Special Issue "Deformation-Induced Phase Transformations in Steels and Non-Ferrous Alloys"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (30 April 2018)

Special Issue Editors

Guest Editor
Prof. Elena Pereloma

Professor of Physical Metallurgy, Director of UOW Electron Microscopy Centre, AIIM, Squires Way, Innovation Campus, University of Wollongong, North Wollongong, NSW 2500, Australia NSW 2500, Australia
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Interests: physical metallurgy; steels; phase transformations; Ti alloys; atom probe tomography; mechanical behaviour; recrystallization
Guest Editor
Dr. Ilana Timokhina

Institute for Frontier Materials, Deakin University, Geelong, VIC 3217, Australia
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Interests: physical metallurgy; thermo-mechanical processing; atom probe tomography; clustering; phase transformations; electron microscopy; strengthening mechanisms

Special Issue Information

Dear Colleagues,

Deformation-induced phase transformations commonly occur during processing or in-service of parts made from steels or non-ferrous alloys. Examples include, but are not limited to, deformation-induced ferrite formation in steels, transformations of austenite to ε or α martensite in steels, transformations of β phase in metastable Ti alloys to α’’ martensite or ω phase; transformation of ZrCu (B2) austenite to ZrCu martensite in ZrCu-based alloys; stress-induced hcp martensite formation in Co-based alloys from parent fcc phase; and cubic B2 → monoclinic B19' martensitic transformation in NiTi alloys. Such transformations may have a remarkable effect on work hardening behaviour and plasticity of materials.

Papers on recent advances in theoretical and experimental investigations and review papers on the effect of parent phase (phase stability, composition, grain size, morphology, texture) and external (strain, strain rate, deformation path, temperature) conditions on deformation-induced phase transformations and the resulting mechanical properties of materials are thought after for inclusion in this Special Issue.

Prof. Elena Pereloma
Dr. Ilana Timokhina
Guest Editors

Manuscript Submission Information

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Keywords

  • Deformation-induced phase transformation
  • Stress
  • Strain
  • Deformation path
  • Phase stability
  • Transformation-induced plasticity
  • Microstructure characterisation
  • Modelling

Published Papers (9 papers)

