The EBSD Investigation on Microstructure Evolution in Fe-32%Ni Alloy during Multi-Axial Forging

Strain Path ◽

High Angle ◽

Deformation Bands ◽

Electron Backscattered Diffraction ◽

Loading Direction ◽

Ni Alloy ◽

Coarse Grains ◽

The microstructure evolution taking place in Fe-32%Ni alloy during multi-axial forging was investigated by electron backscattered diffraction (EBSD). The samples were compressed with loading direction changed through 90º from pass to pass at temperature of 650°C and a strain rate of 10-1/s. The results show the microstructure evolution is characterized by continuous grain subdivision process, i.e. the multi-axial forging promotes the development of deformation bands in various direction followed by their frequent intersection in grain interiors with changing of strain path, which results in continuous fragmentation of coarse grains into subgrains. Concurrently the misorientations of subgrain boundaries rise gradually with repetitive deformation followed by their progressive transformation into high angle boundaries. The ultra-fine grains are concluded to evolve by continuous dynamic recrystallization (CDRX).

Effect of Warm Deformation on Ferrite Microstructure Evolution in a Ti-Microalloyed Steel

10.4028/www.scientific.net/msf.558-559.497 ◽

2007 ◽

Vol 558-559 ◽

pp. 497-504

Author(s):

Beitallah Eghbali

Keyword(s):

Microalloyed Steel ◽

Early Stage ◽

Microstructural Analysis ◽

Optical Microscope ◽

Low Carbon ◽

High Angle ◽

Warm Deformation ◽

Warm deformation is one of the promising hot rolling strategies for producing thin hot rolled steel strips. A better understanding of the microstructure evolution during warm deformation is important for a successful introduction of such processing into the industrial production. In the present research, the effect of deformation strain on the ferrite microstructure development in a low carbon Ti-microalloyed steel was investigated through warm torsion testing. Microstructural analysis with optical microscope and electron back-scattering diffraction was carried out on the warm deformed ferrite microstructures. The results show that at the early stage of deformation an unstable subboundaries network forms and low angle boundaries are introduced in the original grains. Then, with further straining, low angle boundaries transform into high angle boundaries and stable fine equiaxed ferrite grains form. It was considered that dynamic softening and dynamically formation of new fine ferrite grains, with high angle boundaries, were caused by continuous dynamic recrystallization of ferrite.

Ultra-Fine Grained Fe-32%Ni Alloy Processed by Multi-Axial Forging

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.97-101.187 ◽

2010 ◽

Vol 97-101 ◽

pp. 187-190 ◽

Cited By ~ 6

Author(s):

Bao Jun Han

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Strain Path ◽

Internal Stresses ◽

Deformation Bands ◽

Fine Grained ◽

Transmission Electron ◽

Ni Alloy ◽

Equiaxed Grains

The Fe-32%Ni alloy was multi-axially forged at the temperature of 873K and strain rate of 10-2s-1, then the microstructure evolution in Fe-32%Ni alloy during deformation was investigated by the transmission electron microscopy (TEM). The results show that the grain size decreases with strain. The severe plastic deformed microstructure is characterized by the ultra-fine equiaxed grains and high internal stresses. The microstructure evolution mechanism is presented as the following: firstly, the dislocations accumulate as deformation bands in some directions with the progress of deformation; then the cellular structured subgrains are formed by continuous intersecting of deformation bands for the changing of strain path; eventually, the ultra-fine structured grains are formed by the subgrains rotation and the dislocations rearrangement.

Microstructure Evolution in an Al-Cu-Mg-Ag Alloy during ECAP at 300°C

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.409.41 ◽

2011 ◽

Vol 409 ◽

pp. 41-46

Author(s):

Marat Gazizov ◽

Rustam Kaibyshev

Keyword(s):

Dynamic Recrystallization ◽

Equal Channel Angular Pressing ◽

Solution Treatment ◽

Total Strain ◽

High Angle ◽

Angular Pressing ◽

Continuous Dynamic ◽

Average Size

A novel Al-Cu-Mg-Ag alloy with small additions of zirconium and scandium was subjected to equal channel angular pressing (ECAP) by using route BC at 300°C to strains ranging from ~1 to ~12. Initially, the alloy was subjected to solution treatment followed by water quenching; subsequent overageing was carried out at 380°C for 3 h. It was shown that continuous dynamic recrystallization (CDRX) occurs during ECAP resulting in partially recrystallized structure; at a total strain of ~12, the portion of high-angle boundaries (HAB) attains 50 pct., average misorientation is ~25°. Crystallites having elongated shape and an average size of ~1 μm are evolved after a total strain of ~12.

