Influence of long time ageing on ductility and toughness in the stainless steel 310 in the presence of banded microstructure

Abstract

During service at elevated temperatures extensive formation of particles can take place that can have a
dramatic influence on mechanical properties. Precipitation of ?-phase and M23C6-carbides have been studied
both experimentally and with thermodynamic modelling for 25Cr20Ni austenitic stainless steels (AISI 310) at
800 ºC for up to 5000 h. Previous work has demonstrated that the modelling could describe the nucleation and
growth satisfactory. After long term ageing the particles form bands in the microstructure. In the present paper
the influence of these bands on ductility and toughness at room temperature is analysed. For this purpose
previously developed models for ductility and toughness are utilised. Model values for banded and non-banded
microstructures have been generated for casts of 310 in fine and coarse grained conditions with 0.04 and
0.12%N. The model values show that in the coarse grained condition, no reduction in ductility and toughness
can be expected in the banded microstructure. In the fine grained condition a modest reduction is predicted.