Processing through the application of severe plastic deformation (SPD), as in equal-channel angular pressing (ECAP), provides an opportunity for achieving exceptional grain refinement to the submicrometer or even the nanometer level. After SPD processing, these materials may be conveniently used for evaluating the effect of a reduced grain size on the creep behaviour at elevated temperatures under testing conditions of constant load or constant stress. This report provides an overview of the creep properties of ECAP-processed metals with an emphasis on the microstructural characteristics developed by SPD, on their thermal stability and especially on the creep mechanisms that control their flow behaviour. For convenience, these properties are generally compared with the creep behaviour of coarse-grained (CG) samples of the same materials tested under identical conditions.

Cast nickel-based superalloys INC713 LC, B1914 and MAR-M247 are widely used for high temperature components in the aerospace, automotive and power industries due to their good castability, high level of strength properties at high temperature and hot corrosion resistance. The present study is focused on the mutual comparison of the creep properties of the above-mentioned superalloys, their creep and fracture behaviour and the identification of creep deformation mechanism(s). Standard constant load uniaxial creep tests were carried out up to the rupture at applied stress ranging from 150 to 700 MPa and temperatures of 800–1000 °C. The experimentally determined values of the stress exponent of the minimum creep rate, n, were rationalized by considering the existence of the threshold stress, σ₀. The corrected values of the stress exponent correspond to the power-law creep regime and suggest dislocation climb and glide as dominating creep deformation mechanisms. Fractographic observations clearly indicate that the creep fracture is a brittle mostly mixed transgranular and intergranular mode, resulting in relatively low values of fracture strain. Determined main creep parameters show that the superalloy MAR-M247 exhibits the best creep properties, followed by B1914 and then the superalloy INC713 LC. However, that each of the investigated superalloys can be successfully used for high temperature components fulfils the required service loading conditions.