scholarly journals Autowave Criteria of Fracture and Plastic Strain Localization of Zirconium Alloys

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 95
Author(s):  
Lev B. Zuev ◽  
Svetlana A. Barannikova ◽  
Dina V. Orlova
Keyword(s):  
Plastic Strain ◽  
Cold Rolling ◽  
Strain Distribution ◽  
Ultrasound Velocity ◽  
Zirconium Alloys ◽  
Joint Analysis ◽  
Deformation Bands ◽  
Localized Deformation ◽  
Stress Strain ◽  
Zone Length

Plastic deformation and fracture of Zr–1% Nb alloys exposed to quasi-static tensile testing have been studied via a joint analysis of stress-strain curves, ultrasound velocity and double-exposure speckle photographs. The possibilities of ductility evaluation through the εxx strain distribution in thin-walled parts of zirconium alloys are shown in this paper. The stress-strain state of zirconium alloys in a cold rolling site is investigated considering the development of localized deformation bands and changes in ultrasound velocity. It is established that the transition from the upsetting to the reduction region is accompanied by the significant exhaustion of the plasticity margin of the material; therefore, the latter is more prone to fracture in this zone exactly. It is shown that traditional methods estimating the plasticity margin from the mechanical properties cannot reveal this region, requiring a comprehensive study of macroscopically localized plastic strain in combination with acoustic measurements. In particular, the multi-pass cold rolling of Zr alloys includes various localized deformation processes that can result in the formation of localized plasticity autowaves. Recommendations for strain distribution division over the deformation zone length in the alloy in the pilger roll grooves are provided as well.

Digital image correlation shows localized deformation bands in inelastic loading of fibrolamellar bone

2009 ◽  
Vol 24 (2) ◽  
pp. 421-429 ◽  
Author(s):  
Gunthard Benecke ◽  
Michael Kerschnitzki ◽  
Peter Fratzl ◽  
Himadri S. Gupta
Keyword(s):  
Plastic Strain ◽  
Tensile Deformation ◽  
Image Correlation ◽  
Correlation Technique ◽  
Length Scale ◽  
Strain Rates ◽  
Deformation Bands ◽  
Localized Deformation ◽  
High Deformation ◽  
Multiple Regions

Irreversible or plastic deformation in bone is associated with both permanent plastic strain as well as localized microdamage. Whereas mechanisms at the molecular and mesoscopic level have been proposed to explain aspects of irreversible deformation, a quantitative correlation of mechanical yielding, microstructural deformation, and macroscopic plastic strain does not exist. To address this issue, we developed and applied a two-dimensional image correlation technique to the tensile deformation of bovine fibrolamellar bone, to determine the spatial distribution of strain fields at the length scale of 10 μm to 1 mm in bone during irreversible tensile deformation. We find that tensile deformation is relatively homogeneous in the elastic regime and starts at the yield point, showing regions of locally higher strain. Multiple regions of high deformation can exist at the same time over a length scale of 1 to 10 mm. Macroscopic fracture always occurs at one of the locally highly deformed regions, but the selection of which region cannot be predicted. Locally, strain rates can be enhanced by a factor of 3 to 10 over global strain rates in the highly deformed zones and are lower but always positive in all other regions. Light microscopic imaging shows the onset of structural “banding” in the regions of high deformation, which is most likely correlated to microstructural damage at the inter- and intrafibrillar level.

Deformation Behavior and Plastic Strain Localization of Nanostructured Materials Produced by Severe Plastic Deformation

2009 ◽  
Vol 633-634 ◽  
pp. 107-119 ◽  
Author(s):  
Evgeny V. Naydenkin ◽  
Galina P. Grabovetskaya
Keyword(s):  
Plastic Deformation ◽  
Plastic Strain ◽  
Severe Plastic Deformation ◽  
Strain Localization ◽  
Deformation Behavior ◽  
Grain Boundary Sliding ◽  
Deformation Bands ◽  
Localized Deformation ◽  
Plastic Strain Localization ◽  
Structure Heterogeneity

The literature on the deformation behavior and plastic strain localization inherent to nanostructured metallic polycrystals produced by severe plastic deformation techniques is reviewed. The effects of the texture, structure heterogeneity and state of grain boundaries on the special features and evolution of mesoscopic and macroscopic localized deformation bands are investigated. The role of grain-boundary sliding in the development of mesoscopic plastic deformation bands is discussed.

