Influence of prior cyclic hardening on high temperature deformation and crack growth in type 316L (N) stainless steel

Self-consistent modelling of cyclic loading and relaxation in austenitic 316H stainless steel

“…Specimen A experiences the fastest creep rate while the creep rate of Specimen C is slightly lower. The reason behind this is the hardened state of Specimen C as a result of prior cyclic history, agreeing with Joseph et al [13]; dislocation motion in Specimen C would be more difficult due to the higher dislocation obstacle density and thus, once an equilibrium is reached between hardening and static recovery, the strain rate would be lower [41]. The lowest steady-state strain rate is both recorded experimentally and predicted via the SCM for Specimen B.…”

“…The SCM predictions capture well the trend in experimental results; the largest amount of creep strain is accumulated during the dwell in Specimen A and the least amountin Specimen B with the creep response of Specimen C in between. Both Specimens B and C demonstrate lower amounts of creep strain accumulated during primary creep compared to Specimen A, agreeing with observations made in [41,42,67,72]. Although the model prediction overestimates the accumulation of creep strain with time for the Type A history, the difference with experimental data is by approximately a factor of two which is acceptable based on the observations of scatter in deformation response of Type 316 stainless steel across different and similar casts [69].…”

“…It is also observed that this reduction in creep strain is manifested in the decrease of both primary and secondary creep rates, as described by Kikuchi and Ilschner [42]. Studies by Ajaja and Ardell [43] and Fookes et al [41], however, demonstrate that pre-straining can have little or no effect on the secondary creep strain rate which is contradictory to the observations reported in [42].…”

“…Understanding the effects of prior cyclic plasticity on subsequent creep response during strain-or stresscontrolled dwells is of importance to assessing the deformation and damage response of components in nuclear power plants which undergo complex thermo-mechanical loading histories [41]. Previous studies of creep-fatigue interactions in austenitic stainless steel demonstrate that the amount of creep strain accumulated during a dwell after pre-straining decreases significantly as a result of the cyclic hardening of the microstructure [13,42].…”

The effect of prior cyclic loading variables on the creep behaviour of ex-service Type 316H stainless steel

“…Tests have been conducted on various grades of type 316H stainless steel using combinations of tension and torsion for loading of the prior cyclic loading or creep phases by Wei and Dyson [1] and Murakami et al [2] in type 316 stainless steel, and with both prior cyclic loading and creep conducted under uniaxial conditions by Tavassoli et al [3], Fookes et al [4], Skelton and Horton [5], Rezgui [6,7] and on behalf of EDF Energy by Spain [8], Alstom, and Binda [9].…”