Low Cycle Fatigue Behavior of a Near-α Ti Alloy Containing Rare Earth Nd

Low cyclic behavior of a new type near-α titanium alloy containing rare earth Nd (Ti60) with and without dwell time introduced at maximum tensile strain has been investigated at ambient temperature and 600°C. The results show that, Ti60 alloy exhibits a cyclic softening behavior at almost all strain levels being investigated. The cyclic processes show good agreement with predictions based on the fatigue crack propagation model. At 600°C, the LCF life of Nd-bearing near-α titanium alloy is superior to that at room temperature within the investigated strain range, which indicates that Ti60 alloy is a good candidate for high temperature component under complicated load and temperature conditions. The results also show that the creep-fatigue interaction is related to the strain range applied. The creep-fatigue fracture is characterized by transgranular fracture mode due to the formation of matrix voids induced by Nd-bearing particles.

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High-Temperature Low-Cycle Fatigue Behavior of MarBN at 600 °C

Journal of Pressure Vessel Technology ◽

10.1115/1.4031724 ◽

2016 ◽

Vol 138 (4) ◽

Cited By ~ 8

Author(s):

Richard A. Barrett ◽

Eimear M. O'Hara ◽

Padraic E. O'Donoghue ◽

Sean B. Leen

Keyword(s):

High Temperature ◽

Low Cycle Fatigue ◽

Kinematic Hardening ◽

Fatigue Behavior ◽

Strain Range ◽

Material Model ◽

Cyclic Softening ◽

Cyclic Strength ◽

Cycle Fatigue ◽

Viscoplastic Material

This paper presents the high-temperature low-cycle fatigue (HTLCF) behavior of a precipitate strengthened 9Cr martensitic steel, MarBN, designed to provide enhanced creep strength and precipitate stability at high temperature. The strain-controlled test program addresses the cyclic effects of strain-rate and strain-range at 600 °C, as well as tensile stress-relaxation response. A recently developed unified cyclic viscoplastic material model is implemented to characterize the complex cyclic and relaxation plasticity response, including cyclic softening and kinematic hardening effects. The measured response is compared to that of P91 steel, a current power plant material, and shows enhanced cyclic strength relative to P91.

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Effects of Thermal Exposure on Low Cycle Fatigue Behavior of Ti600 Titanium Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.118-120.611 ◽

2010 ◽

Vol 118-120 ◽

pp. 611-615

Author(s):

Teng Yu ◽

Lei Wang ◽

Yong Qing Zhao ◽

Yang Liu

Keyword(s):

Titanium Alloy ◽

Strain Amplitude ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Thermal Exposure ◽

Cyclic Softening ◽

Total Strain ◽

Total Strain Amplitude ◽

Cycle Fatigue ◽

Α2 Phase

Effects of thermal exposure on low cycle fatigue behavior of Ti600 alloy were investigated by LSCM, SEM and TEM. The results demonstrated that both the NTE specimens and the TE specimens showed the cyclic softening, within a total strain amplitude range from ±0.45% to ±1.00%. Since the α2 phase precipitated in the αp phase during thermal exposure, the resistance of fatigue crack propagation of αp phase could be increased by the precipitation of α2 phase. Therefore, the low cycle fatigue (LCF) lives of Ti600 alloy after thermal exposure were longer than those without thermal exposure, at the same total strain amplitude.

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Thermomechanical Fatigue Behavior of the Ferritic Stainless Steel

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.297-300.1146 ◽

2005 ◽

Vol 297-300 ◽

pp. 1146-1151 ◽

Cited By ~ 3

Author(s):

Keum Oh Lee ◽

Seong Gu Hong ◽

Sam Son Yoon ◽

Soon Bok Lee

Keyword(s):

Stainless Steel ◽

Ferritic Stainless Steel ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Strain Range ◽

Thermomechanical Fatigue ◽

Propagation Model ◽

Plastic Strain Range ◽

Proposed Model ◽

Life Prediction Model

A thermomechanical fatigue (TMF) life prediction model for ferritic stainless steel, used in exhaust manifold of automobile, was developed based on Tomkins’ two-dimensional crack propagation model. Low-cycle fatigue (LCF) and TMF tests were carried out in a wide temperature range from 200 to 650°C. New concept of plastic strain range on TMF was proposed. Effective stress concept was introduced to get a reasonable stress range in TMF hysteresis loop. The proposed model predicted TMF life within 2X scatter band. The experimental results reveal that TMF life is about 10% of isothermal fatigue life.

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Influence of turning tool wear on the surface integrity and anti-fatigue behavior of Ti1023

Advances in Mechanical Engineering ◽

10.1177/16878140211011278 ◽

2021 ◽

Vol 13 (4) ◽

pp. 168781402110112

Author(s):

Li Xun ◽

Wang Ziming ◽

Yang Shenliang ◽

Guo Zhiyuan ◽

Zhou Yongxin ◽

...

