Crystallographic Features of Martensite Transformed from Ultrafine Grained Austenite Fabricated by Severe Plastic Deformation

2012 ◽  
Vol 706-709 ◽  
pp. 1835-1840
Author(s):  
Akinobu Shibata ◽  
Hamidreza Jafarian ◽  
Daisuke Terada ◽  
Nobuhiro Tsuji
Keyword(s):  
Plastic Deformation ◽  
Orientation Relationship ◽  
Large Deviation ◽  
Martensite Plate ◽  
High Density ◽  
Coarse Grained ◽  
Density Of Dislocations ◽  
Austenite Grain ◽  
Ultrafine Grained ◽  
Sever Plastic Deformation

We studied the crystallographic features, especially the orientation relationship with respect to austenite, of martensite in a steel transformed from coarse-grained equiaxed austenite (35 μm), ultrafine-grained equiaxed (2.5 μm) or lamellar (300nm) austenite fabricated by sever plastic deformation. With decreasing the grain size of equiaxed austenite, the orientation relationship changed from Kurdjumov - Sachs relationship to Greninger - Troiano relationship. We inferred that this change of orientation relationship could be attributed to the small size of martensite plate transformed from the ultrafine-grained equiaxed austenite. The martensite transformed from the ultrafine-grained lamellar austenite did not have a definite orientation relationship with austenite. We considered that a high density of dislocations or a high density of low angle boundaries within the ultrafine lamellar austenite grain resulted in the large deviation of orientation relationship.

scholarly journals Aging Behaviour of Al-Mg-Si Alloys Subjected to Severe Plastic Deformation by ECAP and Cold Asymmetric Rolling

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
S. Farè ◽  
N. Lecis ◽  
M. Vedani
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Isothermal Aging ◽  
Room Temperature ◽  
Coarse Grained ◽  
Peak Shape ◽  
Asymmetric Rolling ◽  
Ultrafine Grained ◽  
Aging Kinetics ◽  
Reduced Intensity

A study was carried out on aging behaviour of a 6082 alloy processed by two different severe plastic deformation techniques: ECAP and asymmetric rolling. Both techniques were able to generate an ultrafine-grained structure in samples processed at room temperature. It was stated that severe straining promotes marked changes in the postdeformation aging kinetics. The peaks of β′′/β′ transition phases were anticipated and of progressively reduced intensity over the coarse grained alloy. A further peak accounting for onset of recrystallization also appeared in the most severely deformed samples. Full consistency in peak shape and position was found when comparing materials processed by ECAP and asymmetric rolling. Isothermal aging treatments performed at 180°C revealed that in the severely deformed samples, aging became so fast that the hardness curves continuously decreased due to overwhelming effects of structure restoration. On the contrary, aging at 130°C offers good opportunities for fully exploiting the precipitate hardening effects in the ultrafine-grained alloy.

Unique Mechanical Properties of Nanostructured Metals

2007 ◽  
Vol 7 (11) ◽  
pp. 3765-3770 ◽  
Author(s):  
Nobuhiro Tsuji
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Grain Size ◽  
Equivalent Strain ◽  
Coarse Grained ◽  
Roll Bonding ◽  
Nanostructured Metals ◽  
Ultrafine Grained ◽  
Nanocrystalline Structures ◽  
Rolling Deformation

Recently, it becomes possible to fabricate bulk metals having ultrafine grained or nanocrystalline structures of which grain size is in nano-meter dimensions. One of the promising ways to realize bulk nanostructured metals is severe plastic deformation (SPD) above logarithmic equivalent strain of 4. We have developed an original SPD process, named Accumulative Roll Bonding (ARB) using rolling deformation in principle, and have succeeded in fabricating bulk nanostructured sheets of various kinds of metals and alloys. The ARB process and the nanostructured metals fabricated by the ARB are introduced in this paper. The nanostructured metals sometimes perform quite unique mechanical properties, that is rather surprising compared with conventionally coarse grained materials. The unique properties seem to be attributed to the characteristic structures of the nano-metals full of grain boundaries.

