scholarly journals An analytical model to predict strain-hardening behaviour and twin volume fraction in a profoundly twinning magnesium alloy

2019 ◽  
Vol 119 ◽  
pp. 273-290 ◽  
Author(s):  
Sudeep K. Sahoo ◽  
Laszlo S. Toth ◽  
Somjeet Biswas
Keyword(s):  
Magnesium Alloy ◽  
Strain Hardening ◽  
Analytical Model ◽  
Volume Fraction ◽  
Twin Volume Fraction

scholarly journals Iron-chromium-carbon-vanadium white cast irons: Microstructure and properties

2014 ◽  
Vol 68 (4) ◽  
pp. 413-427 ◽  
Author(s):  
Mirjana Filipovic
Keyword(s):  
Fracture Toughness ◽  
Strain Hardening ◽  
Volume Fraction ◽  
Dynamic Fracture Toughness ◽  
M23c6 Carbide ◽  
Cast Irons ◽  
Repeated Impact ◽  
Secondary Carbides ◽  
The Matrix ◽  
Microstructure Parameters

The as-cast microstructure of Fe-Cr-C-V white irons consists of M7C3 and vanadium rich M6C5 carbides in austenitic matrix. Vanadium changed the microstructure parameters of phase present in the structure of these alloys, including volume fraction, size and morphology. The degree of martensitic transformation also depended on the content of vanadium in the alloy. The volume fraction of the carbide phase, carbide size and distribution has an important influence on the wear resistance of Fe-Cr-C-V white irons under low-stress abrasion conditions. However, the dynamic fracture toughness of Fe-Cr-C-V irons is determined mainly by the properties of the matrix. The austenite is more effective in this respect than martensite. Since the austenite in these alloys contained very fine M23C6 carbide particles, higher fracture toughness was attributed to a strengthening of the austenite during fracture. Besides, the secondary carbides which precipitate in the matrix regions also influence the abrasion behaviour. By increasing the matrix strength through a dispersion hardening effect, the fine secondary carbides can increase the mechanical support of the carbides. Deformation and appropriate strain hardening occur in the retained austenite of Fe-Cr-C-V alloys under repeated impact loading. The particles of precipitated M23C6 secondary carbides disturb dislocations movement and contribute to increase the effects of strain hardening in Fe-Cr-C-V white irons.

scholarly journals Nanoparticle amount, and not size, determines chain alignment and nonlinear hardening in polymer nanocomposites

2017 ◽  
Vol 114 (16) ◽  
pp. E3170-E3177 ◽  
Author(s):  
H. Samet Varol ◽  
Fanlong Meng ◽  
Babak Hosseinkhani ◽  
Christian Malm ◽  
Daniel Bonn ◽  
...  
Keyword(s):  
Strain Hardening ◽  
Polymer Nanocomposites ◽  
Nonlinear Elasticity ◽  
Volume Fraction ◽  
Uniaxial Tensile ◽  
Large Strains ◽  
Chain Alignment ◽  
Strain Hardening Behavior ◽  
Polymer Chain Alignment ◽  
Nonlinear Hardening

Polymer nanocomposites—materials in which a polymer matrix is blended with nanoparticles (or fillers)—strengthen under sufficiently large strains. Such strain hardening is critical to their function, especially for materials that bear large cyclic loads such as car tires or bearing sealants. Although the reinforcement (i.e., the increase in the linear elasticity) by the addition of filler particles is phenomenologically understood, considerably less is known about strain hardening (the nonlinear elasticity). Here, we elucidate the molecular origin of strain hardening using uniaxial tensile loading, microspectroscopy of polymer chain alignment, and theory. The strain-hardening behavior and chain alignment are found to depend on the volume fraction, but not on the size of nanofillers. This contrasts with reinforcement, which depends on both volume fraction and size of nanofillers, potentially allowing linear and nonlinear elasticity of nanocomposites to be tuned independently.

Dynamic Compressive Response of Sinusoidal Corrugated Core Sandwich Plates

2018 ◽  
Vol 10 (07) ◽  
pp. 1850075 ◽  
Author(s):  
Jian-Xun Zhang ◽  
Yang Ye ◽  
Qing-Hua Qin ◽  
T. J. Wang
Keyword(s):  
Strain Hardening ◽  
Analytical Model ◽  
Plastic Material ◽  
Deformation Mode ◽  
Numerical Results ◽  
Collapse Mechanism ◽  
Sandwich Plates ◽  
Fe Method ◽  
Compressive Response ◽  
Reaction Forces

In this paper, the dynamic compressive response of metal sinusoidal corrugated core sandwich plates is investigated. The analytical model for the reaction forces of top and bottom face sheets subjected to constant velocity are developed. Finite element (FE) method is carried out to predict the dynamic collapse of metal sinusoidal corrugated cores. Several collapse modes of cores are found in terms of different impact velocity and relative core density. The analytical predications are compared with numerical results, and the analytical model captures numerical results for reaction forces reasonably. The collapse mechanism maps are constructed for sinusoidal corrugated cores with elastic-perfectly plastic material and strain hardening plastic material. The effect of strain rate sensitive on the collapse response is discussed. It is demonstrated that the strain hardening of the metal material increases the dominant deformation mode of the collapse mechanism maps.