Keyword(s):

Surface Roughness ◽

Plastic Deformation ◽

Titanium Alloy ◽

Fatigue Life ◽

Tool Wear ◽

Surface Integrity ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Machined Surface ◽

Deformation Layer

Titanium alloy Ti1023 is a typical difficult-to-cut material. Tool wear is easy to occur in machining Ti1023, which has a significant negative effect on surface integrity. Turning is one of the common methods to machine Ti1023 parts and machined surface integrity has a direct influence on the fatigue life of parts. To control surface integrity and improve anti-fatigue behavior of Ti1023 parts, it has an important significance to study the influence of tool wear on the surface integrity and fatigue life of Ti1023 in turning. Therefore, the effect of tool wear on the surface roughness, microhardness, residual stress, and plastic deformation layer of Ti1023 workpieces by turning and low-cycle fatigue tests were studied. Meanwhile, the influence mechanism of surface integrity on anti-fatigue behavior also was analyzed. The experimental results show that the change of surface roughness caused by worn tools has the most influence on anti-fatigue behavior when the tool wear VB is from 0.05 to 0.25 mm. On the other hand, the plastic deformation layer on the machined surface could properly improve the anti-fatigue behavior of specimens that were proved in the experiments. However, the higher surface roughness and significant surface defects on surface machined utilizing the worn tool with VB = 0.30 mm, which leads the anti-fatigue behavior of specimens to decrease sharply. Therefore, to ensure the anti-fatigue behavior of parts, the value of turning tool wear VB must be rigorously controlled under 0.30 mm during finishing machining of titanium alloy Ti1023.

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Component Low Cycle Fatigue Behavior Based on Standard Calculation Procedure and Non-Linear FEA

Volume 3B: Design and Analysis ◽

10.1115/pvp2017-66071 ◽

2017 ◽

Author(s):

Jürgen Rudolph ◽

Adrian Willuweit ◽

Steffen Bergholz ◽

Christian Philippek ◽

Jevgenij Kobzarev

Keyword(s):

Power Plants ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Hybrid Approach ◽

Combined Cycle ◽

Cycle Fatigue ◽

Element Analysis ◽

Constitutive Material Model ◽

Standard Design ◽

Creep Fatigue

Components of conventional power plants are subject to potential damage mechanisms such as creep, fatigue and their combination. These mechanisms have to be considered in the mechanical design process. Against this general background — as an example — the paper focusses on the low cycle fatigue behavior of a main steam shut off valve. The first design check based on standard design rules and linear Finite Element Analysis (FEA) identifies fatigue sensitive locations and potentially high fatigue usage. This will often occur in the context of flexible operational modes of combined cycle power plants which are a characteristic of the current demands of energy supply. In such a case a margin analysis constitutes a logical second step. It may comprise the identification of a more realistic description of the real operational loads and load-time histories and a refinement of the (creep-) fatigue assessment methods. This constitutes the basis of an advanced component design and assessment. In this work, nonlinear FEA is applied based on a nonlinear kinematic constitutive material model, in order to simulate the thermo-mechanical behavior of the high-Cr steel component mentioned above. The required material parameters are identified based on data of the accessible reference literature and data from an own test series. The accompanying testing campaign was successfully concluded by a series of uniaxial thermo-mechanical fatigue (TMF) tests simulating the most critical load case of the component. This detailed and hybrid approach proved to be appropriate for ensuring the required lifetime period of the component.

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A Direct Method on the Evaluation of Cyclic Steady State of Structures With Creep Effect

Journal of Pressure Vessel Technology ◽

10.1115/1.4028164 ◽

2014 ◽

Vol 136 (6) ◽

Cited By ~ 14

Author(s):

Haofeng Chen ◽

Weihang Chen ◽

James Ure

Keyword(s):

Fatigue Damage ◽

Mechanical Load ◽

Direct Method ◽

Load Condition ◽

Hysteresis Loops ◽

Strain Range ◽

Cyclic Behavior ◽

Direct Evaluation ◽

Plastic Strain Range ◽

Creep Fatigue

This paper describes a new extension of the linear matching method (LMM) for the direct evaluation of cyclic behavior with creep effects of structures subjected to a general load condition in the steady cyclic state, with the new implementation of the cyclic hardening model and time hardening creep constitutive model. A benchmark example of a Bree cylinder and a more complicated three-dimensional (3D) plate with a center hole subjected to cyclic thermal load and constant mechanical load are analyzed to verify the applicability of the new LMM to deal with the creep fatigue damage. For both examples, the stabilized cyclic responses for different loading conditions and dwell time periods are obtained and validated. The effects of creep behavior on the cyclic responses are investigated. The new LMM procedure provides a general purpose technique, which is able to generate both the closed and nonclosed hysteresis loops depending upon the applied load condition, providing details of creep strain and plastic strain range for creep and fatigue damage assessments with creep fatigue interaction.

