An Experimental Study on the Effect of Prior Plastic Straining on Creep Behavior of 304 Stainless Steel

1993 ◽  
Vol 115 (2) ◽  
pp. 200-203 ◽  
Author(s):  
Z. Xia ◽  
F. Ellyin
Keyword(s):  
Stainless Steel ◽  
Plastic Strain ◽  
Strain Rate ◽  
Creep Behavior ◽  
Test Procedure ◽  
Constant Strain Rate ◽  
304 Stainless Steel ◽  
Creep Model ◽  
Plastic Strain Rate ◽  
Creep Tests

Constant strain-rate plastic straining followed by creep tests were conducted to investigate the effect of prior plastic straining on the subsequent creep behavior of 304 stainless steel at room temperature. The effects of plastic strain and plastic strain-rate were delineated by a specially designed test procedure, and it is found that both factors have a strong influence on the subsequent creep deformation. A creep model combining the two factors is then developed. The predictions of the model are in good agreement with the test results.

An Investigation of Transient Creep by Means of Endochronic Viscoplasticity and Experiment

1995 ◽  
Vol 117 (3) ◽  
pp. 260-268 ◽  
Author(s):  
Han C. Wu ◽  
Chin C. Ho
Keyword(s):  
Stainless Steel ◽  
Strain Rate ◽  
Creep Strain ◽  
Constant Strain Rate ◽  
Transient Creep ◽  
Constant Stress ◽  
Stress Rate ◽  
304 Stainless Steel ◽  
Unified Approach ◽  
Creep Tests

Creep of metals has been investigated by means of the endochronic constitutive equation. This is a unified approach. Transient creep tests have been conducted on 304 stainless-steel specimens with carefully monitored precreep loading stage, either loaded at a prescribed constant strain-rate or at a constant stress-rate. It has been found that, for the same hold stress, the creep strain is larger for test with a constant stress-rate preloading than that for a constant strain-rate preloading. This is an effect of plasticity-creep interaction. In all cases, the initial creep strain rate is a continuation of the preloading strain rate. The theory satisfactorily describes the experimental results.

A Study of Fatigue (Cyclic Deformation) Behavior in FCC Metals Using Strain Rate Change Tests

2008 ◽  
Vol 378-379 ◽  
pp. 371-384 ◽  
Author(s):  
George C. Kaschner ◽  
Jeffrey C. Gibeling
Keyword(s):  
Stainless Steel ◽  
Plastic Strain ◽  
Strain Rate ◽  
Cyclic Deformation ◽  
Low Cycle Fatigue ◽  
Pure Copper ◽  
Dislocation Motion ◽  
304 Stainless Steel ◽  
Plastic Strain Rate ◽  
Activation Area

Strain rate jump tests were performed during low cycle fatigue using plastic strain rate as the real time computed control variable. Test materials included OFE polycrystalline copper, AA7075-T6 aluminum, and 304 stainless steel. The evolution of dislocation interactions was observed by evaluating the activation area and true stress as a function of cumulative plastic strain. Activation area values for each of the three materials were evaluated from an initial state to saturation. All three materials exhibit a deviation from Cottrell-Stokes law during cyclic deformation. Tests performed on each of the three materials at saturation reveal a dependence of activation area on plastic strain amplitude for copper and aluminum but no such relationship for stainless steel. These results reflect a contrast between wavy slip for pure copper and 7075 aluminum versus planar slip for 304 stainless steel tested at room temperature. Dislocation motion in copper transitions from forest dislocation cutting [1-6] to increasing contributions of cross slip. Dislocation motion in 7075 aluminum and 304 stainless steel is controlled by obstacles that are characteristically more thermal than forest dislocations: obstacles in 7075-T6 aluminum are identified as solutes from re-dissolved particles; obstacles in 304 stainless steel are also solutes.

