Neutron Diffraction Measurements of Deformation and Recrystallization Textures in Cold Wire-Drawn Copper

The crystallographic texture of electrolytic tough pitch copper has been investigated by neutron diffraction after deformation by cold wire-drawing (reduction of area between 51 and 94 %) and after static recrystallization. The deformation texture characterized by a strong <111> fiber is reinforced with increasing strain, while the volume fraction of <100> fiber is reduced. In turn, we show that the <100> fiber is strongly reinforced after recrystallization when intensity of the <100> maxima increases with the level of deformation. Since the <111> fiber disappears first during annealing, the static recrystallization has been followed “in situ” by measurements of the diffracted intensity evolution in the center of the {111} pole figure. From these experimental data and taking into account the Arrhenius equation, the activation energy of the recrystallization process has been determined for each deformation rate.

Download Full-text

Deformation Behaviour of TRIP Steel Monitored by In Situ Neutron Diffraction

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.939.25 ◽

2014 ◽

Vol 939 ◽

pp. 25-30

Author(s):

Jozef Zrník ◽

Ondrej Muránsky ◽

Petr Sittner

Keyword(s):

Neutron Diffraction ◽

Trip Steel ◽

Retained Austenite ◽

Volume Fraction ◽

Tensile Deformation ◽

Deformation Behaviour ◽

Tensile Load ◽

Ferrite Matrix ◽

Granular Bainite

The paper presents results ofin-situneutron diffraction experiments aimed on monitoring the phase evolution and load distribution in transformation induced plasticity (TRIP) steel when subjected to tensile loading. Tensile deformation behaviour of two TRIP-assisted multiphase steel with slightly different microstructures resulted from different thermo-mechanical treatments applied was investigated byin-situneutron diffraction. The steel with lower retained austenite volume fraction (fγ=0.04) and higher volume fraction of needle-like bainite in the α-matrix exhibits higher yield stress (sample B, 600MPa) but considerably lower elongation in comparison to the steel with higher austenite volume fraction (fγ=0.08), granular bainite and ferrite matrix (sample A, 500 MPa). The neutron diffraction results showed that the applied tensile load is redistributed at the yielding point in a way that the retained austenite bears a significantly larger load than the α-matrix during the TRIP steel deformation. Steel sample with higher volume fraction of retained austenite and less strong ferrite matrix proved to be a better TRIP steel with respect to strength, ductility and the side effect of the strain induced austenite-martensite transformation. The transforming retained austenite in time of loading provides potential for higher ductility of experimental TRIP steel but at the same time acts as a reinforcement phase during the further plastic deformation.TRIP steel, austenite conditioning, austenite transformation, structure, retained austenite, tensile deformation, neutron diffraction, load partitioning, mechanical properties.

Download Full-text

In Situ Neutron Diffraction during Thermo-Mechanically Controlled Process in Low Alloy Steels

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.118.419 ◽

2006 ◽

Vol 118 ◽

pp. 419-424

Author(s):

M.S. Koo ◽

Ping Guang Xu ◽

J.H. Li ◽

Yo Tomota ◽

O. Muransky ◽

...

Keyword(s):

Neutron Diffraction ◽

Volume Fraction ◽

Structural Evolution ◽

Low Alloy Steels ◽

Controlled Processing ◽

Ferrite Transformation ◽

Alloy Steels ◽

Time Division ◽

In Situ Neutron Diffraction

A challenge was made to examine the micro-structural evolution during thermomechanically controlled processing (TMCP) by in situ neutron diffraction. Since the neutron beam is too weak to achieve a time-division measurement to follow a rapid transformation in alow carbon steel, 2%Mn was added to make the austenite to ferrite transformation slower. Round bar specimens were heated up to 900°C with an electrical resistance method, then cooled down to 700°C, and compressed by 25% followed by step-by-step cooling. During the step-by-step cooling, neutron diffraction profiles were obtained and the volume fraction of ferrite, phase stresses and FWHM were analyzed. Using a similar TMCP simulator, specimens were quenched into water at several stages of the heat schedule to freeze the corresponding microstructures, which were observed with OM and SEM. As results, the ferrite volume fraction determined by neutron diffraction on cooling agrees well with that by microscopy. It is found that the austenite deformation and/or Nb addition accelerate the ferrite transformation to result in finer grain size.

