Plastic Deformation and Fracture Initiation Typology Analysis under a Triaxial Tensile State of Stress Using the Quantitative Assessment of Microstructural Changes

2012 ◽  
Vol 267 ◽  
pp. 17-24
Author(s):  
Voicu Ioan Safta ◽  
Voicu Ionel Safta
Keyword(s):  
Plastic Deformation ◽  
Axial Stress ◽  
Fracture Initiation ◽  
Deformation Degree ◽  
Stress Concentrators ◽  
State Of Stress ◽  
Deformation And Fracture ◽  
Specimen Axis ◽  
Geometric Changes ◽  
Typology Analysis

The paper approaches the influence problems, due to increase in plastic deformation and fracture initiation, upon the multi-axial stress state. The experiments are based on determining the geometric changes of stress concentrators and the increase of granulation anisotropy of unalloyed steel related to the plastic deformation. In order to evince the changes in the concentrators shape, at high levels of deformation, an average parameter of shape was introduced. The 3D Complex representations, based on measurements have indicated the dependence of longitudinal specific deformations for the deformation degree, as well as sectional position in the area under measurement. The variation functions of the longitudinal specific deformation of the medium average shape parameter showed an opposed linear dependence at the top of the tension concentrator relatively to the tested specimen axis. Taking into consideration the average parameter of shape, the experimental correlations were more conclusive. Evaluating the microstructural state of stress concentrators, the deformations have revealed distinct fracture typologies, influenced by the specific state of deformation. By synthesizing the information regarding the fracture initiation, an typological diagram of fracture initiation TDI was elaborated. In this diagram, representing the cross section of the specimens, for different values of the stress concentrator factor, six quasi-quantitative zones have been analyzed.

scholarly journals Experiments on Rocks Under High Pressure Conditions in GTA 20-32 Triaxial Press / Experimenty Na Horninách Ve Vysokotlakém Triaxiálním Lisu GTA 20-32

2012 ◽  
Vol 58 (1) ◽  
pp. 9-16
Author(s):  
Josef Poláček ◽  
Alena Kožušníková
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Brittle Failure ◽  
Axial Stress ◽  
Deformation Behaviour ◽  
Confining Pressure ◽  
Strength Properties ◽  
Experimental Results ◽  
State Of Stress ◽  
Different Types

Abstract The paper describes the methodology of measurements in the GTA 20-32 triaxial press. The deformation behaviour of two different types of rocks was compared: - gypsum with plastic deformation even at lower confining pressure, - Carboniferous sandstone with brittle failure even at the highest confining pressure. The influence of gypsum layering was studied as well. The experimental results show that the deformation and strength properties of the gypsum in the triaxial state of stress do not significantly depend on the orientation of axial stress to the observed layering.

Plastic deformation and fracture of polycrystalline Ni–Ti with stress concentrators of different scales

1998 ◽  
Vol 30 (1) ◽  
pp. 19-26 ◽  
Author(s):  
V.E Panin ◽  
Ye.Ye Deryugin ◽  
L.S Derevyagina ◽  
A.I Lotkov ◽  
B.I Suvorov
Keyword(s):  
Plastic Deformation ◽  
Stress Concentrators ◽  
Deformation And Fracture

In-situ EBSD study of the degradation behavior in a type 316 Austenitic Stainless Steel during plastic deformation

2021 ◽  
pp. 030932472098493
Author(s):  
Xiao Wang ◽  
Yuetao Zhang ◽  
Huaying Li ◽  
Ming-yu Huang
Keyword(s):  
Plastic Deformation ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Tensile Deformation ◽  
Target Surface ◽  
Local Orientation ◽  
Deformation Degree ◽  
Band Contrast

Type 316 steels have been heavily utilized as the structural material in many construction equipment and infrastructures. This paper reports the characterization of degradation in 316 austenitic stainless steel during the plastic deformation. The in-situ EBSD results revealed that, with the increase of plastic strain, the band contrast (BC) value progressively decreased in both grain and grain boundaries, and the target surface becomes uneven after the plastic tensile, which indicates that the increase of surface roughness. Meanwhile, the KAM and ρGND values are low in the origin specimen but increased significantly after the in-situ tensile. The results indicated that the KAM and ρGND are closely related to the deformation degree of the materials, which can be used as the indicator for assessing the degradation of 316 steel. Besides, the re-orientation of grain occurred after the tensile deformation, which can be recognized from the lattice orientation and local orientation maps.

