scholarly journals Fatigue Life Properties of Stainless Steels in Wide Ranged Biaxial Stress States using a Hollow Cylinder Specimen

2019 ◽  
Vol 300 ◽  
pp. 09004
Author(s):  
Shunsuke Saito ◽  
Fumio Ogawa ◽  
Takamoto Itoh
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Hollow Cylinder ◽  
Stainless Steels ◽  
Equivalent Stress ◽  
Testing Machine ◽  
Biaxial Stress ◽  
Loading Path ◽  
Stress Range ◽  
Inner Pressure

Stress controlled multiaxial fatigue tests were carried out using hollow cylinder specimens of type 430 and 316 stainless steels at room temperature. A newly developed fatigue testing machine which can apply push-pull loading and inner pressure to the specimen was used. For inner pressure, oil was put inside of the specimen. 7 types of cyclic loading paths were employed by combining axial and hoop stresses; a Pull, an Inner-pressure, a Push-pull, an Equi-biaxial, a Square-shape, a LT-shape and a LC-shape. Fatigue lives vary depending on the loading path when those were evaluated by the maximum Mises’ equivalent stress range on inner surface of the specimen. The fatigue lives of both the steels showed a similar tendency. However, the following difference was identified. Specifically, differences in fatigue lives of type 430 stainless steel between the uniaxial loading and the multiaxial tests were large, while those of type 316 stainless steel were small. To discuss difference in fatigue life properties between both steels, this study investigates the effect of the shear stress range, mean stress and additional hardening and which leads to evaluate the lives suitably.

Fatigue Life Properties of Stainless Steels in Wide Ranged Biaxial Stress State

2019 ◽  
Vol 795 ◽  
pp. 60-65
Author(s):  
Shunsuke Saito ◽  
Fumio Ogawa ◽  
Takamoto Itoh
Keyword(s):  
Fatigue Life ◽  
Stress State ◽  
Stainless Steels ◽  
Equivalent Stress ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Biaxial Stress ◽  
Loading Path ◽  
Inner Pressure ◽  
Biaxial Stress State

Multiaxial fatigue tests consisting of push-pull loading and cyclic inner pressure were carried out using hollow cylinder specimens of type 430 stainless and type 316 stainless steels at room temperature. 7 types of cyclic loading paths were employed by combining axial and hoop stresses: a Pull, an Inner-pressure, a Push-pull, an Equi-biaxial, a Square-shape, a LT-shape and a LC-shape. Fatigue lives vary depending on the loading path when those were evaluated by the maximum Mises’ equivalent stress on inner surface of the specimen. The fatigue lives of both the steels showed a similar tendency although some Pull tests take longer fatigue life when cracks initiated from inside surface of the specimen. This study investigated the crack initiation and propagation behaviors as well as the initiation of oil leakage to prove the behavior and discusses life evaluation for two steels under wide ranged biaxial stress state, too.

The Biaxial Stress-Strain Curves of Sheet Metals

2010 ◽  
Vol 44-47 ◽  
pp. 2519-2523
Author(s):  
Hai Bo Wang ◽  
Min Wan ◽  
Yu Yan ◽  
Xiang Dong Wu
Keyword(s):  
Transverse Direction ◽  
Biaxial Loading ◽  
Testing Machine ◽  
Rolling Direction ◽  
Biaxial Stress ◽  
Loading Path ◽  
Sheet Metals ◽  
Stress Strain ◽  
Loading Paths ◽  
Loading Ratio

Biaxial tensile tests of 5754O aluminum alloy sheet and B170P1 steel sheet were performed under linear loading paths with cruciform specimens and a biaxial loading testing machine. The stress-strain curves under different loading paths were obtained. It is found that the loading path has a significant influence on the stress-strain curves, i.e., the stress-strain curves vary with the loading path. The stress-strain curves in the rolling direction become higher with the decrease of the loading ratio (the ratio of the load along the rolling direction to that along the transverse direction) from 4:0 to 4:4. Meanwhile the stress-strain curves in the transverse direction become lower with the decrease of the loading ratio from 4:4 to 0:4. Based on Yld2000-2d yield criterion, the experimental phenomena of the two kinds of sheet metals under biaxial tension were explained theoretically.