Download Full-text

Study on Hot Deformation Behavior of 97# High Strength Rod

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.159.322 ◽

2012 ◽

Vol 159 ◽

pp. 322-325

Author(s):

Hong Bin Li ◽

Fang Fang

Keyword(s):

Hot Deformation ◽

Deformation Behavior ◽

Static Recrystallization ◽

Volume Fraction ◽

High Strength ◽

Avrami Equation ◽

Recrystallization Process ◽

Hot Deformation Behavior ◽

Deformation Behaviors ◽

Gleeble 3500

the hot deformation behaviors of 97# High Strength Rod was investigated through double-hit compression experiments using Gleeble 3500 thermal-mechanical similar within the temperature range of 850~1100°C, the strain rate of 5 s-1 and the interval range of 1-100s, the softening fractiong at different pass interval and deforming temperature was determined and analyzed. The results show that when pass intervals is the same, as deformation temperature increase, the volume fraction of static recrystallization of 97# High Strength Rod increases and the recrystallization process is enchanced. Activation energy of austenite static recrystallization of 97# High Strength Rod is 100.476 kJ/mol. The kinetic equation of static recrystallization of 97# High Strength Rod by avrami equation wan obtained.

Download Full-text

In Situ Neutron Diffraction Analysis of Phase Transformation Kinetics in TRIP Steel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.502.339 ◽

2005 ◽

Vol 502 ◽

pp. 339-344 ◽

Cited By ~ 7

Author(s):

Jozef Zrník ◽

O. Muránsky ◽

Petr Lukáš ◽

Petr Šittner ◽

Z. Nový

Keyword(s):

Neutron Diffraction ◽

Trip Steel ◽

Retained Austenite ◽

Volume Fraction ◽

Internal Stresses ◽

Austenite Transformation ◽

Austenite Stability ◽

Retained Austenite Stability ◽

In Situ Neutron Diffraction

The precise characterization of the multiphase microstructure of low alloyed TRIP steels is of great importance for the interpretation and optimisation of their mechanical properties. In-situ neutron diffraction experiment was employed for monitoring of conditioned austenite transformation to ferrite, and also for retained austenite stability evaluation during subsequent mechanical loading. The progress in austenite decomposition to ferrite is monitored at different transformation temperatures. The relevant information on the course of transformation is extracted from neutron diffraction spectra. The integrated intensities of austenite and ferrite neutron diffraction profiles over the time of transformation are then assumed as a measure of the volume fractions of both phases in dependence on transformation temperature. Useful information was also obtained on retained austenite stability in TRIP steel during mechanical testing. The in-situ neutron diffraction experiments were conducted at two different diffractometers to assess the reliability of neutron diffraction technique in monitoring the transformation of retained austenite during room temperature tensile test. In both experiments the neutron investigation was focused on the volume fraction quantification of retained austenite as well as on internal stresses rising in structure phases due to retained austenite transformation.

Download Full-text

Deformation Behaviour of TRIP Steel Monitoring by in-Situ Neutron Diffraction

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.465.390 ◽

2011 ◽

Vol 465 ◽

pp. 390-394 ◽

Cited By ~ 1

Author(s):

Jozef Zrník ◽

Ondrej Muránsky ◽

Petr Šittner ◽

E.C. Oliver

Keyword(s):

Neutron Diffraction ◽

Trip Steel ◽

Retained Austenite ◽

Volume Fraction ◽

Tensile Deformation ◽

Deformation Behaviour ◽

Tensile Load ◽

Phase Evolution ◽

In Situ Neutron Diffraction

The paper presents results of in-situ neutron diffraction experiments aimed on monitoring the phase evolution and load distribution in TRIP steel when subjected to tensile loading. Tensile deformation behaviour of TRIP steel with different initial microstructures showed that the applied tensile load is redistributed at the yield point and the harder retained austenite (Feγ) bears larger load then ferrite (Feα) matrix. After load partioning is finished, macroscopic yielding comes through simultaneous activity of the martensite transformation (in the austenite) and plastic deformation process in ferrite. The steel with higher volume fraction of retained austenite and less stronger ferrite appears to be a better TRIP steel having efficient structure for better plasticity purpose.

