % N) with special reference to the mechanical and corrosion properties of welded joints. The test welds have been evaluated using metallography, mechanical testing as well as pitting and stress corrosion tests. The results indicate that the welded joints can exhibit acceptable joint properties when the type of consumable and the level of heat input are properly chosen. Matching type consumables with a heat input close to 10 15 kJ/cm yielded good results. Significantly lower heat inputs result in a lower weld metal austenite content and formation of nitrides in ferrite, resulting in reduced toughness. On the other hand, excessively high heat inputs tend to enhance various precipitation reactions, reducing HAZ toughness and corrosion resistance.