The Influence of Microtexture on Fatigue Behavior in Titanium Alloys

1997 ◽  
Vol 3 (S2) ◽  
pp. 571-572 ◽  
Author(s):  
A. P. Woodfield ◽  
J. A. Sutliff
Keyword(s):  
Cross Sections ◽  
Electron Backscatter Diffraction ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Peak Stress ◽  
Stress Axis ◽  
Fracture Plane ◽  
Fracture Surfaces ◽  
Orientation Imaging ◽  
Wave Forms

Automated electron backscatter diffraction pattern (EBSP) measurements were conducted in an attempt to relate low cycle fatigue (LCF) behavior to underlying microtexture in alpha-beta forged and heat treated Ti-6242 materials. Conventional load control, R=0 LCF tests were conducted with two wave forms, 30 cycles per minute (30 cpm), and 2 minute hold at peak stress, (dwell). The fracture surfaces and adjacent microstructures of the LCF specimens were examined using light microscopy, scanning electron microscopy (SEM), and orientation imaging using automated EBSP.Fracture surfaces of dwell LCF specimens frequently contained large macroscopically flat, shiny facets, while 30 cpm specimens showed no such evidence of facets. Additionally, the dwell LCF specimens that contained facets had very low lives, typically around 1000 cycles at 126 ksi maximum stress. EBSP measurements directly on the facets, and on cross-sections through the facets revealed that the facet fracture plane was on, or close to (0001) of the primary alpha grains, Fig. 1, and was approximately perpendicular to the stress axis.

Low Cycle Fatigue Behavior of As-Extruded AZ31 Magnesium Alloy

2011 ◽  
Vol 686 ◽  
pp. 202-207
Author(s):  
Ping Li Mao ◽  
Zheng Liu ◽  
Yang Li ◽  
Li Jia Chen
Keyword(s):  
Magnesium Alloy ◽  
Strain Amplitude ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Az31 Alloy ◽  
Plastic Strain Amplitude ◽  
Az31 Magnesium Alloy ◽  
Total Strain Amplitude ◽  
Fracture Surfaces

The investigation on fatigue behavior and fracture surfaces of fatigued specimens of as-extruded AZ31 magnesium alloy can provide a reliable theoretical foundation for both fatigue resistant design and reasonable application of magnesium alloys. Through total-strain-amplitude controlled fatigue tests and analysis on fracture surfaces of fatigued specimens, the behavior of cyclic stress response and fatigue life as well as fracture mechanism were identified for as-extruded AZ31 magnesium alloy. The experimental results show that the extruded AZ31 alloy exhibits significant cyclic strain hardening, the relation between elastic strain amplitude, plastic strain amplitude and reversals to failure can be described by Basquin and Coffin-Manson equations respectively. In addition, it has been found that fatigue cracks initiate and propagate in a transgranular mode.

scholarly journals Low-cycle Fatigue Behavior and Constitutive Relations for a Ferritic Stainless Steel at Elevated Temperatures

2020 ◽  
pp. 34-46
Author(s):  
S. M. Humayun Kabir ◽  
Tae-In Yeo
Keyword(s):  
Numerical Simulation ◽  
Stainless Steel ◽  
Ferritic Stainless Steel ◽  
Constitutive Equations ◽  
Elevated Temperatures ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Constitutive Relations ◽  
Peak Stress ◽  
Effect Of Temperature

In this paper, the tensile and strain-controlled cyclic deformation behavior of a ferritic stainless steel which is developed for the exhaust manifold of automobiles is evaluated experimentally at different temperatures. The effect of temperature on monotonic tensile responses such as yield strength and ultimate tensile strength and the effect of temperature and strain amplitude on the evolution of peak stress are assessed. The objective of this study is also to reveal the mixed mode of cyclic hardening–softening behavior of the ferritic stainless steel under strain-controlled fatigue test conditions. A parameter, critical accumulated plastic strain, is introduced to the constitutive equations for the material for describing the hardening - softening responses. The nonlinear constitutive equations for describing the cyclic responses are implemented into Finite Element code using determined parameters for obtaining numerical simulation. The stabilized hysteretic responses obtained from experiment and predicted from numerical simulation are compared and found to be realistic.

