Assessment of an Improved Multiaxial Strength Theory Based on Creep-Rupture Data for Type 316 Stainless Steel

1993 ◽  
Vol 115 (2) ◽  
pp. 177-184 ◽  
Author(s):  
R. L. Huddleston
Keyword(s):  
Stainless Steel ◽  
Stress Tensor ◽  
Rupture Life ◽  
Deviatoric Stress ◽  
Biaxial Stress ◽  
304 Stainless Steel ◽  
Strength Theory ◽  
Stress Rupture Life ◽  
316 Stainless Steel ◽  
Stress States

A new multiaxial strength theory incorporating three independent stress parameters was developed and reported by the author in 1984. It was formally incorporated into ASME Code Case N47-29 in 1990. In the earlier paper, the new model was shown to provide significantly more accurate stress-rupture life predictions than the classical theories of von Mises, Tresca, and Rankine, for type 304 stainless steel tested at 593°C under different biaxial stress states. Further assessments for other alloys are showing similar results. The current paper provides additional results for type 316 stainless steel specimens tested at 600°C under tension-tension and tension-compression stress states and shows 2–3 orders of magnitude reduction in the scatter in predicted versus observed lives. A key feature of the new theory, which incorporates the maximum deviatoric stress, the first invariant of the stress tensor, and the second invariant of the deviatoric stress tensor, is its ability to distinguish between life under tensile versus compressive stress states.

Fatigue Life Parameter for Type 304 Stainless Steel Under Biaxial-Tensile Loading at Elevated Temperature

1999 ◽  
Vol 121 (3) ◽  
pp. 305-312 ◽  
Author(s):  
Abdelkrim Zouani ◽  
Thang Bui-Quoc ◽  
Marie Bernard
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Stress Ratio ◽  
Biaxial Stress ◽  
304 Stainless Steel ◽  
Biaxial Tensile ◽  
The Mean ◽  
Stress States ◽  
Type 304 ◽  
Type 304 Stainless Steel

This paper describes a damage Parameter for predicting fatigue life under biaxial-tensile loadings. Several studies have focussed in the past on the situations where the in-plane biaxial stress ratio is negative; however, little attention has been paid for the cases involving both principal stresses in tension. A new testing method is used to carry out biaxial fatigue tests, at room and 427°C, on Type 304 stainless steel for different positive values of the stress ratio. In the experimental procedure, a disk-shaped specimen was used in connection with a spatial-arms mechanism which converts the uniaxial force generated by a conventional testing machine to radial forces extending the disk specimen. A modified virtual strain energy parameter is then suggested to normalize fatigue data obtained under a wide range of stress states. The proposed parameter accounts for the mean stress and the mean strain effects in an explicit form. In addition, the COD equivalent stress and strain concepts are adopted to account for the stress state biaxiality. The predictions of the proposed parameter are compared with the obtained experimental data and the correlation between the applied stress states and the experimental fatigue lives is discussed.

scholarly journals Breakdown and Evolution of the Protective Oxide Scales of AISI 304 and AISI 316 Stainless Steels under High-Temperature Oxidation

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
K. A. Habib ◽  
M. S. Damra ◽  
J. J. Saura ◽  
I. Cervera ◽  
J. Bellés
Keyword(s):  
Stainless Steel ◽  
Stainless Steels ◽  
Breakdown Point ◽  
304 Stainless Steel ◽  
Aisi 304 Stainless Steel ◽  
Protective Oxide ◽  
Aisi 304 ◽  
316 Stainless Steel ◽  
Aisi 316 Stainless Steel ◽  
Aisi 316

The failure of the protective oxide scales of AISI 304 and AISI 316 stainless steels has been studied and compared at 1,000°C in synthetic air. First, the isothermal thermogravimetric curves of both stainless steels were plotted to determine the time needed to reach the breakdown point. The different resistance of each stainless steel was interpreted on the basis of the nature of the crystalline phases formed, the morphology, and the surface structure as well as the cross-section structure of the oxidation products. The weight gain of AISI 304 stainless steel was about 8 times greater than that of AISI 316 stainless steel, and AISI 316 stainless steel reached the breakdown point about 40 times more slowly than AISI 304 stainless steel. In both stainless steels, reaching the breakdown point meant the loss of the protective oxide scale of Cr2O3, but whereas in AISI 304 stainless steel the Cr2O3scale totally disappeared and exclusively Fe2O3was formed, in AISI 316 stainless steel some Cr2O3persisted and Fe3O4was mainly formed, which means that AISI 316 stainless steel is more resistant to oxidation after the breakdown.

Evaluation of Creep Constitutive Equations for Type 304 Stainless Steel Under Repeated Multiaxial Loading

1982 ◽  
Vol 104 (3) ◽  
pp. 159-164 ◽  
Author(s):  
Y. Ohashi ◽  
N. Ohno ◽  
M. Kawai
Keyword(s):  
Stainless Steel ◽  
Strain Rate ◽  
Strain Hardening ◽  
Deviatoric Stress ◽  
304 Stainless Steel ◽  
Multiaxial Loading ◽  
Mixed Hardening ◽  
Principal Axes ◽  
Type 304 ◽  
Type 304 Stainless Steel

Four kinds of creep constitutive models, i.e., strain-hardening, modified strain-hardening, kinematic-hardening, and mixed-hardening theory, are evaluated on the basis of creep-test results on type 304 stainless steel at 650°C under repeated multiaxial loading. The predictions of the four models are compared with the experimental results. It is shown that substantial differences appear among these predictions under large rotations of the principal axes of the deviatoric stress tensor, and that none of them can describe with sufficient accuracy the transient increase of strain-rate and the noncollinearity between the deviatoric stress and creep strain-rate vectors which are observed just after the stress-rotations.