Effects of Cold-Rolling Reduction on Microstructure and Mechanical Properties of Ti50Zr30Nb10Ta10 Alloy

2016 ◽  
Vol 849 ◽  
pp. 376-381
Author(s):  
Ming Long Li ◽  
Yu Jie Geng ◽  
Chen Chen ◽  
Shu Jie Pang ◽  
Tao Zhang
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
Plastic Strain ◽  
Cold Rolling ◽  
Reduction Ratio ◽  
High Fracture ◽  
Dendrite Structure ◽  
Microstructure And Mechanical Properties ◽  
Cold Rolling Reduction ◽  
Cold Rolled

The effects of cold-rolling with different reduction ratios of 70%-90% on the microstructure and mechanical properties of Ti50Zr30Nb10Ta10 alloy were investigated. It was found that the β-Ti phase in this alloy was stable under cold-rolling. With the increase in reduction ratio from 70% to 90%, the microstructure of the alloys evolved from deformed dendrite structure to fiber-like structure. The alloy cold-rolled with the reduction ratio of 70% exhibited optimum mechanical properties of combined high fracture strength of 1012 MPa and plastic strain of 10.1%, which are closely correlated with the dendrite structure of the alloy. It is indicated that the proper cold-rolling is an effective way to improve the mechanical properties of the titanium alloy.

scholarly journals Studying the effect of elastic-plastic strain and hydrogen sulphide on the magnetic behaviour of pipe steels as applied to their testing

2018 ◽  
Vol 145 ◽  
pp. 05003
Author(s):  
Anna Povolotskaya ◽  
Eduard Gorkunov ◽  
Sergey Zadvorkin ◽  
Igor Veselov
Keyword(s):  
Plastic Strain ◽  
Initial Stress ◽  
Elastic Deformation ◽  
Hydrogen Sulphide ◽  
Strain State ◽  
Pipe Steel ◽  
Magnetic Behaviour ◽  
Pipe Steels ◽  
Stress Strain ◽  
Stress Strain State

The paper reports results of magnetic measurements made on samples of the 12GB pipe steel (strength group X42SS) designed for producing pipes to be used in media with high hydrogen sulphide content, both in the initial state and after exposure to hydrogen sulphide, for 96, 192 and 384 hours under uniaxial elastic-plastic tension. At the stage of elastic deformation there is a unique correlation between the coercive force measured on a minor hysteresis loop in weak fields and tensile stress, which enables this parameter to be used for the evaluation of elastic stresses in pipes made of the 12 GB pipe steel under different conditions, including a hydrogen sulphide containing medium. The effect of the value of preliminary plastic strain, viewed as the initial stress-strain state, on the magnetic behaviour of X70 pipe steels under elastic tension and compression is studied. Plastic strain history affects the magnetic behaviour of the material during subsequent elastic deformation since plastic strain induces various residual stresses, and this necessitates taking into account the initial stress-strain state of products when developing magnetic techniques for the determination of their stress-strain parameters during operation.