Grain Size Effect on Low Cycle Fatigue Behavior of High Strength Structural Materials

2016 ◽  
Vol 258 ◽  
pp. 269-272
Author(s):  
Ryuichiro Ebara
Keyword(s):  
Grain Size ◽  
Fatigue Strength ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
High Strength ◽  
Grain Size Effect ◽  
Cycle Fatigue ◽  
Fracture Surfaces ◽  
Fine Grain ◽  
Number Of Cycles

This paper presents grain size effect on low cycle fatigue behavior of high strength maraging steel with gain size of 20,60 and 100μm and Ti-6Al-4V alloy with grain size of 0.5,1.4 and 5.1μm. Low cycle fatigue strength of the maraging steel depends on grain size in number of cycles up to 103.The smaller the grain size, the higher the low cycle fatigue strength was. Quasci-cleavage fracture surfaces were predominant for material with grain size of 20μm,while intergranular fracture surfaces were predominant for materials with larger grain size in number of cycles lower than 60. Striation was predominant for all tested materials in number of cycles higher than 60.Low cycle fatigue strength of Ti-6Al-4V alloy also depends on grain size in number of cycles up to 104. Grain size dependent transgranular fracture surfaces were predominant for materials with ultra-fine grain size of 0.5μm and fine grain size of 1.4μm.

scholarly journals Load Direction-Dependent Influence of Forming-Induced Initial Damage on the Fatigue Performance of 16MnCrS5 Steel

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2680
Author(s):  
Kerstin Moehring ◽  
Frank Walther
Keyword(s):  
Cross Sections ◽  
Damage Evolution ◽  
Electron Backscatter Diffraction ◽  
Extrusion Direction ◽  
Crack Arrest ◽  
Fatigue Performance ◽  
Stress Axis ◽  
Initial Damage ◽  
Compressive Loads ◽  
Cyclic Damage

Forming processes influence the mechanical properties of manufactured workpieces in general and by means of forming-induced initial damage in particular. The effect of the latter on performance capability is the underlying research aspect for the investigations conducted. In order to address this aspect, fatigue tests under compressive, tensile and compressive-tensile loads were set-up with discrete block-by-block increased amplitudes and constant amplitudes, and performed up to fracture or distinct lifetimes. Aiming at the correlation of the macroscale mechanical testing results at the mesoscale, intensive metallographic investigations of cross-sections using the microscopical methods of secondary electron analysis, energy dispersive spectroscopy and electron backscatter diffraction were performed. Thereby, the correlation of forming-induced initial damage and fatigue performance was determined, the relevance of compressive loads for the cyclic damage evolution was shown, and material anisotropy under compressive loads was indicated. Finally, the need was addressed to perform further investigations regarding crack propagations and crack arrest investigations in order to clarify the mechanism by which initial damage affects cyclic damage evolution. The relevance of the principal stress axis relative to the extrusion direction was emphasized and used as the basis of an argument for investigations under load paths with different stress directions.

scholarly journals Low-Cycle Fatigue Behavior of Hot-Bent Basal Textured AZ31B Wrought Magnesium Alloy

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1004
Author(s):  
Anton Nischler ◽  
Josef Denk ◽  
Holger Saage ◽  
Hubert Klaus ◽  
Otto Huber
Keyword(s):  
Electron Backscatter Diffraction ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Diffraction Method ◽  
Compression Tests ◽  
Young’S Moduli ◽  
Schmid Factor ◽  
Tension And Compression ◽  
Az31b Alloy ◽  
Twin Roll Cast

In the recent past, several researchers have successfully modeled the complex fatigue behavior of planar twin-roll cast AZ31B alloy sheets. Complex components are usually hot-bent, whereby the microstructure in the hot-bent areas changes significantly. However, studies on the fatigue behavior of hot-bent magnesium alloys are currently lacking. Therefore, a novel, uniaxial hot-bent specimen was developed and optimized with finite element method simulations. Microstructural analyses with the electron backscatter diffraction method reveal that the hot-bending process changes the texture and increases the Schmid factor for basal slip in rolling and transverse direction of the sheet. In the subsequent quasi-static tension and compression tests, anisotropic and asymmetric yield stresses, lower Young’s moduli compared with the as-received material and macroscopic bands of twinned grains are obtained. Finally, the study proves that the recently proposed concept of highly strained volume can accurately estimate the lifetime, even by combining the as-received and hot-bent material in one fatigue model.