Creep and Creep Recovery of 304 Stainless Steel Under Combined Stress With a Representation by a Viscous-Viscoelastic Model

1980 ◽  
Vol 47 (4) ◽  
pp. 755-761 ◽  
Author(s):  
U. W. Cho ◽  
W. N. Findley
Keyword(s):  
Stainless Steel ◽  
Viscoelastic Model ◽  
Multiple Integral ◽  
Time Dependent ◽  
304 Stainless Steel ◽  
Creep Recovery ◽  
Strain Component ◽  
Stress Dependence ◽  
Nonlinear Stress ◽  
Stress States

Creep and creep-recovery data of 304 stainless steel are reported for experiments under constant combined tension and torsion at 593°C (1100°F). The data were represented by a viscous-viscoelastic model in which the strain was resolved into five components—elastic, plastic (time-independent), viscoelastic (time-dependent recoverable), and viscous (time-dependent nonrecoverable) which has separate positive and negative components. The data are well represented by a power function of time for each time-dependent strain. By applying superposition to the creep-recovery data, the recoverable creep strain was separated from the nonrecoverable. The form of stress-dependence associated with a third-order multiple integral representation was employed for each strain component. The time-dependent recoverable and nonrecoverable strains had different nonlinear stress dependence; but, the time-independent plastic strain and time-dependent nonrecoverable strain had similar stress-dependence. A limiting stress below which creep was very small or negligible was found for both recoverable and nonrecoverable components as well as a yield limit. The limit for recoverable creep was substantially less than the limits for nonrecoverable creep and yielding. The results showed that the model and equations used in the analysis described quite well the creep and creep-recovery under the stress states tested.

Effects of Prior Plasticity on Subsequent Creep of Type 316 Stainless Steel at Elevated Temperature

1986 ◽  
Vol 108 (1) ◽  
pp. 68-74 ◽  
Author(s):  
Y. Ohashi ◽  
M. Kawai ◽  
T. Momose
Keyword(s):  
Plastic Deformation ◽  
Stainless Steel ◽  
Creep Resistance ◽  
Tensile Direction ◽  
316 Stainless Steel ◽  
Plastic Prestraining ◽  
Axial Tensile ◽  
Thin Walled ◽  
Stress States ◽  
Tubular Specimens

Interaction between creep and plastic deformation was studied experimentally for type 316 stainless steel at 650°C, with special emphasis on creep behavior subsequent to plastic prestraining. In combined creep-plasticity experiments, thin-walled tubular specimens were first prestrained plastically in the axial tensile direction, and were subsequently subjected to constant stress creep under various multiaxial stress states with an identical effective stress. Furthermore, the variation in creep resistance due to the plastic prestrain was compared with that due to the same amount of creep prestrain. From the experimental results, it was found that creep resistance was markedly enhanced by the plastic prestrain and that the increase in the creep resistance depended on the amount and relative direction of the plastic prestrain. The creep resistance was increased more markedly by creep prestrain than the same amount of plastic strain.

Improvement of Stress-rupture Life for Modified-HR6W Austenitic Stainless Steel

2011 ◽  
Vol 27 (11) ◽  
pp. 1059-1064 ◽  
Author(s):  
Shiyun Cui ◽  
Zixing Zhang ◽  
Yulai Xu ◽  
Jun Li ◽  
Xueshan Xiao ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Rupture Life ◽  
Stress Rupture ◽  
Stress Rupture Life

Radiation-Induced Segregation in 316 and 304 Stainless Steels Irradiated at Low Dose Rate

2000 ◽  
Vol 650 ◽  
Author(s):  
T. R. Allen ◽  
J. I. Cole ◽  
J. Ohta ◽  
K. Dohi ◽  
H. Kusanagi ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Grain Boundary ◽  
Dose Rate ◽  
Stainless Steels ◽  
Low Dose ◽  
Bulk Composition ◽  
304 Stainless Steel ◽  
316 Stainless Steel ◽  
Low Dose Rate ◽  
Radiation Induced

ABSTRACTAs part of the shutdown of the EBR-II reactor, structural materials were retrieved to analyze the effects of long-term irradiation on mechanical properties and microstructure. In this work, the effect of low dose rate irradiation (10−7 to 10−8 dpa/s) on grain boundary composition in 316 and 304 stainless steels was analyzed. Samples were taken from surveillance specimens and subassemblies irradiated in the reflector region of EBR-II at temperatures from 371-390°C to maximum doses of 30 dpa. The effects of dose, dose rate, and bulk composition on radiation- induced segregation are analyzed. In 316 stainless steel, changes in grain boundary chromium and nickel concentrations occur faster than changes in iron and molybdenum concentrations. In 304 stainless steel, decreasing the dose rate increases the amount of grain boundary segregation. For a dose of 20 dpa, chromium depletion and nickel enrichment are greater in 304 stainless steel than in 316 stainless steel, the difference most likely due to dose rate. In both 304 and 316 stainless steels, the presence of a grain boundary precipitate significantly changes the composition of the adjacent grain boundary.

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