Mechanisms of Microstructure Refinement in Titanium during “abc” Deformation at 400°C

10.4028/www.scientific.net/msf.667-669.439 ◽

2010 ◽

Vol 667-669 ◽

pp. 439-444

Author(s):

Sergey V. Zherebtsov ◽

Egor A. Kudryavtsev ◽

Gennady A. Salishchev

Keyword(s):

Coincidence Site Lattice ◽

Pure Titanium ◽

High Angle ◽

Microstructure Refinement ◽

Commercial Pure Titanium ◽

S Curve ◽

Continuous Dynamic ◽

Flow Stage

Mechanical behavior and microstructure evolution of commercial pure titanium during successive compressions of samples along three orthogonal directions (or so-called “abc” deformation) at 400°C and strain rate 10-3s-1 were studied. The cumulative S- curve demonstrates a steady state flow stage following the intensive strengthening. The microstructure evolution of titanium during first increments of “abc” deformation is associated with twinning and shear deformation. Further deformation results in microstructure refinement due to transformation of coincidence site lattice twin boundaries to high-angle arbitrary ones and formation of high-angle deformation induced boundaries. Another mechanism of new grains formation is continuous dynamic recrystallization.

Microstructural Evolution and Deformation Mechanisms for Superplasticity of NiAl Intermetallic

10.4028/www.scientific.net/msf.475-479.2995 ◽

2005 ◽

Vol 475-479 ◽

pp. 2995-2998

Author(s):

Jian Ting Guo ◽

Rong Shi Chen ◽

Xing Hao Du ◽

Gu Song Li ◽

Lan Zhang Zhou

Keyword(s):

Electron Microscopy ◽

Microstructural Evolution ◽

Superplastic Deformation ◽

Tensile Elongation ◽

Deformation Mechanisms ◽

High Angle ◽

Transmission Electron ◽

Continuous Dynamic ◽

Temperature Strain

The microstructural evolution during superplastic deformation of the extruded stoichiometric NiAl polycrystals were systemically investigated in various conditions of temperature, strain rate and strain by means of optical microscopy (OM) and transmission electron microscopy (TEM). Consequently, The deformation microstructures corresponding to the large tensile elongation consisted of subgrains, low angle grains as well as high angle grains, which indicated that continuous dynamic recrystallization (CDRX) process was operating during superplastic deformation.

The Role of Deformation Banding in Grain Refinement under ECAP

10.4028/www.scientific.net/msf.783-786.2641 ◽

2014 ◽

Vol 783-786 ◽

pp. 2641-2646 ◽

Cited By ~ 2

Author(s):

Rustam Kaibyshev ◽

Sergey Malopheyev ◽

Vladislav Kulitskiy ◽

Marat Gazizov

Keyword(s):

Dynamic Recrystallization ◽

Grain Refinement ◽

Lamellar Structure ◽

True Strain ◽

High Angle ◽

Angular Pressing ◽

Deformation Banding ◽

The mechanism of grain refinement in an Al-5.4Mg-0.4Mn-0.2Sc-0.09Zr alloy subjected to equal-channel angular pressing (ECAP) at 300°C through route BC is considered. It was shown that the formation of geometrically necessary boundaries (GNB) aligned with a {111} plane at ε≤1 initiates the occurrence of continuous dynamic recrystallization (CDRX). Upon further strain the GNBs transform to low-to-moderate angle planar boundaries that produces lamellar structure. In the strain interval 2-4, 3D arrays of planar boundaries evolve due to inducing the formation of 2nd order and higher orders families of GNBs in new {111} planes. GNBs gradually convert to high-angle boundaries (HAB) with strain. A uniform recrystallized structure is produced at a true strain of ∼8. The role of slip concentration and shearing patterns in the formation of GNBs is discussed.

Grain Refinement in Magnesium Alloy AZ31 during Hot Deformation

10.4028/www.scientific.net/msf.467-470.531 ◽

2004 ◽

Vol 467-470 ◽

pp. 531-536 ◽

Cited By ~ 8

Author(s):

Xu Yue Yang ◽

Hiromi Miura ◽

Taku Sakai

Keyword(s):

Magnesium Alloy ◽

Kink Bands ◽

Alloy Az31 ◽

Magnesium Alloy Az31 ◽

Structure Changes ◽

Coarse Grains ◽

Grain Fragmentation ◽

Continuous Reaction ◽

The deformation behavior and structure changes of magnesium alloy AZ31 were studied in compression at temperatures ranging from 523K to 673K and at a strain rate of 3 x 10-3 s-1. They depend sensitively on deformation temperature. At high temperatures, grain fragmentation takes place due to frequent formation of kink bands initially at corrugated grain boundaries and then in grain interiors, followed by full development of new grains in high strain. At lower temperatures, in contrast, twinning takes place in rather coarse grains and kink bands are formed mainly in finer original ones in low strain. It is concluded that new grain evolution can be controlled by a deformation-induced continuous reaction resulting in grain fragmentation by kink bands, i.e. continuous dynamic recrystallization (cDRX). The latter is discussed comparing with conventional, i.e. discontinuous, DRX.

