Effect of stress state on cavitation and hot forming limits of a coarse-grained Al5052 alloy

2002 ◽  
Vol 52 (1-2) ◽  
pp. 62-68 ◽  
Author(s):  
K.K Chow ◽  
K.C Chan
Keyword(s):  
Stress State ◽  
Hot Forming ◽  
Coarse Grained ◽  
Forming Limits

scholarly journals Deformation mechanisms and plasticity of ultrafine-grained Al under complex stress state revealed by digital image correlation technique

2021 ◽  
Vol 10 (1) ◽  
pp. 73-86
Author(s):  
Yonghao Zhao ◽  
Yanglin Gu
Keyword(s):  
Stress State ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Curve ◽  
Complex Stress ◽  
Complex Stress State ◽  
Image Correlation ◽  
Coarse Grained ◽  
Correlation Technique ◽  
Ultrafine Grained

Abstract Conventional engineering stress–strain curve could not accurately describe the local deformability of the tensile necking part because the strain is calculated by assuming that the tensile specimen was deformed uniformly. In this study, we used 3D optical measuring digital image correlation to systematically measure the full strain field and actual flow stress in the necking region of ultrafine-grained (UFG) Al. The post-necking elongation and strain hardening exponent of the UFG Al were measured as 80% and 0.10, slightly smaller than those of the coarse-grained Al (117% and 0.28), suggesting the high plastic deformability of the UFG Al under complex stress state. Microstructural studies revealed the shear and ductile fracture, numerous micro-shear bands, and elongated UFG grains in the UFG Al, which are controlled by cooperative grain boundary sliding and multiple dislocation slips.

The effects of strain and stress state in hot forming of mg AZ31 sheet

2012 ◽  
pp. 301-306 ◽  
Author(s):  
Paul A. Sherek ◽  
Alexander J. Carpenter ◽  
Louis G. Hector ◽  
Paul E. Krajewski ◽  
Jon T. Carter ◽  
...  
Keyword(s):  
Stress State ◽  
Hot Forming ◽  
Az31 Sheet

Investigation on hot forming limits of high strength steel 22MnB5

2010 ◽  
Vol 49 (2) ◽  
pp. 326-332 ◽  
Author(s):  
Junying Min ◽  
Jianping Lin ◽  
Jiayue Li ◽  
Wenhua Bao
Keyword(s):  
High Strength Steel ◽  
High Strength ◽  
Hot Forming ◽  
Forming Limits

The Effects of Strain and Stress State in Hot Forming of Mg AZ31 Sheet

2012 ◽  
pp. 301-306 ◽  
Author(s):  
Paul A. Sherek ◽  
Alexander J. Carpenter ◽  
Louis G. Hector ◽  
Paul E. Krajewski ◽  
Jon T. Carter ◽  
...  
Keyword(s):  
Stress State ◽  
Hot Forming ◽  
Az31 Sheet

Microstructural Evolution of an Ultrafine-grained Cryomilled Al 5083 Alloy During Thermomechanical Processing

2005 ◽  
Vol 20 (8) ◽  
pp. 2117-2126 ◽  
Author(s):  
David Witkin ◽  
Bing Q. Han ◽  
Enrique J. Lavernia
Keyword(s):  
Grain Size ◽  
Stress State ◽  
Thermomechanical Processing ◽  
Extrusion Process ◽  
Coarse Grained ◽  
Duplex Microstructure ◽  
Ultrafine Grained ◽  
Average Grain Size ◽  
Coarse Grains ◽  
Al 5083 Alloy

The microstructural changes in cryomilled and consolidated Al 5083 following compression testing at several temperatures are described. Prior to testing, the material had an average grain size of approximately 138 nm and exhibited a duplex microstructure, containing coarse grains between 500 and 2000 nm. After uniaxial compressive deformation at temperatures between 423 and 573 K (0.49–0.66 Tm), the average grain size increased to between 200 and 300 nm, consistent with the average grain size of extrusions formed from the same material at similar temperatures. The similarity in grain size distribution following uniaxial compression or extrusion despite differences in total strain and stress state imposed by each indicates that much of the deformation in the extrusion process occurs in coarse-grained regions.