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Research

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Open AccessArticle Determination of the Critical Stress Associated with Dynamic Phase Transformation in Steels by Means of Free Energy Method
Metals 2018, 8(5), 360; https://doi.org/10.3390/met8050360
Received: 30 April 2018 / Revised: 11 May 2018 / Accepted: 14 May 2018 / Published: 16 May 2018
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Abstract
The double differentiation method overestimates the critical stress associated with the initiation of dynamic transformation (DT) because significant amounts of the dynamic phase must be present in order for its effect on the work hardening rate to be detectable. In this work, an
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The double differentiation method overestimates the critical stress associated with the initiation of dynamic transformation (DT) because significant amounts of the dynamic phase must be present in order for its effect on the work hardening rate to be detectable. In this work, an alternative method (referred to here as the free energy method) is presented based on the thermodynamic condition that the driving force is equal to the total energy obstacle during the exact moment of transformation. The driving force is defined as the difference between the DT critical stress (measured in the single-phase austenite region) and the yield stress of the fresh ferrite that takes its place. On the other hand, the energy obstacle consists of the free energy difference between austenite and ferrite, and the work of shear accommodation and dilatation associated with the phase transformation. Here, the DT critical stresses in a C-Mn steel were calculated using the free energy method at temperatures ranging from 870 °C to 1070 °C. The results show that the calculated critical stress using the present approach appears to be more accurate than the values measured by the double differentiation method. Full article
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Open AccessArticle Influence of Intercritical Annealing Temperature on Microstructure and Mechanical Properties of a Cold-Rolled Medium-Mn Steel
Metals 2018, 8(5), 357; https://doi.org/10.3390/met8050357
Received: 27 April 2018 / Revised: 11 May 2018 / Accepted: 14 May 2018 / Published: 15 May 2018
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Abstract
Medium-Mn steels are characterized by ultrafine-grained (UFG) duplex microstructure consisting of ferrite and a large amount of retained austenite. Intercritical annealing is of great importance to achieving the UFG duplex microstructure and adjusting amount as well as stability of retained austenite. In the
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Medium-Mn steels are characterized by ultrafine-grained (UFG) duplex microstructure consisting of ferrite and a large amount of retained austenite. Intercritical annealing is of great importance to achieving the UFG duplex microstructure and adjusting amount as well as stability of retained austenite. In the present work, the influence of intercritical annealing temperature on the microstructure and mechanical properties was investigated in a cold-rolled medium-Mn steel Fe-12Mn-3Al-0.05C. Particularly, the dependence of microstructural morphology on intercritical annealing temperature was emphasized to reveal the genesis of the microstructural morphology in medium-Mn steels. The ferrite-austenite duplex microstructure manifested an elongated morphology in the specimen annealed at 555 °C, which inherited the lath structure of the cold-rolled state. The medium-Mn steel exhibited a continuous yielding behavior and a relatively low strain-hardening rate. With an increase in intercritical annealing temperature up to 650 °C, the amount of retained austenite increased and microstructure was partially recrystallized, showing a mixture of elongated and equiaxed grain morphologies. When the intercritical annealing was applied at 700 °C, the medium-Mn steel mainly exhibited recrystallized microstructure with equiaxed morphology. The optimal balance between the amount and the stability of retained austenite led to an enhancement of strain hardening and ductility. With a further increase in the intercritical annealing temperature to 750 °C, the medium-Mn steel possessed pronounced strain-hardening behavior at the beginning of the tensile deformation with deteriorated ductility. Full article
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Open AccessArticle Local Deformation and Mn-C Short-Range Ordering in a High-Mn Fe-18Mn-0.6C Steel
Metals 2018, 8(5), 292; https://doi.org/10.3390/met8050292
Received: 26 March 2018 / Revised: 13 April 2018 / Accepted: 16 April 2018 / Published: 24 April 2018
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Abstract
The localized deformation in the high-Mn austenitic Fe-18Mn-0.6C (wt %) steel manifests itself as serrations in the stress–strain curves and Portevin–Le Chatelier (PLC) bands characterized by digital image correlation (DIC) analysis in uniaxial tensile tests. The serrated flow is correlated with the nucleation,
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The localized deformation in the high-Mn austenitic Fe-18Mn-0.6C (wt %) steel manifests itself as serrations in the stress–strain curves and Portevin–Le Chatelier (PLC) bands characterized by digital image correlation (DIC) analysis in uniaxial tensile tests. The serrated flow is correlated with the nucleation, propagation and dying away of PLC bands. The PLC band velocity decreases with increasing strain. In this present study, the Mn-C short-range ordering (SRO) was analyzed quantitatively using small angle neutron scattering (SANS) in Fe-18Mn-0.6C steel. The size and number density of the Mn-C SRO were determined as a function of engineering strain at room temperature. The mean radius of the Mn-C SRO decreases, while the number density increases when there is an increase in the engineering strain. The influence of PLC bands on Mn-C SRO in tensile tests was further discussed. Full article
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Open AccessArticle Correlation between Fatigue Crack Growth Behavior and Fracture Surface Roughness on Cold-Rolled Austenitic Stainless Steels in Gaseous Hydrogen
Metals 2018, 8(4), 221; https://doi.org/10.3390/met8040221
Received: 6 March 2018 / Revised: 26 March 2018 / Accepted: 26 March 2018 / Published: 28 March 2018