An Assessment of the Method Used to Determine Activation Parameters in L12 Alloys

1998 ◽  
Vol 552 ◽  
Author(s):  
B. Matterstock ◽  
G. Saada ◽  
J. Bonneville ◽  
J. L Martin
Keyword(s):  
Mechanical Properties ◽  
Theoretical Analysis ◽  
Plastic Strain ◽  
Strain Rate ◽  
Characteristic Time ◽  
Constant Strain Rate ◽  
Activation Parameters ◽  
Plastic Strain Rate ◽  
Clear Indication ◽  
Load Relaxation

ABSTRACTThe characterisation of dislocation mechanisms in connection with macroscopic mechanical properties are usually performed through transient tests, such as strain-rate jumps, load relaxations or creep experiments. The present paper includes a careful and complete theoretical analysis of the relaxation and the creep kinetics. We experimentally show that the plastic strain-rate is continuous at the transition between constant strain-rate conditions and both load relaxation and creep test. The product of the plastic strain-rate at the onset of the transient test () with the characteristic time (tk) of the transient is found to be independent of , as theoretically expected. This is a clear indication that the assumptions underlying the theoretical analysis are relevant.

Experimental Evaluation of Creep Constitutive Equations for Type 304 Stainless Steel Under Non-Steady Multiaxial States of Stress

1986 ◽  
Vol 108 (2) ◽  
pp. 119-126 ◽  
Author(s):  
S. Murakami ◽  
N. Ohno ◽  
H. Tagami
Keyword(s):  
Stainless Steel ◽  
Creep Behavior ◽  
Stress Change ◽  
304 Stainless Steel ◽  
Test Time ◽  
Surface Model ◽  
Creep Tests ◽  
Type 304 ◽  
Type 304 Stainless Steel ◽  
Multiaxial Loadings

In order to evaluate the validity and limitations of the creep-hardening surface model proposed by the present authors, a series of creep tests for type 304 stainless steel were performed at 600°C under various non-steady multiaxial loadings. The test time and the interval of stress change were 960 hr and 48 or 96 hr, respectively, and five kinds of stress histories consisting of randomly varying stress magnitude, stress direction and interval of stress change were employed. It was found that the creep-hardening surface model describes sufficiently well the creep behavior observed in this work.

An Experimental Study of the Structure of Constitutive Equations for Nonproportional Cyclic Plasticity

1985 ◽  
Vol 107 (4) ◽  
pp. 307-315 ◽  
Author(s):  
D. L. McDowell
Keyword(s):  
Plastic Strain ◽  
Strain Rate ◽  
Yield Surface ◽  
Hysteresis Loops ◽  
Cyclic Plasticity ◽  
304 Stainless Steel ◽  
Plastic Strain Rate ◽  
Hardening Modulus ◽  
Rate Vector ◽  
Strain Rate Vector

Three type 304 stainless steel specimens of the same geometry were subjected to complex, cyclic axial-torsional histories characterized by varying degrees of non-proportionality of straining. All tests were at room-temperature. The data from cyclically stable hysteresis loops were reduced and the direction of the plastic strain rate vector, variation of plastic hardening modulus, and direction of translation of a rate and time-independent yield surface were studied. It is shown that the independent variables in a Mroz-type formulation map the experimental results with a higher degree of uniqueness than other popular formulations studied for both the hardening modulus and direction of yield surface translation. Also, the plastic strain rate is not, in general, in the direction of the deviatoric stress or stress rate.

Transient Creep Behavior of γ-TiAl Polycrystals

1996 ◽  
Vol 460 ◽  
Author(s):  
B. Viguier ◽  
J. Bonneville ◽  
P. Spätig ◽  
J. L. Martin
Keyword(s):  
Plastic Strain ◽  
Strain Rate ◽  
Strain Hardening ◽  
Creep Behavior ◽  
Room Temperature ◽  
Constant Strain Rate ◽  
Transient Creep ◽  
Load Relaxation ◽  
Hardening Coefficient ◽  
Good Agreement

ABSTRACTTwo types of transient creep experiments performed along stress-strain curves are described and successfully applied to γ TiAl polycrystals at room temperature. They allow to determine activation volumes in good agreement with those measured through successive load relaxation tests. In addition, the combination of the latter method and the present ones provides relevant values of the plastic strain hardening coefficient. This latter parameter is found to exhibit similar values in transient as well as during constant strain rate tests.

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.

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