Effects of Amplitude-History and Temperature-History on Multiaxial Cyclic Behavior of Type 316 Stainless Steel

Abstract

The effects of the history in strain-amplitude and temperature variation on the multiaxial cyclic behavior of type 316 stainless steel were discussed by performing a series of total-strain controlled cyclic tests under uniaxial tension-compression and circular strain paths. Constant strain rate of 0.2 percent/min was specified throughout the tests. The effects of strain amplitude history were examined by changing the strain amplitude between 0.2 percent and 0.4 percent (step-up and step-down tests) at room temperature, 400°C and 600°C. For temperature history dependence tests, the temperature was changed between 200°C and 600°C, 400°C and 600°C, 500°C and 600°C, by specifying a constant strain amplitude of 0.3 percent. It was observed that for the step-up change in strain amplitude the prior cycle showed apparently no influence on the subsequent cyclic accommodation for the uniaxial and the multiaxial cycles at room temperature, 400°C and 600°C. For the decrease in strain amplitude, however, the definite effect of the prior cycle was observed at 400°C, while at higher temperature it disappeared. The effect of the temperature history, on the other hand, appeared only in the case of the temperature-decrease during the uniaxial cycle.

Applied and engineering versions of the theory of elastoplastic processes of active complex loading part 2: Identification and verification

“…To estimate the accuracy of the proposed model, we use the experimental results in [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] and represent maximally widely (form the data found in the literature) the class of active combined loading processes Q. We also consider processes close to Q to specify the boundaries of the class of admissible processesQ.…”

“…In [12,28], the following results of experiments with stainless steel S316 in deformation along trajectories of the form = r are given: to a circle of another radius occurs along the axis 1 ). The parameters of the function Φ( ) (3.17) are determined from the experimental data of simple loading [12,29] and are given in the last row in Table 1.…”

“…The value q c = 2.3 was obtained in experiment (1) (according to (3.13)-(3.15), this value was obtained by multiplying the strengthening coefficient σ * (r)/Φ(r) ≈ 1.8 by λ /r, because = r = 0.004 < λ = 0.005 in this experiment). Figure 24 shows that the modeling of the dependence σ ∼ s (no experimental data for the angle ϑ are given in [12,28]) in the processes with constant or increasing r is quite satisfactory; the greater level of the error for small values of r can be explained by the simplest (linear) dependence of the strengthening coefficient, which was used in (3.14), on r/ λ ; there is no good description of the behavior of σ with decreasing r, but this process does not belong to the classQ. The experimental and theoretical results presented in Section 4, which are processes of deformation along two-and many-link trajectories with different lengths of links and break angles, plane curvilinear segments of different constant and variable curvature, and the three-dimensional helical segments of different curvature and twist, permit using the model (1.1), (3.1), (3.2), (3.12), (3.4), (3.10), (3.11), (3.13), (3.14) to describe the class of processes of arbitrary active loading of class Q (and of classQ with a greater but quite acceptable level of error, see Section 2).…”

Influence of the stacking fault energy and temperature on the prestrain memory effect of face centered cubic metal submitted to cyclic loadings

“…In case of a tensile PH, the memory effect appears if the prestrain is larger than 20% [2][3][4]. For stainless steels of low SFE, Murakami et al [5] described an increase in flow stress in fatigue if the samples were previously submitted to a PH with larger strain amplitude than during fatigue cycles. However it seems that this effect occurs if the prestrain amplitude is larger than 0.4%.…”