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

The relations between the migration of the delta/gamma interface boundary a nd the growth of austenite as a function of aging treatment in SAF 2205 dup lex stainless steel were investigated in the present study. The migration o f tilt: delta/gamma interface boundary into the ferrite phase region result ed from the nucleation and growth of M23C6 carbides with patterns of "lamel lar" and "larva", having a cube-cube orientation relationship with the aust enite. The growth of secondary austenite, which is mainly induced by chromi um 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 betwe en the a phases. (C) 1999 Elsevier Science S.A. All rights reserved.