Ratchetting behavior of advanced 9–12% chromium ferrite steel under creep-fatigue loadings

A local extrapolation based calculation reduction method for the application of constitutive material models for creep fatigue assessment

“…However, this assumption is not valid under certain conditions [9]. To fix the problem, a plausibility check will be carried out after every extrapolation step, which is shown in Fig.…”

Characterization and modeling of the ratcheting behavior of the ferritic–martensitic steel P91

“… Austenitic steels such as 316L [9][10][11], 316LN [12], 304 [13][14][15][16][17][18][19][20], 304L [21], 304LN [22] (304L means "low carbon", 304LN means "low carbon and high nitrogen" [23]);  Ferritic steels [24][25][26][27][28];  Carbon steels (CS) 40Cr [29], 42CrMo [18,30,31], 16MnR [32], X42 and X56 [33], 20 CS [34,35], 45 CS [36];  Other steels such as SA333C-Mn steels [37], Interstitial-Free Steel [38];  Other metallic materials, such as zirconium alloys [39], pure titanium [40], titanium alloys [41], NiTi shape memory alloy [42,43];  Ceramic matrix composites [44]; and  Polymers such as polytetrafluoroethylenes (PTFE) [45], polypropylene [46], polyacetal/polyoxymethylene [47], epoxy resin [48] etc.…”

“…In most ratcheting research [3-5, 9, 14, 16, 24, 26, 30, 36], minimum stress in each hysteresis loop was compressive. On the contrary, uniaxial ratcheting tests with tensile minimum stresses were carried out on ferritic steel X12CrMoWVNbN10-1-1 with various hold times and stress ratios at a temperature of 600 °C [25,27]. Because the minimum stress in each cycle was tensile, the hysteresis loops were always within the tensile range.…”

“…The so-called shakedown behavior of ratcheting was observed on specimens subjected to a relatively long hold time (i.e. 5 and 20min), which meant the partial inelastic strain formed during the stress-changing process of each cycle continuously decreased until no ratcheting was observed [25,27].…”

“…On the other hand, when the hold time was less than 5min, the total accumulated strain was mainly composed of the increased ratcheting strain owing to the inelastic creep recovery. For longer hold times (10, 20 or 30min) however, the accumulated creep strains were the controlling mechanism of deformation [25,27].…”