Practical Criterion for Estimation of Notch Fatigue Strength

2004 ◽  
Author(s):  
Hiroshi Matsuno ◽  
Yoshihiko Mukai
Keyword(s):  
Surface Layer ◽  
Fatigue Strength ◽  
Stress Ratio ◽  
Notch Root ◽  
Equivalent Stress ◽  
Cyclic Stress ◽  
Biaxial Stress ◽  
Combined Loading ◽  
Stress Range ◽  
Stress Cycling

In the present study, a practical criterion for the estimation of the fatigue strength of notched specimens is discussed from a practical standpoint of design and maintenance of machines and structures. First of all, a hypothesis of “Fatigue Plastic Adaption” is proposed as one idea that is available to combine microscopic and macroscopic approaches to fatigue plasticity. The hypothesis expresses that, at a surface layer and at a notch root, elastic deformation arising at the cyclic maximum stress is transformed into local and inhomogeneous plastic deformation. Based on the hypothesis, mechanical models are constructed in order to simulate cyclic stress behavior at the surface layer and at the notch root. As a result, “Equivalent Stress Ratio” is formulated as a parameter for correspondence of cyclic stress conditions between notched and unnotched specimens. Moreover, on the basis of the hypothesis of the plastic adaptation, the equation of the equivalent stress ratio is also derived for the case of biaxial stress cycling in torsion, and it is finally expanded for the general case of proportional multiaxial stress cycling. The published fatigue data concerning tension-compression, bending, torsion and their combined loading are rearranged on the diagram where an abscissa indicates the equivalent stress ratio and an ordinate indicates the stress range at the notch root. As the result, it is recognized that the relation between the equivalent stress ratio and the notch-root-concentrated stress range is shown by a certain curve proper to material in spite of difference of stress concentration factors, loading types and mean stresses. Consequently, a criterion for notch fatigue strength is described on the basis of the equivalent stress ratio, i.e., the notch-root-concentrated stress range at the fatigue strength of the notched specimen for any nominal stress ratio is identical with the fatigue strength of the unnotched specimen for the equivalent stress ratio.

Evaluation of Fatigue Damage in LWR Water With and Without Threshold and Moderation Factor

2003 ◽  
Author(s):  
Makoto Higuchi ◽  
Kazuya Tsutsumi ◽  
Katsumi Sakaguchi
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Stainless Steels ◽  
Power Plants ◽  
Light Water Reactor ◽  
Low Alloy Steels ◽  
Light Water ◽  
Water Reactor ◽  
Fatigue Data ◽  
Fatigue Life Reduction

During the past twenty years, the fatigue initiation life of LWR structural materials, carbon, low alloy and stainless steels has been shown to decrease remarkably in the simulated LWR (light water reactor) coolant environments. Several models for evaluating the effects of environment on fatigue life reduction have been developed based on published environmental fatigue data. Initially, based on Japanese fatigue data, Higuchi and Iida proposed a model for evaluating such effects quantitatively for carbon and low alloy steels in 1991. Thereafter, Chopra et al. proposed other models for carbon, low alloy and stainless steels by adding American fatigue data in 1993. Mehta developed a new model which features the threshold concept and moderation factor in Chopra’s model in 1995. All these models have undergone various revisions. In Japan, the MITI (Ministry of International Trade and Industry) guideline on environmental fatigue life reduction for carbon, low alloy and stainless steels was issued in September 2000, for evaluating of aged light water reactor power plants. The MITI guideline provide equations for calculations applicable only to stainless steel in PWR water and consequently Higuchi et al. proposed in 2002 a revised model for stainless steel which incorporates new equations for evaluation of environmental fatigue reduction in BWR water. The paper compares the latest versions of these models and discusses the conservativeness of the models by comparison of the models with available test data.

High-strain fatigue of stainless-steel cylinders: Experimental results and their application to pressure-vessel design

1967 ◽  
Vol 2 (4) ◽  
pp. 290-297 ◽  
Author(s):  
C Ruiz
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Static Pressure ◽  
Elastic Stress ◽  
High Strain ◽  
Pressure Vessels ◽  
Supplementary Information ◽  
Test Results ◽  
Stress Range ◽  
Fatigue Design

Thin cylindrical specimens, plain and with deep axial grooves, have been tested under pulsating pressure and under static pressure with cyclic axial straining. The test results, together with some supplementary information from other authors, show that Langer's method, based on an elastic-stress analysis, is applicable to the fatigue design of pressure vessels. Design curves for the establishment of the acceptable elastic-stress range corresponding to a given fatigue life are proposed. Attention is drawn to the limitations of Langer's method.

