Effect of isothermal treatment of SAF 2205 duplex stainless steel on migration of δ/γ interface boundary and growth of austenite

The relations between the migration of the delta/gamma interface boundary and the growth of austenite as a function of aging treatment in SAF 2205 duplex stainless steel were investigated in the present study. The migration of tilt: delta/gamma interface boundary into the ferrite phase region resulted from the nucleation and growth of M23C6 carbides with patterns of "lamellar" and "larva", having a cube-cube orientation relationship with the austenite. The growth of secondary austenite, which is mainly induced by chromium depletion arising from carbide and a phase formation, has occurred in of three different ways; (i) the coupled lamellor growth, (ii) only austenite growth leaving "larva" typed carbides and (iii) the bulged austenite between the a phases. (C) 1999 Elsevier Science S.A. All rights reserved.