Influence of Severe Plastic Deformation on Mechanical Properties of an AA5024 Alloy

2016 ◽  
Vol 879 ◽  
pp. 1317-1322 ◽  
Author(s):  
Anna Mogucheva ◽  
Diana Yuzbekova ◽  
Tatiana Lebedkina ◽  
Mikhail Lebyodkin ◽  
Rustam Kaibyshev
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Strength ◽  
Coarse Grained ◽  
Type B ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Elongation To Failure ◽  
Dislocation Strengthening

The paper reports on the effect of severe plastic deformation on mechanical properties of an Al-4.57Mg-0.35Mn-0.2Sc-0.09Zr (in wt. pct.) alloy processed by equal channel angular pressing followed by cold rolling (CR). The sheets of the 5024 alloy with coarse grained (CG) structure exhibited a yield stress (YS) near 410 MPa and an ultimate tensile strength (UTS) of 480 MPa, while the YS and UTS of this material with ultrafine-grained (UFG) structure increased to 530 and 560 MPa, respectively. On the other hand, the elongation to failure decreased by a factor of 2 and 4 after CR and CR following ECAP, respectively. It was shown that dislocation strengthening attributed to extensive CR plays a major role in achieving high strength of this alloy. Besides these macroscopic characteristics, jerky flow caused by the Portevin-Le Chatelier (PLC) instability of plastic deformation was examined. The formation of UFG structure results in a transition from mixed type A+B to pure type B PLC serrations. No such effect on the serrations type was observed after CR.

Characterization of Substructure Evolution in Ferrous Lenticular Martensite

2010 ◽  
Vol 654-656 ◽  
pp. 1-6 ◽  
Author(s):  
Akinobu Shibata ◽  
Shigekazu Morito ◽  
Tadashi Furuhara ◽  
Tadashi Maki
Keyword(s):  
Plastic Deformation ◽  
Thin Plate ◽  
Growth Behavior ◽  
High Density ◽  
Plate Martensite ◽  
Careful Observation ◽  
Density Of Dislocations ◽  
Transformation Twins ◽  
The Difference

This study investigated the substructure evolution in lenticular martensite. The substructure of lenticular martensite changes from fine transformation twins in the midrib and twinned region to a high density of dislocations in the untwinned region during growth. On the basis of careful observation of the morphology and substructure of midrib and examination of the stress-induced growth behavior of thin plate martensite, we concluded that the midrib in lenticular martensite is thin plate martensite itself. Tangled and curved dislocations appeared near the martensite-austenite boundary of the untwinned region in Fe-33Ni and in the entire untwinned region in Fe-31Ni, because the martensite inherited the accommodation dislocations in the surrounding austenite. The difference of Ms temperature causes the difference in the substructure between Fe-33Ni and Fe-31Ni. The higher Ms temperature of Fe-31Ni induces the plastic deformation of the surrounding austenite at an earlier stage of transformation, resulting in the appearance of tangled and curved dislocations in the entire untwinned region.

Measures of Ductility for UFG Materials Obtained by SPD

2009 ◽  
Vol 633-634 ◽  
pp. 223-230 ◽  
Author(s):  
Yan Beygelzimer ◽  
O. Prokof'eva ◽  
R. Kulagin ◽  
Viktor Varyukhin ◽  
Sergey Synkov
Keyword(s):  
Plastic Deformation ◽  
Coarse Grained ◽  
Alloy Structure ◽  
Commercial Grade ◽  
Ultrafine Grained ◽  
Twist Extrusion ◽  
Coarse Grained State ◽  
Ultrafine Grained Materials ◽  
Reduction Of Area ◽  
Discontinuity Flaws

It is shown that for ultrafine grained materials obtained with severe plastic deformation methods, the value of elongation up to fracture does not determine ductility, while the reduction of area up to fracture does determine it. The latter characteristic gives information about how an alloy structure resists the formation of discontinuity flaws under deformation in a hard stress state. We show that for a commercial grade titanium that underwent Twist Extrusion (TE), the value of , and thus ductility, is higher in the UFG state than in the coarse-grained state.

Mechanical and Functional Properties of Titanium Alloys Processed by Severe Plastic Deformation

2011 ◽  
Vol 683 ◽  
pp. 137-148 ◽  
Author(s):  
Vladimir V. Stolyarov
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Mechanical Behavior ◽  
Titanium Alloys ◽  
Functional Properties ◽  
Coarse Grained ◽  
Cyclic Loads ◽  
Metallic Materials ◽  
Ultrafine Grained

Systematized literature data related to the study of mechanical and functional properties of ultrafine-grained and nanostructured metallic materials processed by deformation methods are presented. Special attention is given to the mechanical behavior of titanium materials under tension, as well as under impact and cyclic loads. The advantage of the materials under investigation over their coarse-grained analogues is shown.

