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.

scholarly journals Effect of forging on the low cycle fatigue behavior of cast AZ31B alloy

2017 ◽  
Vol 706 ◽  
pp. 342-356 ◽  
Author(s):  
D. Toscano ◽  
S.K. Shaha ◽  
B. Behravesh ◽  
H. Jahed ◽  
B. Williams
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Az31b Alloy

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.

Controlling the Microstructure and Texture Using Multidirectional Forging (MDF) to Develop a Low Corrosion Rate Mg Alloy

CORROSION ◽  
10.5006/3485 ◽  
2020 ◽  
Vol 76 (8) ◽  
pp. 750-765 ◽  
Author(s):  
Ahmad Bahmani ◽  
Kwang Seon Shin
Keyword(s):  
Electron Microscopy ◽  
Corrosion Rate ◽  
Uniform Distribution ◽  
Electron Backscatter Diffraction ◽  
Mg Alloy ◽  
Second Phase ◽  
Compression Tests ◽  
Multidirectional Forging ◽  
Transmission Electron ◽  
Tension And Compression

A new Mg alloy was cast, then extruded, and finally multidirectionally forged (MDF) at 180°C (MDF180) and 300°C (MDF300). The corrosion behavior was evaluated using electrochemical and immersion techniques. The mechanical property was assessed using tension and compression tests. The microstructures were analyzed using optical microscopy, scanning electron microscopy, transmission electron microscopy, x-ray diffraction (XRD), and thermodynamic calculations, while texture was studied by XRD and electron backscatter diffraction. Results indicated that due to grain refinement and good distribution of second phase after MDF, yield strength as well as elongation were improved. The corrosion rates were reduced for MDF180 due to the uniform distribution of the second phase along with uniform distribution of grains. Corrosion rate was more reduced for MDF300 due to dissolution of second phase and elimination of worked grains.

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.

Modelling the asymmetric tension–compression properties of additively manufactured alloys using continuum damage mechanics

2021 ◽  
pp. 146442072110134
Author(s):  
A Nayebi ◽  
H Rokhgireh ◽  
M Araghi ◽  
M Mohammadi
Keyword(s):  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Element Model ◽  
Continuum Damage ◽  
Compression Tests ◽  
Compression Properties ◽  
Mechanics Model ◽  
Stress Components ◽  
Tension And Compression ◽  
Closure Effect

Additively manufactured parts often comprise internal porosities due to the manufacturing process, which needs to be considered in modelling their mechanical behaviour. It was experimentally shown that additively manufactured parts’ tensile and compressive mechanical properties are different for various metallic alloys. In this study, isotropic continuum damage mechanics is used to model additively manufactured alloys’ tension and compression behaviours. Compressive stress components can shrink discontinuities present in additively manufactured alloys. Therefore, the crack closure effect was employed to describe different behaviours during uniaxial tension and compression tests. A finite element model embedded in an ABAQUS’s UMAT format was developed to account for the isotropic continuum damage mechanics model. The numerical results of tension and compression tests were compared with experimental observations for additively manufactured maraging steel, AlSi10Mg and Ti-6Al-4V. Stress–strain curves in tension and compression of these alloys were obtained using the continuum damage mechanics model and compared well with the experimental results.

scholarly journals Influence of Cold Rotary Swaging on Microstructure and Uniaxial Mechanical Behavior in Alloy 718

2021 ◽  
Author(s):  
Alexander Klumpp ◽  
Alexander Kauffmann ◽  
Sascha Seils ◽  
Stefan Dietrich ◽  
Volker Schulze
Keyword(s):  
Mechanical Behavior ◽  
Electron Backscatter Diffraction ◽  
Moderate Increase ◽  
Alloy 718 ◽  
Pronounced Increase ◽  
Rotary Swaging ◽  
Elastic Range ◽  
Nickel Based Superalloy ◽  
Tempering Treatment ◽  
Tension And Compression