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Cyclic Softening Effect on Design Margin of JLF-1 Steel

Volume 1: Plant Operations, Maintenance, Engineering, Modifications, Life Cycle and Balance of Plant; Nuclear Fuel and Materials; Radiation Protection and Nuclear Technology Applications ◽

10.1115/icone21-16545 ◽

2013 ◽

Author(s):

Huailin Li

Keyword(s):

Elevated Temperature ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Cyclic Softening ◽

Fatigue Properties ◽

Cycle Fatigue ◽

Softening Effect ◽

As Stress ◽

Supercritical Water Cooled Reactor ◽

Design Margin

A reduced-activation ferritic/martensitic (RAF/M) steel, JLF-1, is considered as one of the candidate structure material of the fusion reactors and supercritical water-cooled reactor (SCWR). Low cycle fatigue properties of JLF-1 steel at elevated temperature are the design base to provide adequate design margin against postulated mechanism that could experience during its design life, such as stress range, plastic deformation, and cyclic softening etc. However, the reduction in design margin is significant when the cyclic softening happens in cyclic deformation at RT, 673K, 873K. Thus, for the application as the structural materials, it is necessary to evaluate low cycle fatigue behavior and cyclic softening of JLF-1 steel at elevated temperature since those properties of material at elevated temperature are the key issue for design.

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The Effect of Nitrogen Alloying on the Low Cycle Fatigue and Creep-Fatigue Interaction Behavior of 316LN Stainless Steel

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.794.441 ◽

2013 ◽

Vol 794 ◽

pp. 441-448 ◽

Cited By ~ 4

Author(s):

G.V. Prasad Reddy ◽

R. Sandhya ◽

M.D. Mathew ◽

S. Sankaran

Keyword(s):

Stainless Steel ◽

Strain Rate ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Hold Time ◽

Cyclic Plasticity ◽

Dynamic Strain ◽

Cycle Fatigue ◽

Intergranular Cracking ◽

Creep Fatigue

Low cycle fatigue (LCF) and Creep-fatigue interaction (CFI) behavior of 316LN austenitic stainless steel alloyed with 0.07, 0.11, 0.14, .22 wt.% nitrogen is briefly discussed in this paper. The strain-life fatigue behavior of these steels is found to be dictated by not only cyclic plasticity but also by dynamic strain aging (DSA) and secondary cyclic hardening (SCH). The influence of the above phenomenon on cyclic stress response and fatigue life is evaluated in the present study. The above mentioned steels exhibited both single-and dual-slope strain-life fatigue behavior depending on the test temperatures. Concomitant dislocation substructural evolution has revealed transition in substructures from planar to cell structures justifying the change in slope. The beneficial effect of nitrogen on LCF life is observed to be maximum for 316LN with nitrogen in the range 0.11 - 0.14 wt.%, for the tests conducted over a range of temperatures (773-873 K) and at ±0.4 and 0.6 % strain amplitudes at a strain rate of 3*10-3 s-1. A decrease in the applied strain rate from 3*10-3 s-1 to 3*10-5 s-1 or increase in the test temperature from 773 to 873 K led to a peak in the LCF life at a nitrogen content of 0.07 wt.%. Similar results are obtained in CFI tests conducted with tensile hold periods of 13 and 30 minutes. Fractography studies of low strain rate and hold time tested specimens revealed extensive intergranular cracking.

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Multiaxial Low Cycle Fatigue Life Prediction at 300 °C Using Equivalent Strain Appoach

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.361-363.1669 ◽

2011 ◽

Vol 361-363 ◽

pp. 1669-1672

Author(s):

Wen Xiao Zhang ◽

Guo Dong Gao ◽

Guang Yu Mu

Keyword(s):

Fatigue Life ◽

Life Prediction ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Strain Range ◽

Cyclic Fatigue ◽

Equivalent Strain ◽

Multiaxial Fatigue ◽

Fatigue Life Prediction ◽

Cycle Fatigue

The low cycle fatigue behavior was experimentally studied with the 3-dimension notched LD8 aluminum alloy specimens at 300°C. The 3- dimension stress-strain responses of specimens were calculated by means of the program ADINA. The multiaxial fatigue life prediction was carried out according to von Mises’s equivalent theory. The results from the prediction showed that the equivalent strain range can be served as the valid mechanics for predicting multiaxial high temperature and low cyclic fatigue life.

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