Download Full-text

Neutron Diffraction Analysis of Load Transfer in DP 600 Steel During In Situ Tensile Tests

Materials Science Forum ◽

10.4028/www.scientific.net/msf.681.31 ◽

2011 ◽

Vol 681 ◽

pp. 31-36

Author(s):

Marc Seefeldt ◽

Steven Dillien ◽

Uwe Stuhr

Keyword(s):

Neutron Diffraction ◽

Inflection Point ◽

Load Transfer ◽

Volume Fraction ◽

Tensile Tests ◽

Martensite Phase ◽

Lattice Plane ◽

Hard Phase ◽

Plastic Part

The load transfer among ferrite orientations and between ferrite and martensite was analysed in DP 600 steel by means of neutron diffraction duringin situtensile tests on the multiple pulse overlap time-of-flight strain scanner POLDI. The material had 0.07 wt% C and a martensite volume fraction of 15%.In situtests were done in “Young” as well as in “Poisson setup”. The martensite phase could not be probed due to its low tetragonality. The curves of the lattice plane strains as a function of the externally applied macroscopic stress reveal (1) plastic relaxations of transformation and intergranular stresses in the compliant <100> oriented grains, and (2) a second inflection point in the fully plastic part indicating the onset of plastic deformation of the hard phase.

Download Full-text

Investigating the Difference in Mechanical Stability of Retained Austenite in Bainitic and Martensitic High-Carbon Bearing Steels using in situ Neutron Diffraction and Crystal Plasticity Modeling

Metals ◽

10.3390/met9050482 ◽

2019 ◽

Vol 9 (5) ◽

pp. 482 ◽

Cited By ~ 2

Author(s):

Rohit Voothaluru ◽

Vikram Bedekar ◽

Dunji Yu ◽

Qingge Xie ◽

Ke An ◽

...

Keyword(s):

Neutron Diffraction ◽

Crystal Plasticity ◽

Retained Austenite ◽

Mechanical Stability ◽

Volume Fraction ◽

High Carbon ◽

Martensitic Matrix ◽

Bearing Steels ◽

In Situ Neutron Diffraction

In situ neutron diffraction of the uniaxial tension test was used to study the effect of the surrounding matrix microstructure on the mechanical stability of retained austenite in high-carbon bearing steels. Comparing the samples with bainitic microstructures to those with martensitic ones, it was found that the retained austenite in a bainitic matrix starts transforming into martensite at a lower strain compared to that within a martensitic matrix. On the other hand, the rate of transformation of the austenite was found to be higher within a martensitic microstructure. Crystal plasticity modeling was used to analyze the transformation phenomenon in these two microstructures and determine the effect of the surrounding microstructure on elastic, plastic, and transformation components of the strain. The results showed that the predominant difference in the deformation accumulated was from the transformation strain and the critical transformation driving force within the two microstructures. The retained austenite was more stable for identical loading conditions in case of martensitic matrix compared to the bainitic one. It was also observed that the initial volume fraction of retained austenite within the bainitic matrix would alter the onset of transformation to martensite, but not the rate of transformation.

