Abstract

Structural components are regularly exposed to cyclic thermal stresses which can induce plastic deformation within them. The accumulation of plastic deformation will eventually lead to failure of the component. The creep behaviour a material exhibits depends upon the magnitude and sign of the prior loading the material was subjected to. This idea was investigated by conducting tests on a section of 316H stainless steel header at 550°C. Both negative and positive plastic strain were applied upon loading followed by load controlled creep to investigate the influence of prior loading upon the accumulation of creep strain. These tests resulted in more creep strain being accumulated after compressive prior loading as opposed to tensile prior loading. This result is significantly influenced by intergranular strains which come from elastic and plastic anisotropy. The experimental results have been compared to the results of an existing crystal plasticity finite element (CPFE) model and there is good agreement between the two sets. Validation of the CPFE model is important for understanding the behaviour of 316H and being able to accurately predict the hysteresis loop this material produces which can provide vital information when conducting life assessments.

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