Microstructure Evolution of Ti-5Al-5V-5Mo-3Cr after Hot Deformation at Large and Moderate Strains

10.4028/www.scientific.net/msf.941.1443 ◽

2018 ◽

Vol 941 ◽

pp. 1443-1449 ◽

Cited By ~ 1

Author(s):

María Cecilia Poletti ◽

Ricardo Buzolin ◽

Sanjev Kumar ◽

Peng Wang ◽

Thierry Franz Jules Simonet-Fotso

Keyword(s):

Hot Deformation ◽

Beta Phase ◽

Internal Variable ◽

Alpha Phase ◽

Large Strains ◽

High Angle ◽

Wide Range ◽

Hot Torsion ◽

This work deals with the analysis and modelling of the microstructural evolution of the metastable titanium alloy Ti-5Al-5V-5Mo-3Cr during hot deformation up to moderate and large strains. Experimental flow curves and deformed samples are obtained by hot compression and hot torsion tests using a Gleeble ® 3800 device. The samples are deformed above and below the beta transus temperature and in a wide range of strain rates. Microstructures are characterized after deformation and in-situ water quenching using light optical and scanning electron microscopy and electron back scattered diffraction (EBSD). Dynamic recovery of the beta phase is found to be the main deformation mechanism up to moderated strains. By increasing the strain, continuous dynamic recrystallization (cDRX) is confirmed by the progressive conversion of low angle boundaries into high-angle boundaries. Alpha phase plays a secondary role in the deformation of the material by pinning the movement of beta high angle grain boundaries (HAGB). The evolution of the microstructure is modelled using dislocation density as internal variable in the single β field.

Microstructure Evolution of 316L Steel Prepared with the Use of Additive and Conventional Methods and Subjected to Dynamic Loads: A Comparative Study

Materials ◽

10.3390/ma13214893 ◽

2020 ◽

Vol 13 (21) ◽

pp. 4893

Author(s):

Michał Ziętala ◽

Tomasz Durejko ◽

Robert Panowicz ◽

Marcin Konarzewski

Keyword(s):

Stainless Steel ◽

316L Stainless Steel ◽

Hot Forging ◽

Dynamic Loads ◽

Dislocation Slip ◽

Full Density ◽

High Angle ◽

Electron Backscattered Diffraction ◽

316L Steel

The mechanical properties and microstructure evolution caused by dynamic loads of 316L stainless steel, fabricated using the Laser Engineered Net Shaping (LENS) technique and hot forging method were studied. Full-density samples, without cracks made of 316L stainless steel alloy powder by using the LENS technique, are characterized by an untypical bi-modal microstructure consisting of macro-grains, which form sub-grains with a similar crystallographic orientation. Wrought stainless steel 316L has an initial equiaxed and one-phase structure, which is formed by austenite grains. The electron backscattered diffraction (EBSD) technique was used to illustrate changes in the microstructure of SS316L after it was subjected to dynamic loads, and it was revealed that for both samples, the grain refinement increases as the deformation rate increases. However, in the case of SS316L samples made by LENS, the share of low-angle boundaries (sub-grains) decreases, and the share of high-angle boundaries (grains of austenite) increases. Dynamically deformed wrought SS316L is characterized by the reverse trend: a decrease in the share of high-angle boundaries and an increase in the share of low-angle boundaries. Moreover, additively manufactured SS316L is characterized by lower plastic flow stresses compared with hot-forged steel, which is caused by the finer microstructure of wrought samples relative to that of additive samples. In the case of additively manufactured 316L steel samples subjected to a dynamic load, plastic deformation occurs predominantly through dislocation slip, in contrast to the wrought samples, in which the dominant mechanism of deformation is twinning, which is favored by a high deformation speed and low stacking fault energy (SFE) for austenite.

Microstructure and Texture Evolution during Continuous Dynamic Recrystallization at Warm Deformation of Titanium

10.4028/www.scientific.net/msf.467-470.1211 ◽

2004 ◽

Vol 467-470 ◽

pp. 1211-1216 ◽

Cited By ~ 1

Author(s):

S.Yu. Mironov ◽

Gennady A. Salishchev ◽

Sergey V. Zherebtsov

Keyword(s):

Texture Evolution ◽

Pure Titanium ◽

Internal Stresses ◽

High Angle ◽

Warm Deformation ◽

Misorientation Distribution ◽

12 Steps ◽

Continuous Dynamic ◽

High Level

The microstructure and texture evolutions in pure titanium during severe plastic deformation at T=400°C were investigated. Compressive deformation of prismatic samples was sequentially applied in three orthogonal directions up to 12 steps and a strain at each step of 40%. A radical microstructure refinement (from 20 to 0.2 µm) during strain has been found. The features of the deformation structure are a high level of internal stresses, high density of dislocations, a large number of deformation induced boundaries and the presence of twins. It is shown that during strain there is a significant change in disorientation angles and axes of individual high angle grain boundaries. At the same time the total set of high angle boundaries - Misorientation Distribution Function (MDF) and texture - does not change significantly with strain. The reasons for the change in disorientation angles and axes at new deformation-induced boundaries during plastic flow are discussed.