Download Full-text

MULTILEVEL PHYSICAL-ORIENTED MODEL: APPLICATION TO THE DESCRIPTION OF THE INITIAL STAGE OF DYNAMIC RECRYSTALLIZATION OF POLYCRYSTALS

Problems of Strength and Plasticity ◽

10.32326/1814-9146-2021-83-4-451-461 ◽

2021 ◽

Vol 83 (4) ◽

pp. 451-461

Author(s):

N.S. Kondratev ◽

P.V. Trusov ◽

A.N. Podsedertsev

Keyword(s):

High Temperature ◽

Dynamic Recrystallization ◽

Volume Fraction ◽

Deformation Texture ◽

High Temperature Deformation ◽

Temperature Deformation ◽

Material Structure ◽

Recrystallization Process ◽

Preliminary Deformation ◽

Deformation Trajectory

Thermomechanical processing of metals and alloys is accompanied by deep changes of the material structure (including grain structure), which determines physical and mechanical properties and the working characteristics of products made from them. Its change is possible due to mechanical (fragmentation process) and/or temperature (recrystallization process) influences. Because of this, an urgent task is to create mathematical models that allow describing changes in the material structure and the stress-strain state under thermomechanical treatment. For this purpose, the multilevel physically oriented model was developed for researching inelastic deformation of polycrystals. The problem of modeling two stages deformation of a polycrystalline copper sample was formulated. At the first stage, preliminary cold intense plastic deformation under complex loading was investigated. Two variants of preliminary deformation were considered. They were homogeneous deformation corresponding to equal-channel angular compression (ECUP), and deformation with closed deformation trajectory. At the second stage, uniaxial high-temperature deformation was considered prior to the beginning of an intensive dynamic recrystallization. The paper describes the method for estimating the recrystallized material volume fraction within the framework of the multilevel model. The influence of the deformation temperature, the preliminary deformation, the deformation texture, and the average angle of mutual misorientation of neighboring grains on recrystallization was investigated. These parameters determine the development of dynamic recrystallization, since its main physical cause is the difference in stored energy between neighboring grains. It was shown that the developed mathematical model is suitable for describing the thermal activation of dynamic recrystallization at temperatures in the range of 0,4–0,7 homologous temperature. The deformation trajectory complexity determines the type of deformation texture, its “sharpness” or “dispersion”, the angles of neighboring grains mutual misorientation. The results of computational experiments are presented. According to the proposed method, the deformation at the high-temperature stage is determined, at which the intensive migration of new grains begins during recrystallization.

Download Full-text

Distinct Recrystallization Pathways in a Cold-Rolled Al-2%Mg Alloy Evidenced by In-Situ Neutron Diffraction

Quantum Beam Science ◽

10.3390/qubs2030017 ◽

2018 ◽

Vol 2 (3) ◽

pp. 17 ◽

Cited By ~ 2

Author(s):

Grigoreta Stoica ◽

Luc Dessieux ◽

Alexandru Stoica ◽

Sven Vogel ◽

Govindarajan Muralidharan ◽

...

Keyword(s):

Neutron Diffraction ◽

Texture Evolution ◽

Deformation Texture ◽

Mg Alloy ◽

Scanning Calorimetry ◽

Los Alamos ◽

Oak Ridge ◽

Quasi Monte Carlo ◽

Cold Rolled

The time-of-flight neutron diffraction data collected in-situ on Oak Ridge National Laboratory’s (ORNL, Oak Ridge, TN, USA) VULCAN and Los Alamos National Laboratory’s (LANL, Los Alamos, NM, USA) High-Pressure-Preferred-Orientation (HIPPO) diffractometers have been analyzed complementarily to show the texture evolution during annealing of a cold-rolled Al-2%Mg alloy. The texture analysis aimed to identify the components present in the initial rolling (or deformation) texture and in the thermally-activated recrystallization texture, respectively. Using a quasi-Monte-Carlo (QMC) approach, a new method has been developed to simulate the weighted texture components, and to obtain inverse pole figures for both rolling and normal directions. As such, distinct recrystallization pathways during annealing in isochronal conditions, can be revealed in terms of the evolution of the texture components and their respective volume fractions. Moreover, the recrystallization kinetics associated with the cube and random texture components are analyzed quantitatively using a similar approach developed for differential scanning calorimetry (DSC).

Download Full-text