TRIP Effect and Deformation Damaging of Metastable Austenitic Steels

2007 ◽  
Vol 539-543 ◽  
pp. 4903-4908 ◽  
Author(s):  
H. Oettel ◽  
M. Glavatskikh ◽  
U. Martin ◽  
A. Nikulin
Keyword(s):  
Crack Formation ◽  
Uniform Elongation ◽  
Shear Bands ◽  
Local Deformation ◽  
Austenitic Steels ◽  
Low Flow ◽  
Trip Effect ◽  
Fracture Path ◽  
Continuous Transformation ◽  
Additional Hardening

The TRIP – effect in metastable austenitic steels is caused by a moderate local martensitic transformation, connected with an extraordinary increase e.g. of the uniform elongation in tensile testing. In this case the martensite formation causes an additional hardening effect, preventing the local deformation as well as damaging during plastic deformation. The main conditions of a marked TRIP – effect is a low flow stress in the undeformed state, a high strengthening exponent, a continuous transformation up to about 20 % martensite and a high resistance against damaging (e.g. crack formation and propagation). The martensite transformation starts in glide or shear bands and their crossings also at temperatures clearly above the conventional Md – temperatures, reducing the stress local concentrations and so preventing damaging. Furthermore, high martensite contents can be detected along the fracture path, indicating the hindering of the crack propagation by the transformation. To demonstrate the influence of damaging on the TRIP – effect the deviations from the so-called Considere-criterion for uniform elongation can be used. Related to the deformation the damaging under TRIP – conditions is minimal.

scholarly journals Localization of Plastic Deformation in the Copper and Stainless Steels Samples, Irradiated with Neutrons

2022 ◽  
Vol 2155 (1) ◽  
pp. 012009
Author(s):  
Mikhail Merezhko ◽  
Diana Merezhko
Keyword(s):  
Neutron Irradiation ◽  
Stainless Steels ◽  
Materials Science ◽  
Uniform Elongation ◽  
Reactor Core ◽  
Local Deformation ◽  
Austenitic Steels ◽  
Face Centered Cubic ◽  
Term Operation ◽  
Α Phase

Abstract The reduction of ductility of austenitic stainless steels as a result of long-term operation in the nuclear reactor core is an important problem of modern radiation materials science. Understanding the mechanisms of the effect of neutron irradiation on the mechanical properties of austenitic steels is impossible without research of localization processes occurring during the deformation. In this paper, it was found that the value of the true local deformation corresponding to the onset of neck formation in face-centered cubic structured metals decreases with an increase in the radiation dose, while the true stress remains almost constant. Additional hardening of AISI 304 steel due to the intensive formation of the martensitic α’-phase increases not only the stress at which a neck is formed in this alloy, but also the true local deformation. As a result, the uniform elongation increases and remains high after neutron irradiation to 0.05 dpa. The forehanded formation of the martensitic α’-phase in sufficient quantity before the necking onset can be considered as an additional deformation mechanism that will increase the ability of the material to deform uniformly.

scholarly journals Role of Deformation-Induced Martensite in TRIP Effect of Metastable Austenitic Steels

2021 ◽  
Vol 61 (2) ◽  
pp. 556-563
Author(s):  
Noriyuki Tsuchida ◽  
Eiichiro Ishimaru ◽  
Masatomo Kawa
Keyword(s):  
Austenitic Steels ◽  
Trip Effect

Determination of DC06+ZE Sheet Crack Cause

2016 ◽  
Vol 368 ◽  
pp. 121-125
Author(s):  
Pavel Kejzlar ◽  
Tomáš Pilvousek ◽  
Michal Tregler
Keyword(s):  
Stress Concentration ◽  
Tensile Stress ◽  
Deep Drawing ◽  
Crack Formation ◽  
Local Stress ◽  
Local Deformation ◽  
Local Stress Concentration ◽  
Bcc Lattice ◽  
Hard Particles

The present work deals with determination of the cause of crack occurring in a part of car body manufactured from deep-drawing sheet. UHR-SEM, EDS, EBSD and measurement of microhardness were used for evaluation of the structure, local deformation and crack formation mechanism. A material analysis discovered foreign particles in the material. These particles were identified as MgAl2O4 with BCC lattice. The occurrence of these hard particles led to local stress concentration, decrease in mechanical strength and sheet breach due to tensile stress during deformation.