The effect of phase transformations in the process of electrom-beam 3D-printing and post-built heat treatment on the peculiarities of plastic deformation and fracture of high nitrogen Cr-Mn steel

2021 ◽  
pp. 10-17
Author(s):  
E.G. Astafurova ◽  
◽  
K.A. Reunova ◽  
S.V. Astafurov ◽  
M.Yu. Panchenko ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Plastic Deformation ◽  
Electron Beam ◽  
Phase Composition ◽  
Additive Manufacturing ◽  
3D Printing ◽  
Raw Material ◽  
High Nitrogen ◽  
Two Phase ◽  
Deformation And Fracture

We investigated the phase composition, plastic deformation and fracture micromechanisms of Fe-(25-26)Cr-(5-12)Mn-0.15C-0.55N (wt. %) high-nitrogen chromium-manganese steel. Obtained by the method of electron-beam 3D-printing (additive manufacturing) and subjected to a heat treatment (at a temperature of 1150°C following by quenching). To establish the effect of the electron-beam 3D-printing process on the phase composition, microstructure and mechanical properties of high-nitrogen steel, a comparison was made with the data for Fe-21Cr-22Mn-0.15C-0.53N austenitic steel (wt. %) obtained by traditional methods (casting and heat treatment) and used as a raw material for additive manufacturing. It was experimentally established that in the specimens obtained by additive manufacturing method, depletion of the steel composition by manganese in the electron-beam 3D-printing and post-built heat treatment contributes to the formation of a macroscopically and microscopically inhomogeneous two-phase structure. In the steel specimens, macroscopic regions of irregular shape with large ferrite grains or a two-phase austenite-ferrite structure (microscopic inhomogeneity) were observed. Despite the change in the concentration of the basic elements (chromium and manganese) in additive manufacturing, a high concentration of interstitial atoms (nitrogen and carbon) remains in steel. This contributes to the macroscopically heterogeneous distribution of interstitial atoms in the specimens - the formation of a supersaturated interstitial solid solution in the austenitic regions due to the low solubility of nitrogen and carbon in the ferrite regions. This inhomogeneous heterophase (ferrite-austenite) structure has high strength properties, good ductility and work hardening, which are close to those of the specimens of the initial high-nitrogen austenitic steel used as the raw material for additive manufacturing.

Experimental and numerical investigation of Armox 500T armor steel perforation process

2021 ◽  
Vol 70 (1) ◽  
pp. 43-61
Author(s):  
Arkadiusz Popławski
Keyword(s):  
Plastic Deformation ◽  
Strain State ◽  
Numerical Study ◽  
Stress And Strain ◽  
Failure Model ◽  
Modes Of Failure ◽  
State Of Stress ◽  
Computational Code ◽  
Armor Steel ◽  
Plate Perforation

This paper presents the results of an experimental and numerical study of the perforation of Armox 500T armoured steel. The plate perforation was performed with a pneumatic gun using three types of penetrators. Sharp, spherical and blunt penetrators were used. The use of different geometries of penetrators causes the process of perforation and destruction of plates in a different state of stress and strain, which leads to the appearance of three basic modes of failure. Numerical analyses of the perforation process have been carried out using the Ls-Dyna computational code with an advanced constitutive model of the material and the integrated failure model. The obtained experimental and numerical results were analysed and compared. The failure shape, the level of plastic deformation and the parameters of stress and strain state were analysed.

Electronic Excitation during Plastic Deformation and Fracture of Crystals

1991 ◽  
Vol 195 (1-2) ◽  
pp. 153-153
Author(s):  
U. Messerschmidt
Keyword(s):  
Plastic Deformation ◽  
Electronic Excitation ◽  
Deformation And Fracture
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