Local Texture Evolution by Rate-Independent Polycrystal Model Allowing for Coordination of Interacting Crystals

2005 ◽  
Vol 495-497 ◽  
pp. 965-970
Author(s):  
A.A. Zisman ◽  
Nikolay Y. Zolotorevsky ◽  
N.Yu. Ermakova
Keyword(s):  
Experimental Data ◽  
Plastic Strain ◽  
Strain Distribution ◽  
Texture Evolution ◽  
Spatial Coordination ◽  
Local Texture ◽  
Plastic Strain Distribution ◽  
Simulation Results

A rate-independent polycrystal model, allowing for the shape and spatial coordination of neighboring constitutive crystals and for the plastic strain distribution among them, has been used to simulate the local texture evolution in an Al polycrystal under compression. The simulation results compare favourably to relevant experimental data and show the reorientation path of each crystal to strongly depend on orientations of its immediate neighbors.

Routes towards Novel Active Pressure Sensors in SOI Technology

2011 ◽  
Vol 276 ◽  
pp. 145-155
Author(s):  
Benoit Olbrechts ◽  
Bertrand Rue ◽  
Thomas Pardoen ◽  
Denis Flandre ◽  
Jean Pierre Raskin
Keyword(s):  
Finite Elements ◽  
Strain Distribution ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Stress Strain ◽  
Pressure Transducers ◽  
Active Devices ◽  
Active Pressure ◽  
Soi Technology

In this paper, novel pressure sensors approach is proposed and described. Active devices and oscillating circuits are directly integrated on very thin dielectric membranes as pressure transducers. Involved patterning of the membrane is supposed to cause a drop of mechanical robustness. Finite elements simulations are performed in order to better understand stress/strain distribution and as an attempt to explain the early burst of patterned membranes. Smart circuit designs are reported as solutions with high sensitivity and reduced footprint on membranes.

Plastic Strain Distribution at the Tips of Propagating Fatigue Cracks

1976 ◽  
Vol 98 (1) ◽  
pp. 24-29 ◽  
Author(s):  
D. L. Davidson ◽  
J. Lankford
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Crack ◽  
Plastic Strain ◽  
Plastic Zone ◽  
Strain Distribution ◽  
Dimensionless Parameter ◽  
Fatigue Cracks ◽  
Crack Tip ◽  
Cyclic Plastic Zone ◽  
Plastic Zones

The techniques of selected area electron channeling and positive replica examination have been used to study the plastic zones attending fatigue crack propagation in 304 SS, 6061-T6 aluminum alloy, and Fe-3Si steel. These observations allowed the strain distribution at the crack tip to be determined. The results indicate that the concepts of a monotonic and a cyclic plastic zone are essentially correct, with the strains at demarcation between these two zones being 3 to 6 percent. Strain distribution varies as r−1/2 in the cyclic zone and as ln r in the monotonic plastic zone. The strain distributions for all materials studied may be made approximately coincident by using a dimensionless parameter related to distance from the crack tip.

Stress and Strain Distribution in the Upsetting Process

2021 ◽  
pp. 288-301
Author(s):  
Japheth Obiko ◽  
Fredrick Madaraka Mwema
Keyword(s):  
Finite Element ◽  
Strain Distribution ◽  
Metal Flow ◽  
Stress Strain ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Contact Surfaces ◽  
Stress Behaviour ◽  
Stress And Strain Distribution ◽  
Forging Load

Numerical simulation of metal flow behaviour was studied using DeformTM3D software. The simulation process was done on X20 steel taken from the software database at 1073-1273K temperature, 10mm/s die speed, and 67% height reduction. From the simulation results, forging load, damage, and stress/strain distributions were obtained. The results show that the forging load increased with a decrease in temperature or decreased with an increase in temperature. The maximum damage values increased as the temperature increased. The obtained maximum damage values were 0.42 (1073K), 0.43 (1173K), and 0.45 (1273K). The damage distribution was inhomogeneous in the deformed cylinder. The stress/strain distributions were inhomogeneous in the deformed cylinder. The location of the maximum strain was at the centre of the deformed cylinder while the maximum stress occurred at the die-cylinder contact surfaces. The study showed that flow stress behaviour can be predicted using finite element method. This shows the feasibility of applying the finite element analysis to analyse the forging process.

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