scholarly journals Effects of Pre-Strain on the Evolution of Microstructure and Strain Hardening of Extruded Az31 Magnesium Alloy

2017 ◽  
Vol 20 (4) ◽  
pp. 1003-1009
Author(s):  
Lifei Wang ◽  
Miao Cao ◽  
Shuming Yang ◽  
Hua Zhang ◽  
Dongya Wang ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Strain Hardening ◽  
Az31 Magnesium Alloy ◽  
Evolution Of Microstructure

Numerical Simulation and Experimental Verification of Microstructure Evolution during the Seamless Tube Extrusion of Semi-Continuous Casting AZ31 Magnesium Alloy

2017 ◽  
Vol 898 ◽  
pp. 79-85
Author(s):  
Tao Lin ◽  
Ji Xue Zhou ◽  
Bai Chang Ma ◽  
Yun Teng Liu ◽  
Di Zhang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Magnesium Alloy ◽  
Continuous Casting ◽  
Dynamic Recrystallization ◽  
Volume Fraction ◽  
Seamless Tube ◽  
Compression Tests ◽  
Extrusion Speed ◽  
Tube Extrusion ◽  
Az31 Mg Alloy

Based on the stress-strain curves at the temperature of 300-450 °C with strain rate of 0.01-1 s−1 by hot compression tests, the empirical dynamic recrystallization models for the semi-continuous AZ31magnesium alloy were developed. The dynamic recrystallization evolution during the seamless tube extrusion of the AZ31 Mg alloy was simulated by numerical method with the derived models and validated by experiment measurements. The results show that at certain extrusion speed the influence of the extruding temperature on the dynamic recrystallization fraction was significant. With the increase of the extruding temperature the volume fraction of dynamic recrystallization increase obviously. The predicted dynamic recrystallization fraction was in an excellent agreement with the experimental results.

Climb-Enabled Discrete Dislocation Plasticity Analysis of the Deformation of a Particle Reinforced Composite

2015 ◽  
Vol 82 (7) ◽  
Author(s):  
C. Ayas ◽  
L. C. P. Dautzenberg ◽  
M. G. D. Geers ◽  
V. S. Deshpande
Keyword(s):  
Particle Size ◽  
Size Effect ◽  
Strain Hardening ◽  
Volume Fraction ◽  
Dislocation Motion ◽  
Dislocation Climb ◽  
Discrete Dislocation ◽  
Dislocation Plasticity ◽  
Wall Structures ◽  
The Matrix

The shear deformation of a composite comprising elastic particles in a single crystal elastic–plastic matrix is analyzed using a discrete dislocation plasticity (DDP) framework wherein dislocation motion occurs via climb-assisted glide. The topology of the reinforcement is such that dislocations cannot continuously transverse the matrix by glide-only without encountering the particles that are impenetrable to dislocations. When dislocation motion is via glide-only, the shear stress versus strain response is strongly strain hardening with the hardening rate increasing with decreasing particle size for a fixed volume fraction of particles. This is due to the formation of dislocation pile-ups at the particle/matrix interfaces. The back stresses associated with these pile-ups result in a size effect and a strong Bauschinger effect. By contrast, when dislocation climb is permitted, the dislocation pile-ups break up by forming lower energy dislocation wall structures at the particle/matrix interfaces. This results in a significantly reduced size effect and reduced strain hardening. In fact, with increasing climb mobility an “inverse size” effect is also predicted where the strength decreases with decreasing particle size. Mass transport along the matrix/particle interface by dislocation climb causes this change in the response and also results in a reduction in the lattice rotations and density of geometrically necessary dislocations (GNDs) compared to the case where dislocation motion is by glide-only.

Research on the Microstructures and Mechanical Properties of Annealed Cold Upsetting AZ31 Magnesium Alloy

2009 ◽  
Vol 610-613 ◽  
pp. 826-830
Author(s):  
Tian Mo Liu ◽  
Wei Hui Hu ◽  
Qing Liu
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Annealing Temperature ◽  
Volume Fraction ◽  
Cold Upsetting ◽  
Cast Magnesium Alloys ◽  
Microstructures And Mechanical Properties ◽  
Cast Magnesium

The microstructures and mechanical properties of cold upsetting magnesium alloys were investigated upon anneal under different conditions. The results show that a large amount of twins were observed in the original grains of cold upsetting AZ31 magnesium alloys. The twins disappeared gradually and recrystal grains formed after anneal. The volume fraction of the recrystal grains increases as the strain of samples rises. Recrystal grain size grows large with the elevated annealing temperature. Recrystal grain size reduces at first and then grows as the annealing time is prolonged. In addition, compared with as-cast magnesium alloys, the yield strength of cold upsetting samples increase apparently due to grain refinement after anneals.

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