scholarly journals Fine Structure of Shear Bands Formed during Hot Deformation of Two Austenitic Steels

2004 ◽  
Vol 45 (7) ◽  
pp. 2157-2164 ◽  
Author(s):  
Pavel Cizek ◽  
Fang Bai ◽  
W.Mark Rainforth ◽  
John H. Beynon
Keyword(s):  
Fine Structure ◽  
Hot Deformation ◽  
Shear Bands ◽  
Austenitic Steels

Inspection of Adiabatic Shear Bands in High Manganese TRIP Steels

2013 ◽  
Vol 753 ◽  
pp. 72-75 ◽  
Author(s):  
Hui Zhen Wang ◽  
Xiu Rong Sun ◽  
Ping Yang ◽  
Wei Min Mao
Keyword(s):  
Shear Failure ◽  
High Strain ◽  
Shear Bands ◽  
Adiabatic Shear ◽  
Strain Rates ◽  
Trip Effect ◽  
Adiabatic Shear Bands ◽  
High Manganese ◽  
High Strain Rates ◽  
Trip Steels

Adiabatic shear bands (ASBs) develop generally during high strain rates. This paper investigates the transformation induced plasticity (TRIP) effect during ASBs formation at high strain rates in high manganese TRIP steels containing initial austenite and ferrite by EBSD technique. Results show that TRIP effect takes place mainly before the formation of ASBs. After ASBs formation, TRIP effect is strongly restricted by the size effect, the increase of stacking fault energy (SFE) and even inverse martensitic transformation due to the rise of temperature. The TRIP effect before ASBs formation contributes to the resistance of adiabatic shear failure. Dynamic recrystallization driven by subgrains rotation occurs within ASBs, and ultrafine grains often show strong shear textures with twin relationship owing to slip mechanism.

scholarly journals Viscous Shear Banding in Cutting of Metals

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Dinakar Sagapuram ◽  
Koushik Viswanathan
Keyword(s):  
Plastic Flow ◽  
Flow Instability ◽  
Liquid Metals ◽  
Shear Banding ◽  
Shear Bands ◽  
Local Deformation ◽  
Flow Rule ◽  
Sliding Mechanism ◽  
Viscous Shear ◽  
Local Shear

Shear banding is a type of plastic flow instability with often adverse implications for cutting and deformation processing of metals. Here, we study the mechanics of plastic flow evolution within single shear bands in Ti- and Ni-based alloy systems. The local shear band displacement profiles are quantitatively mapped at high resolution using a special micromarker technique. The results show that shear bands, once nucleated, evolve by a universal viscous sliding mechanism that is independent of microstructural details. The evolution of local deformation around the band is accurately captured by a momentum diffusion equation based on a Bingham-type flow rule. The predicted band viscosity is very small, compared to those of liquid metals. A plausible explanation for this small viscosity and fluid-like behavior at the band, based on phonon drag, is presented.

scholarly journals The origin of the boundary strengthening in polycrystal-inspired architected materials

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chen Liu ◽  
Jedsada Lertthanasarn ◽  
Minh-Son Pham
Keyword(s):  
Shear Band ◽  
Mechanical Strength ◽  
Deformation Behaviour ◽  
Shear Bands ◽  
High Strength ◽  
Local Deformation ◽  
Great Capacity ◽  
Boundary Type ◽  
Underlying Mechanisms ◽  
Damage Tolerant

AbstractCrystal-inspired approach is found to be highly successful in designing extraordinarily damage-tolerant architected materials. i.e. meta-crystals, necessitating in-depth fundamental studies to reveal the underlying mechanisms responsible for the strengthening in meta-crystals. Such understanding will enable greater confidence to control not only strength, but also spatial local deformation. In this study, the mechanisms underlying shear band activities were investigated and discussed to provide a solid basis for predicting and controlling the local deformation behaviour in meta-crystals. The boundary strengthening in polycrystal-like meta-crystals was found to relate to the interaction between shear bands and polygrain-like boundaries. More importantly, the boundary type and coherency were found to be influential as they govern the transmission of shear bands across meta-grains boundaries. The obtained insights in this study provide crucial knowledge in developing high strength architected materials with great capacity in controlling and programming the mechanical strength and damage path.