Cross Section Analysis of Cu Filled TSVs Based on High Throughput Plasma-FIB Milling

2012 ◽  
Author(s):  
Frank Altmann ◽  
Jens Beyersdorfer ◽  
Jan Schischka ◽  
Michael Krause ◽  
German Franz ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
High Throughput ◽  
Cross Sections ◽  
Electron Backscatter Diffraction ◽  
Grain Structure ◽  
Electron Backscatter ◽  
Section Surface ◽  
Backscatter Diffraction ◽  
Section Analysis

Abstract In this paper the new Vion™ Plasma-FIB system, developed by FEI, is evaluated for cross sectioning of Cu filled Through Silicon Via (TSV) interconnects. The aim of the study presented in this paper is to evaluate and optimise different Plasma-FIB (P-FIB) milling strategies in terms of performance and cross section surface quality. The sufficient preservation of microstructures within cross sections is crucial for subsequent Electron Backscatter Diffraction (EBSD) grain structure analyses and a high resolution interface characterisation by TEM.

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

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.

scholarly journals Experimental and Computational Approach to Fatigue Behavior of Polycrystalline Tantalum

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 416 ◽  
Author(s):  
Damien Colas ◽  
Eric Finot ◽  
Sylvain Flouriot ◽  
Samuel Forest ◽  
Matthieu Mazière ◽  
...  
Keyword(s):  
Free Surface ◽  
Low Cycle Fatigue ◽  
Large Strain ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Field Measurements ◽  
Test Sample ◽  
Lattice Rotation ◽  
Element Simulation ◽  
Crack Initiation Criterion

This work provides an experimental and computational analysis of low cycle fatigue of a tantalum polycrystalline aggregate. The experimental results include strain field and lattice rotation field measurements at the free surface of a tension–compression test sample after 100, 1000, 2000, and 3000 cycles at ±0.2% overall strain. They reveal the development of strong heterogeneites of strain, plastic slip activity, and surface roughness during cycling. Intergranular and transgranular cracks are observed after 5000 cycles. The Crystal Plasticity Finite Element simulation recording more than 1000 cycles confirms the large strain dispersion at the free surface and shows evidence of strong local ratcheting phenomena occurring in particular at some grain boundaries. The amount of ratcheting plastic strain at each cycle is used as the main ingredient of a new local fatigue crack initiation criterion.

scholarly journals Low Cycle Fatigue Characteristics of Oxygen-Free Copper for Electric Power Equipment

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4237
Author(s):  
Takuma Tanaka ◽  
Togo Sugioka ◽  
Tatsuya Kobayashi ◽  
Ikuo Shohji ◽  
Yuya Shimada ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Electric Power ◽  
Stress Amplitude ◽  
Low Cycle Fatigue ◽  
Ebsd Analysis ◽  
Fatigue Properties ◽  
Power Equipment ◽  
Cycle Fatigue ◽  
Fracture Surfaces ◽  
Heat Treated

The effect of heat treatment on tensile and low cycle fatigue properties of the oxygen-free copper for electric power equipment was investigated. The heat treatment at 850 °C for 20 min, which corresponds to the vacuum brazing process, caused the grain growth and relaxation of strain by recrystallization, and thus, the residual stress in the oxygen-free copper was reduced. The tensile strength and 0.2% proof stress were decreased, and elongation was increased by the heat treatment accompanying recrystallization. The plastic strain in the heat-treated specimen was increased compared with that in the untreated specimen under the same stress amplitude condition, and thus, the low cycle fatigue life of the oxygen-free copper was degraded by the heat treatment. Striation was observed in the crack initiation area of the fractured surface in the case of the stress amplitude less than 100 MPa regardless of the presence of the heat treatment. With an increase in the stress amplitude, the river pattern and the quasicleavage fracture were mainly observed in the fracture surfaces of the untreated specimens, and they were observed with striations in the fracture surfaces of the heat-treated ones. The result of the electron backscattered diffraction (EBSD) analysis showed that the grain reference orientation deviation (GROD) map was confirmed to be effective to investigate the fatigue damage degree in the grain by low cycle fatigue. In addition, the EBSD analysis revealed that the grains were deformed, and the GROD value reached approximately 28° in the fractured areas of heat-treated specimens after the low cycle fatigue test.

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