Notch Effect in Biaxial Low Cycle Fatigue at Elevated Temperatures

1989 ◽  
Vol 111 (3) ◽  
pp. 286-293 ◽  
Author(s):  
H. Umeda ◽  
M. Sakane ◽  
M. Ohnami
Keyword(s):  
Fatigue Life ◽  
Elevated Temperatures ◽  
Low Cycle Fatigue ◽  
Notch Root ◽  
Equivalent Stress ◽  
Potential Drop ◽  
Biaxial Stress ◽  
Prediction Methods ◽  
Notch Effect ◽  
Cycle Fatigue

This paper describes the notch effect in biaxial low cycle fatigue of an austenitic stainless steel SUS 304 at 873K in air. Mises’ equivalent stress controlled fatigue tests were carried out for the three kinds of round notched specimens in push-pull/torsion biaxial stress states. Cracks emanated at the notch root were measured by a d.c. potential drop method. Reduction in the fatigue life due to the notch was most significant in the reversed torsion test in comparison with the push-pull and combined push-pull/reversed torsion tests. The conventional fatigue life prediction methods, i.e., the Neuber’s rule, the Stowell’s method, and the Koe’s method, were applied to the experimental data and the accuracy of the prediction methods were discussed.

Fatigue With Hold Times Simulating NPP Normal Operation Results for Stainless Steel Grades 304L and 347

2017 ◽  
Author(s):  
H. Ertugrul Karabaki ◽  
Jussi Solin ◽  
Marius Twite ◽  
Matthias Herbst ◽  
Jonathan Mann ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Steady State ◽  
Fatigue Life ◽  
Stainless Steels ◽  
Fatigue Behavior ◽  
Material Behavior ◽  
Cyclic Behavior ◽  
Normal Operation ◽  
Major Power ◽  
Steel Grades

The cyclic behavior and endurance of austenitic stainless steels tested under NPP-relevant laboratory conditions has been studied. It had been earlier shown that long intervals between fatigue transients can affect the fatigue performance in stainless steels that are generally used in NPP primary piping. If this can be confirmed, then the transferability between laboratory results, design curves and the fatigue behavior of NPP components during plant operation shall be addressed. In addition to coolant water environmental effects, the material response during steady state normal operation should also be accounted for. Advanced Fatigue Methodologies (AdFaM), a joint project of European research laboratories, vendors and plant operators was focused on empirical and mechanistic investigations to confirm the claimed effects of hold times on fatigue life. Strain-controlled fatigue tests incorporating accelerated hold times at temperatures between 290°C and 420°C were performed on stabilized and non-stabilized stainless steel grades, which are used in Germany and the UK. Two material batches of both alloy types (304L and 347) were studied. The mechanisms responsible for the observed variations in stress response and fatigue life have been investigated using a range of microscopy techniques. The results confirmed the extension of fatigue life due to hold times in both stabilized and non-stabilized grades. This life extension appears to be linked to hold hardening observed in the cyclic behavior of both alloys. Tests incorporating hold times may be more representative of material behavior in NPPs, where temperature transients due to start-ups, shutdowns and major power changes may be separated by long periods of steady state operation. This gives reason to consider the transferability of standard laboratory test data to fatigue assessments of NPP components, and to propose a new factor ( Fhold ) as part of an advanced fatigue methodology and realistic transferability factor: Freal = Fen × Fhold.

A New Nonproportional Low Cycle Fatigue Life Prediction Method for Type 304 Stainless Steel

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
Bowen Liu ◽  
Xiangqiao Yan
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Prediction Method ◽  
Fatigue Life Prediction ◽  
New Method ◽  
304 Stainless Steel ◽  
Loading Path ◽  
Prediction Approach

A new method is put forward to predict fatigue life for low cycle nonproportional loading based on the Itoh criterion. The proposed method considers the multi-axiality influence on the reference maximum principal strain path and the calculation of nonproportionality factor Fnp by utilizing a multi-axial fatigue life prediction approach based on the modified Wöhler curve method. Different from the hypothesis of previous integral models for computing factor Fnp where the loading path is considered uniform, a new model using an inhomogeneous integral is presented and a path-dependent weight factor is defined to describe this inhomogeneity. The experimental tests of Itoh on 304 stainless steel with 14 different loading cases are referenced to examine the validity of the new method.

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