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Abstract
Austenitic stainless steels are often considered candidate materials for use in hydrogen-containing environments because of their low hydrogen embrittlement susceptibility. In this study, the fatigue crack growth behavior of the solution-annealed and cold-rolled 301, 304L, and 310S austenitic stainless steels was characterized in
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Austenitic stainless steels are often considered candidate materials for use in hydrogen-containing environments because of their low hydrogen embrittlement susceptibility. In this study, the fatigue crack growth behavior of the solution-annealed and cold-rolled 301, 304L, and 310S austenitic stainless steels was characterized in 0.2 MPa gaseous hydrogen to evaluate the hydrogen-assisted fatigue crack growth and correlate the fatigue crack growth rates with the fracture feature or fracture surface roughness. Regardless of the testing conditions, higher fracture surface roughness could be obtained in a higher stress intensity factor (∆K) range and for the counterpart cold-rolled specimen in hydrogen. The accelerated fatigue crack growth of 301 and 304L in hydrogen was accompanied by high fracture surface roughness and was associated with strain-induced martensitic transformation in the plastic zone ahead of the fatigue crack tip. Full article
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Open AccessFeature PaperArticle Formation of Deformation-Induced Products in a Metastable-β Titanium Alloy during High Temperature Compression
Metals 2018, 8(2), 100; https://doi.org/10.3390/met8020100
Received: 22 December 2017 / Revised: 22 January 2018 / Accepted: 25 January 2018 / Published: 30 January 2018
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Abstract
A metastable-β titanium alloy, Ti-10V-3Fe-3Al (wt. %), was subjected to thermo-mechanical processing including the compression test at 725 °C, which is below the β transus temperature (780 °C), and at strain rate of 10−3 s−1. The presence of phases was
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A metastable-β titanium alloy, Ti-10V-3Fe-3Al (wt. %), was subjected to thermo-mechanical processing including the compression test at 725 °C, which is below the β transus temperature (780 °C), and at strain rate of 10−3 s−1. The presence of phases was determined using transmission electron microscopy and X-ray diffraction. Although the dynamic recovery took place together with slip, both deformation-induced α” martensite and ω were detected as other operating mechanisms for the first time in metastable-β titanium alloy deformed in α + β region. The volume fraction of stress-induced α” was higher than that of the same alloy deformed at room temperature due to a higher strain applied. Stress-induced twinning was not operational, which could be related to the priority of slip mechanism at high temperature resulted from thermally-assisted nucleation and lateral migration of kink-pairs. Full article
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Open AccessArticle The α → ω Transformation in Titanium-Cobalt Alloys under High-Pressure Torsion
Received: 10 November 2017 / Revised: 10 December 2017 / Accepted: 18 December 2017 / Published: 21 December 2017
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Abstract
The pressure influence on the α → ω transformation in Ti–Co alloys has been studied during high pressure torsion (HPT). The α → ω allotropic transformation takes place at high pressures in titanium, zirconium and hafnium as well as in their alloys. The
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The pressure influence on the α → ω transformation in Ti–Co alloys has been studied during high pressure torsion (HPT). The α → ω allotropic transformation takes place at high pressures in titanium, zirconium and hafnium as well as in their alloys. The transition pressure, the ability of high pressure ω-phase to retain after pressure release, and the pressure interval where α and ω phases coexist depend on the conditions of high-pressure treatment. During HPT in Bridgeman anvils, the high pressure is combined with shear strain. The presence of shear strain as well as Co addition to Ti decreases the onset of the α → ω transition from 10.5 GPa (under quasi-hydrostatic conditions) to about 3.5 GPa. The portion of ω-phase after HPT at 7 GPa increases in the following sequence: pure Ti → Ti–2 wt % Co → Ti–4 wt % Co → Ti–4 wt % Fe. Full article
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Open AccessArticle Effect of Nitrogen on Deformation-Induced Martensitic Transformation in an Austenitic 301 Stainless Steels
Metals 2017, 7(11), 503; https://doi.org/10.3390/met7110503
Received: 15 October 2017 / Revised: 7 November 2017 / Accepted: 10 November 2017 / Published: 13 November 2017
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Abstract
The effect of nitrogen on deformation-induced martensitic transformation (DIMT) in metastable 301 austenitic stainless steel has been studied based on the inelastic deformation theory. DIMT is regarded here as continuous relaxation process of internal strain energy accumulated during inelastic deformation. Using the kinetics
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The effect of nitrogen on deformation-induced martensitic transformation (DIMT) in metastable 301 austenitic stainless steel has been studied based on the inelastic deformation theory. DIMT is regarded here as continuous relaxation process of internal strain energy accumulated during inelastic deformation. Using the kinetics equation based on the inelastic deformation theory the relationship between the volume fraction of transformed martensite and inelastic strain for DIMT has been successfully verified with the parameter representing the stability of austenite. The addition of nitrogen is experimentally found to increase austenite stability and the critical inelastic strain below which any DIMT is not observed to occur and to decrease the saturation volume fraction of α’ martensite. On the other hand, DIMT has been analyzed with its effect on stress-strain curve shape and mechanical properties in relation to the addition of nitrogen. The characteristic transition from sigmoidal to parabolic curve shape in stress-strain response has disappeared with the addition of nitrogen. Full article
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Review