scholarly journals Modelling the Shear Banding in Gradient Nano-Grained Metals

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2468
Author(s):  
Tianyu Chen ◽  
Jianjun Li
Keyword(s):  
Grain Size ◽  
Shear Band ◽  
Uniform Elongation ◽  
Shear Banding ◽  
Shear Bands ◽  
Applied Strain ◽  
Grain Structure ◽  
Coarse Grained ◽  
Gradient Material ◽  
Material Surface

Extensive experiments have shown that gradient nano-grained metals have outstanding synergy of strength and ductility. However, the deformation mechanisms of gradient metals are still not fully understood due to their complicated gradient microstructure. One of the difficulties is the accurate description of the deformation of the nanocrystalline surface layer of the gradient metals. Recent experiments with a closer inspection into the surface morphology of the gradient metals reported that shear bands (strain localization) occur at the surface of the materials even under a very small, applied strain, which is in contrast to previously suggested uniform deformation. Here, a dislocation density-based computational model is developed to investigate the shear band evolution in gradient Cu to overcome the above difficulty and to clarify the above debate. The Voronoi polygon is used to establish the irregular grain structure, which has a gradual increase in grain size from the material surface to the interior. It was found that the shear band occurs at a small applied strain in the surface region of the gradient structure, and multiple shear bands are gradually formed with increasing applied load. The early appearance of shear banding and the formation of abundant shear bands resulted from the constraint of the coarse-grained interior. The number of shear bands and the uniform elongation of the gradient material were positively related, both of which increased with decreasing grain size distribution index and gradient layer thickness or increasing surface grain size. The findings are in good agreement with recent experimental observations in terms of stress-strain responses and shear band evolution. We conclude that the enhanced ductility of gradient metals originated from the gradient deformation-induced stable shear band evolution during tension.

Filtration of Floating Particles by Collectors: Influence of the System Geometry on the Efficiency

2017 ◽  
Author(s):  
Federico Gregori ◽  
Julia Kapran ◽  
Emilie Dressaire
Keyword(s):  
Fluid Flow ◽  
Numerical Study ◽  
Local Deformation ◽  
Trapping Efficiency ◽  
Low Flow ◽  
Maximum Efficiency ◽  
Capillary Length ◽  
Capillary Interactions ◽  
Capillary Attraction ◽  
Floating Particles

Important industrial processes including oil extraction, mineral processing and wastewater treatment, rely on the separation of buoyant particles from a liquid phase. The capillary attraction between floating particles and fixed collectors can be leveraged to improve the efficiency of the separation process. The capture of an advected floating particle by a fixed cylindrical obstacle is due to direct interception and capillary attraction for sub-millimeter particles. The capillary attraction stems from the local deformation of the air/liquid interface. Previous work has established that floating particles placed on the surface of a still liquid bath, spontaneously move toward or away from one another depending on their surface properties. More recently, a numerical study has considered the competition between hydrodynamic and capillary interactions as floating particles are advected past a fixed cylinder. This seminal work revealed that capillary interactions can enhance the capture of particles at low flow velocity. Building on these results, we develop a numerical approach to study the interactions between advected particles and an array of obstacles. The results are obtained with the finite element modeling of the fluid flow in the channel, in presence of obstacles. Assuming that the particles do not alter the fluid flow, we solve the momentum conservation equation for each advected particle using the Basset Boussineq Oseen equation. If contact occurs, we assume that the particle is captured by the obstacle, thus neglecting inertial effects. We demonstrate that an array of obstacles can capture most of the particles traveling down the channel. First, we show that the efficiency of an array of obstacles, i.e. the fraction of particles captured depends on interfacial and hydrodynamic effects. For example, parameters such as the Reynolds number, capillary length, contact angle and collector size influence the trapping efficiency. Second we vary the geometry of the array and seek to minimize the amount of static material needed to get the maximum efficiency. These results provide guidelines for the design of efficient filters.

Sign in / Sign up

Export Citation Format

Share Document