Effect of temperature and strain rate on cavitation in a superplastic duplex stainless steel

The effect of temperature and strain rate on cavitation during superplastic deformation of a duplex stainless steel has been studied at 1223 K and 1253 K for initial strain rates ranging from 2 x 10(-4) s(-1) to 2 x 10(-3) s(-1). The cavitation was analyzed quantitatively for a specifically developed image processing technique that allows an accurate determination of the volume fraction and size distribution of the voids. The results show that increasing temperature and/or decreasing strain rate cause a more homogeneous deformation of the specimen characterized by a uniform size and distribution of the cavities. The increase of the strain rate results in an increase in cavity volume fraction related to more cavity nucleation and interlinkage. This reflects the lack of accommodation process during the mechanism of grain boundary sliding. (C) 1997 Acta Metallurgica Inc.