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Open AccessReview A Review of Metastable Beta Titanium Alloys
Metals 2018, 8(7), 506; https://doi.org/10.3390/met8070506
Received: 21 May 2018 / Revised: 23 June 2018 / Accepted: 25 June 2018 / Published: 30 June 2018
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Abstract
In this article, we provide a broad and extensive review of beta titanium alloys. Beta titanium alloys are an important class of alloys that have found use in demanding applications such as aircraft structures and engines, and orthopedic and orthodontic implants. Their high
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In this article, we provide a broad and extensive review of beta titanium alloys. Beta titanium alloys are an important class of alloys that have found use in demanding applications such as aircraft structures and engines, and orthopedic and orthodontic implants. Their high strength, good corrosion resistance, excellent biocompatibility, and ease of fabrication provide significant advantages compared to other high performance alloys. The body-centered cubic (bcc) β-phase is metastable at temperatures below the beta transus temperature, providing these alloys with a wide range of microstructures and mechanical properties through processing and heat treatment. One attribute important for biomedical applications is the ability to adjust the modulus of elasticity through alloying and altering phase volume fractions. Furthermore, since these alloys are metastable, they experience stress-induced transformations in response to deformation. The attributes of these alloys make them the subject of many recent studies. In addition, researchers are pursuing development of new metastable and near-beta Ti alloys for advanced applications. In this article, we review several important topics of these alloys including phase stability, development history, thermo-mechanical processing and heat treatment, and stress-induced transformations. In addition, we address recent developments in new alloys, phase stability, superelasticity, and additive manufacturing. Full article
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Open AccessFeature PaperReview Martens-ite
Metals 2018, 8(6), 395; https://doi.org/10.3390/met8060395
Received: 27 April 2018 / Revised: 18 May 2018 / Accepted: 21 May 2018 / Published: 29 May 2018
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Abstract
Martensite and martensitic transformations in metals and alloys have been intensively studied for more than a century and many comprehensive and informative reviews have been published. The current review differs insofar as the analysis is performed largely through the prism of detailed studies
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Martensite and martensitic transformations in metals and alloys have been intensively studied for more than a century and many comprehensive and informative reviews have been published. The current review differs insofar as the analysis is performed largely through the prism of detailed studies of the changes in the martensitic transformation in Fe3Pt alloy as a result of austenite ordering. This important alloy is the first ferrous alloy identified as exhibiting thermoelastic transformation and shape memory. The effect of parent phase order on the martensitic transformation offers significant insights into general understanding of the nature of martensitic transformation, particularly the factors contributing to reversible and irreversible transformation. It is concluded that for crystallograhically reversible transformation to occur both strain limiting and strain accommodating factors must be present and that these factors collectively constitute the sufficient condition for reversible martensitic transformation. Although the crystallography of individual plates formed in a given alloy can change with their temperature of formation, this intrinsic variability has not been considered in analyses using phenomenological theory. Significant variability can exist in measured quantities such as habit plane normals and orientation relationships used to test theoretical predictions. Measured lattice parameters, essential data for theoretical calculations, can also differ from the actual parameters existing at the temperature of plate formation. Full article
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