AbstractIn this study, the influence of cold rotary swaging on microstructure and mechanical properties of the precipitation-strengthened nickel-based superalloy 718 (Alloy 718) was investigated. The initial stages of work-hardening were characterized by means of microhardness, electron backscatter diffraction (EBSD), and X-ray diffraction (XRD) analyses. Furthermore, attention was devoted to the mechanical behavior at ambient and elevated temperature (550 °C) in uniaxial tension and compression. Rotary swaging to different true strains of maximum $$\varphi = 0.91$$ φ = 0.91 caused a moderate increase of microhardness and enhanced markedly the load-bearing capacity in tension, giving rise to yield strength beyond 2000 MPa. The mechanical strength $$R_{p0.2}$$ R p 0.2 in tension subsequent to rotary swaging perfectly correlates with increasing dislocation density $$\rho $$ ρ estimated from XRD in the form of a Taylor-like relationship $$R_{p0.2} \propto \sqrt{\rho }$$ R p 0.2 ∝ ρ . In compression, transient stress–strain evolution without the occurrence of a clear elastic range and distinct yield phenomenon was observed. Restoration of the elastic range, accompanied by a pronounced increase of microhardness, was obtained by a post-swaging tempering treatment at 600 °C.

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 Effect of Build Orientation on the Microstructure, Mechanical and Corrosion Properties of a Biodegradable High Manganese Steel Processed by Laser Powder Bed Fusion

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 944
Author(s):  
Martin Otto ◽  
Stefan Pilz ◽  
Annett Gebert ◽  
Uta Kühn ◽  
Julia Hufenbach
Keyword(s):  
Electron Backscatter Diffraction ◽  
Longitudinal Axis ◽  
Manganese Steel ◽  
Compressive Yield Strength ◽  
Powder Bed Fusion ◽  
Compression Tests ◽  
Laser Powder Bed Fusion ◽  
Corrosion Properties ◽  
Powder Bed ◽  
Manufacturing Technologies

In the last decade, additive manufacturing technologies like laser powder bed fusion (LPBF) have emerged strongly. However, the process characteristics involving layer-wise build-up of the part and the occurring high, directional thermal gradient result in significant changes of the microstructure and the related properties compared to traditionally fabricated materials. This study presents the influence of the build direction (BD) on the microstructure and resulting properties of a novel austenitic Fe‑30Mn‑1C‑0.02S alloy processed via LPBF. The fabricated samples display a {011} texture in BD which was detected by electron backscatter diffraction. Furthermore, isolated binding defects could be observed between the layers. Quasi-static tensile and compression tests displayed that the yield, ultimate tensile as well as the compressive yield strength are significantly higher for samples which were built with their longitudinal axis perpendicular to BD compared to their parallel counterparts. This was predominantly ascribed to the less severe effects of the sharp-edged binding defects loaded perpendicular to BD. Additionally, a change of the Young’s modulus in dependence of BD could be demonstrated, which is explained by the respective texture. Potentiodynamic polarization tests conducted in a simulated body fluid revealed only slight differences of the corrosion properties in dependence of the build design.

Characteristics of the Deformed and Recrystallised Grains Obtained after Hot Plane Strain Compression of a Model Fe-30wt%Ni Alloy

2004 ◽  
Vol 467-470 ◽  
pp. 21-26 ◽  
Author(s):  
F. Bai ◽  
P. Cizek ◽  
Eric J. Palmiere ◽  
Mark W. Rainforth
Keyword(s):  
Plane Strain ◽  
Crystallographic Texture ◽  
Hot Deformation ◽  
Electron Backscatter Diffraction ◽  
Orientation Dependence ◽  
Plane Strain Compression ◽  
Formation Mechanisms ◽  
Subgrain Structure ◽  
Compression Tests ◽  
Texture Characteristics

The development of physically-based models of microstructural evolution during hot deformation of metallic materials requires knowledge of the grain/subgrain structure and crystallographic texture characteristics over a range of processing conditions. A Fe-30wt%Ni based alloy, retaining a stable austenitic structure at room temperature, was used for modelling the development of austenite microstructure during hot deformation of conventional carbon-manganese steels. A series of plane strain compression tests was carried out at a temperature of 950 °C and strain rates of 10 s-1 and 0.1 s-1 to several strain levels. Evolution of the grain/subgrain structure and crystallographic texture was characterised in detail using quantitative light microscopy and highresolution electron backscatter diffraction. Crystallographic texture characteristics were determined separately for the observed deformed and recrystallised grains. The subgrain geometry and dimensions together with the misorientation vectors across sub-boundaries were quantified in detail across large sample areas and the orientation dependence of these characteristics was determined. Formation mechanisms of the recrystallised grains were established in relation to the deformation microstructure.

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