In-Phase and Out-of-Phase Axial-Torsional Fatigue Behavior of Haynes 188 Superalloy at 760°C

Abstract

Isothermal, in-phase and out-of-phase axial-torsional fatigue experiments have been conducted at 760°C on uniform gage section, thin-walled tubular specimens of a wrought cobalt-base superalloy, Haynes 188. Test control and data acquisition were accomplished with a minicomputer. Fatigue lives of the in- and out-of-phase axial-torsional fatigue tests have been estimated with four different multiaxial fatigue life prediction models, a majority of which were developed primarily for predicting axial-torsional fatigue lives at room temperature. The models investigated were: (1) the von Mises equivalent strain range, (2) the modified multiaxiality factor approach, (3) the modified Smith-Watson-Topper parameter, and (4) the critical shear plane method of Fatemi, Socie, and Kurath. In general, life predictions by the von Mises equivalent strain range model were within a factor of 2 for a majority of the tests, and the predictions by the modified multiaxiality factor approach were within a factor of 2, while predictions of the modified Smith-Watson-Topper parameter and of the critical shear plane method of Fatemi, Socie, and Kurath were unconservative and conservative, respectively, by up to factors of 4. In some of the specimens tested under combined axial-torsional loading conditions, fatigue cracks initiated near extensometer indentations. Two design modifications have been proposed to the thin-walled tubular specimen to overcome this problem.

A critical plane‐strain energy density criterion for multiaxial low‐cycle fatigue life under non‐proportional loading

“…Figure 6 shows that Socie's model gives good predictions for proportional loading but unconservative predictions for non‐proportional loading. Kalluri and Bonacuse 18 applied the model for fatigue life prediction to Haynes 188 high‐alloy steel under non‐proportional loading. The results also showed that the predictions were unconservative by up to a factor of four, with the largest deviations occurring for the out‐of‐phase tests.…”

A method of fatigue life prediction in notched and un-notched components

“…6, for notched components, Neuber's analysis has been used to calculate the local stress/strain values at the notch root. The experimental fatigue lives of various materials extracted from the literature [13,[15][16][17][18][19] were plotted in Figs In a study by Fash [19], it was found that using the von Mises criterion, the experimentally predicted life data fall within a factor ranged 1.1-5.33 and with the Lohr-Ellison approach within a range factor of 1.1-7.0. Tipton and Nelson [20] reviewed a number of different methods and found that using the Brown and Miller model, the experimentalpredicted life data fall within a factor ranged 1.1-6.0 and the plastic work approach with a range factor of 1.1-5.0.…”

“…5. Specimen geometry: (a) 1045 steel[13], (b) Haynes 188[16], (c) 1020 HR steel[17], (d) high strength steel, t = 2.54 mm[15], (e) AA 2024-T3, t = 2.3 mm[18], (f) AA 7075-T6, t = 2.3 mm[18], (g) 4340 steel, t = 5.1 mm[18] and (h) 1045 steel[19].…”

A multi‐axial low‐cycle fatigue life prediction model considering effects of additional hardening

“…In order to verify the applicability of parameter n′, 5 kinds of materials, with n′ from 0.0195 to 0.4, were selected from the literature . In addition, to express the effects of additional hardening more intuitively, a strain parameter δε eq , as a temporary substitute for Γ t , is introduced where Δ ε' eq is equivalent strain calculated by Manson‐Coffin equation (Equation ) when experimental life N f is given.…”