Fatigue and Cyclic Plasticity Properties of a Super-Austenitic Stainless Steel

Author(s):  
Sergiy Kalnaus ◽  
Feifei Fan ◽  
Yanyao Jiang

Tension-compression, torsion and axial-torsion experiments were conducted on AL-6XN® alloy. The main goal was to investigate experimentally, in detail, the cyclic plasticity behavior as well as fatigue life of AL-6XN® steel. Details of cyclic stress-strain response were collected during the experiments, which can serve as a baseline for development of cyclic plasticity model for this material. Microscopic observations of cracking behavior conducted in the present study allow connecting the fracture mechanism with fatigue life prediction. It was observed, that fatigue life of this material is a function of the fracture mode (mixed or tensile). The mixed cracking was observed in the specimens tested under higher applied strain levels, while the tensile cracking was revealed in the tests under lower strain amplitudes. Strain-life curves of the specimens failed in mixed mode and of those failed in tensile mode run parallel to each other, but the specimens that exhibit mixed failure mode show lower fatigue life as compared to the tensile mode specimens. Transition between mixed and tensile cracking orientations was studied in detail. The results of the experimental work presented in this study can serve for design of fatigue models for this material in the future.

2018 ◽  
Vol 2018 ◽  
pp. 1-16
Author(s):  
Weiying Meng ◽  
Liyang Xie ◽  
Yu Zhang ◽  
Yawen Wang ◽  
Xiaofang Sun ◽  
...  

This paper presents a study on the fatigue life prediction of notched fiber-reinforced 2060 Al-Li alloy laminates under spectrum loading by applying the constant life diagram. Firstly, a review on the state of the art of constant life diagram models for the life prediction of composite materials is given, which highlights the effect on the forecast accuracy. Then, the fatigue life of notched fiber-reinforced Al-Li alloy laminates (2/1 laminates and 3/2 laminates) is tested under cyclic stress, which has different stress cycle characteristics (constant amplitude loading and Mini-Twist spectrum loading). The introduced models are successfully realized based on the available experimental data of examined laminates. In the case of Mini-Twist spectrum loading, the effect of the constant life diagram on the life prediction accuracy of examined laminates is studied based on the rainflow-counting method and Miner damage criteria. The results show that the simple Goodman model and piecewise linear model have certain advantages compared to other complex models for the life prediction of notched fiber metal laminates with different structures under Mini-Twist loading. From the engineering perspective, the S-N curve prediction based on the piecewise linear model is most applicable and accurate among all the models.


2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Bipul Barua ◽  
Subhasish Mohanty ◽  
Joseph T. Listwan ◽  
Saurindranath Majumdar ◽  
Krishnamurti Natesan

In this paper, a cyclic-plasticity-based fully mechanistic fatigue modeling approach is presented. This is based on time-dependent stress–strain evolution of the material over the entire fatigue life rather than just based on the end of live information typically used for empirical S∼N curve-based fatigue evaluation approaches. Previously, we presented constant amplitude fatigue test based related material models for 316 stainless steel (SS) base, 508 low alloy steel base, and 316 SS-316 SS weld which are used in nuclear reactor components such as pressure vessels, nozzles, and surge line pipes. However, we found that constant amplitude fatigue data-based models have limitation in capturing the stress–strain evolution under arbitrary fatigue loading. To address the aforementioned limitation, in this paper, we present a more advanced approach that can be used for modeling the cyclic stress–strain evolution and fatigue life not only under constant amplitude but also under any arbitrary (random/variable) fatigue loading. The related material model and analytical model results are presented for 316 SS base metal. Two methodologies (either based on time/cycle or based on accumulated plastic strain energy (APSE)) to track the material parameters at a given time/cycle are discussed and associated analytical model results are presented. From the material model and analytical cyclic plasticity model results, it is found that the proposed cyclic plasticity model can predict all the important stages of material behavior during the entire fatigue life of the specimens with more than 90% accuracy.


2010 ◽  
Vol 643 ◽  
pp. 91-97
Author(s):  
Fabio José Carvalho França ◽  
Nilmário Galdino Guedes ◽  
Severino Jackson Guedes de Lima ◽  
Tadeu Antônio de Avezedo Melo ◽  
Rodinei Medeiros Gomes

The effect of cyclic deformation on the stability of superelasticity was investigated for the Cu-12wt%Al-0.5wy%Be alloy. The loading and unloading cyclic tensile tests were performed at room temperature and at 57oC with the maximum constant strain of 4%. The effect of holding the applied strain for a period of time on the superelastic properties was also investigated. It was confirmed that the total volume fraction of the retained martensite changes with time after unloading cycle, leading to the reduction of the residual strain. Additionally, the residual strain increases as the loading cycle of the applied strain is kept constant for a period of time.


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