Analysis of the creep strength of a low-carbon AISI 304 steel with low-Σ grain boundaries

The creep response of an AISI 304L steel with a large proportion of low-Σ grain boundaries was investigated by means of constant-load creep tests at 853 and 923 K. Microstructural studies revealed an extended precipitation of intragranular carbides given sufficiently long times of exposure during creep. The minimum creep rate dependence on applied stress was described by a power law with stress exponents of 10.4 and 15.6 at 923 and 853 K, respectively. Comparison between the creep data obtained in the present study and data from the literature indicates that grain boundary engineering is an effective method to increase creep response; this behaviour was interpreted in terms of enhancement of intragranular precipitation of strengthening carbides, the intergranular precipitation being substantially suppressed by the nature of grain boundaries.