The Aspects of Practical Application of Ultrafine-Grained Titanium Alloys Produced by Severe Plastic Deformation

2010 ◽  
Vol 667-669 ◽  
pp. 1183-1187 ◽  
Author(s):  
Evgeny V. Naydenkin ◽  
Ilya V. Ratochka ◽  
Galina P. Grabovetskaya
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Titanium Alloys ◽  
Elevated Temperatures ◽  
Acoustic Properties ◽  
Coarse Grained ◽  
Medical Implants ◽  
Ultrafine Grained ◽  
Mechanical And Physical Properties ◽  
Ultrasound System

The mechanical and physical properties of ultrafine-grained titanium alloys produced by severe plastic deformation are considered. It is found that the formation of ultrafine-grained structure in these materials causes a significant enhancement in their mechanical properties at room temperature and in their resistance to hydrogen embrittlement as well as a change in their acoustic properties. Moreover, superplasticity is realized in these materials at less elevated temperatures relative to the respective coarse grained counterparts. It is shown that the above changes in material properties permit optimization of conditions by the production of items from the titanium alloys, e.g. medical implants having the requisite strength and stepped waveguides having long life even in the high power density conditions of an ultrasound system.

scholarly journals Texture and Young's Modulus Anisotropy in Nanostructured Copper

1999 ◽  
Vol 32 (1-4) ◽  
pp. 321-339 ◽  
Author(s):  
I. V. Alexandrov ◽  
V. N. Serebryany ◽  
L. N. Sarvarova ◽  
M. V. Alexandrova ◽  
R. Z. Valiev
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Young’S Modulus ◽  
Crystallographic Texture ◽  
Young's Modulus ◽  
Coarse Grained ◽  
Elastic Behaviour ◽  
Leading Role ◽  
Ultrafine Grained ◽  
Cold Rolling And Annealing

It was shown that in ultrafine-grained nanostructured Cu processed by severe plastic deformation and subjected to cold rolling and annealing, the level and character of Young's modulus anisotropy is significantly different from values corresponding to cold rolled and annealed coarse-grained Cu. The crystallographic texture formation processes are investigated in these states in parallel. The comparative study of the elastic behaviour and crystallographic texture lets us draw conclusions concerning the leading role of not only developing crystallographic texture but a specific defect structure of grain boundaries as well in the formation of unusual elastic properties of ultrafine-grained materials processed by severe plastic deformation.

A New Deformation Mechanism in Nanoscale Fe-C Composite as a Result of a Stress-Induced α→γ Transformation

2006 ◽  
Vol 503-504 ◽  
pp. 439-446 ◽  
Author(s):  
Julia Ivanisenko ◽  
Ian MacLaren ◽  
Ruslan Valiev ◽  
Hans Jorg Fecht
Keyword(s):  
Plastic Deformation ◽  
Martensitic Transformation ◽  
Severe Plastic Deformation ◽  
Orientation Relationship ◽  
Deformation Mechanism ◽  
Nanocrystalline Structure ◽  
Pearlitic Steel ◽  
Deformation Mechanisms ◽  
Coarse Grained ◽  
Ultrafine Grain

Recent studies of nanocrystalline materials have often found that the deformation mechanisms are radically different to those in coarse-grained materials, resulting in quite different mechanical properties for such materials. The use of pearlitic steels for the study of the deformation mechanisms in bcc materials with ultrafine grain sizes is quite convenient, because it is relatively straightforward to obtain a homogenous nanocrystalline structure with a mean grain size as small as 10 nm using various modes of severe plastic deformation (SPD). In this paper we show that highpressure torsion of an initially pearlitic steel results in a nanostructured steel in which austenite has been formed at or close to room temperature. The orientation relationship between neighboring ferrite and austenite grains is the well-known Kurdjumov-Sachs orientation relationship, i.e. the same observed in temperature-induced martensitic transformation of iron and steels. It is shown that this must have resulted from a reverse martensitic transformation promoted by the high shear strains experienced by the material during severe plastic deformation of the nanocrystalline structure. This transformation represents an alternative deformation mechanism that can be activated when conventional deformation mechanisms such as slip of lattice dislocations become exhausted.

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