scholarly journals Experimental study on permanent deformation characteristics of coarse-grained soil under repeated dynamic loading

2021 ◽  
Author(s):  
Huihao Mei ◽  
Sajjad Satvati ◽  
Wuming Leng
Keyword(s):  
Stress State ◽  
Strain Rate ◽  
Dynamic Stress ◽  
Stress Amplitude ◽  
Permanent Deformation ◽  
Confining Pressure ◽  
Coarse Grained ◽  
Deformation Characteristics ◽  
Permanent Strain ◽  
Coarse Grained Soil

AbstractPractical assessment of subgrade settlement induced by train operation requires developing suitable models capable of describing permanent deformation characteristics of subgrade filling under repeated dynamic loading. In this paper, repeated load triaxial tests were performed on coarse-grained soil (CGS), and the axial permanent strain of CGS under different confining pressures and dynamic stress amplitudes was analysed. Permanent deformation behaviors of CGS were categorized based on the variation trend of permanent strain rate with accumulated permanent strain and the shakedown theory. A prediction model of permanent deformation considering stress state and number of load cycles was established, and the ranges of parameters for different types of dynamic behaviors were also divided. The results indicated that the variational trend of permanent strain rate with accumulated permanent strain can be used as a basis for classifying dynamic behaviors of CGS. The stress state (confining pressure and dynamic stress amplitude) has significant effects on the permanent strain rate. The accumulative characteristics of permanent deformation of CGS with the number of load cycles can be described by a power function, and the model parameters can reflect the influence of confining pressure and dynamic stress amplitude. The study’s results could help deepen understanding of the permanent deformation characteristics of CGS.

scholarly journals Plasticity and Deformation Mechanisms of Ultrafine-Grained Ti in Necking Region Revealed by Digital Image Correlation Technique

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 574
Author(s):  
Yonghao Zhao ◽  
Yanglin Gu ◽  
Yazhou Guo
Keyword(s):  
Stress State ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Curve ◽  
Grain Boundary Sliding ◽  
Image Correlation ◽  
Coarse Grained ◽  
Correlation Technique ◽  
Stress Strain ◽  
Ultrafine Grained

The conventional engineering stress-strain curve could not accurately describe the true stress-strain and local deformability of the necking part of tensile specimens, as it calculates the strain by using the whole gauge length, assuming the tensile specimen was deformed uniformly. In this study, we employed 3D optical measuring digital image correlation (DIC) to systematically measure the full strain field and local strain during the whole tensile process, and calculate the real-time strain and actual flow stress in the necking region of ultrafine-grained (UFG) Ti. The post-necking elongation and strain hardening exponent of the UFG Ti necking part were then measured as 36% and 0.101, slightly smaller than those of the coarse grained Ti (52% and 0.167), suggesting the high plastic deformability in the necking part of the UFG Ti. Finite elemental modeling (FEM) indicates that when necking occurs, strain is concentrated in the necking region. The stress state of the necking part was transformed from uniaxial in the uniform elongation stage to a triaxial stress state. A scanning electron microscopic (SEM) study revealed the shear and ductile fracture, as well as numerous micro shear bands in the UFG Ti, which are controlled by cooperative grain boundary sliding. Our work revealed the large plastic deformability of UFG metals in the necking region under a complex stress state.

The Alteration of the Pore Spaces in Sandstones

1973 ◽  
Vol 31 ◽  
pp. 210-211
Author(s):  
R. E. Ferrell ◽  
G. G. Paulson
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
The Other ◽  
Coarse Grained ◽  
Depositional Fabric ◽  
Soluble Components ◽  
Scanning Electron ◽  
Shape And Size

The pore spaces in sandstones are the result of the original depositional fabric and the degree of post-depositional alteration that the rock has experienced. The largest pore volumes are present in coarse-grained, well-sorted materials with high sphericity. The chief mechanisms which alter the shape and size of the pores are precipitation of cementing agents and the dissolution of soluble components. Each process may operate alone or in combination with the other, or there may be several generations of cementation and solution.The scanning electron microscope has ‘been used in this study to reveal the morphology of the pore spaces in a variety of moderate porosity, orthoquartzites.

Sign in / Sign up

Export Citation Format

Share Document