Route Bc Research Articles

Texture Evolution as Determined by In situ Neutron Diffraction During Annealing of Iron Deformed by Equal Channel Angular Pressing

In situ neutron diffraction experiments were performed to follow the annealing behavior of iron deformed by equal-channel angular pressing at room temperature using route Bc to a total von Mises strain of evM = 9.2. The temperature was varied from room temperature to 1223 K (950 °C), while neutron diffraction data for quantitative texture analysis were collected at a given temperature when holding for 5 minutes. Pole figures and orientation distribution function maps from neutron diffraction and electron backscatter diffraction measurements were used to follow the changes in crystallographic texture and grain size during annealing. In situ neutron diffraction experiments allowed understanding and identifying texture-related changes that occur during recrystallization, grain growth, and phase transformation in iron.

Microstructure, hardness evolution and thermal stability of binary Al-7Mg alloy processed by ECAP with intermediate annealing

A binary Al-7Mg alloy was processed by equal channel angular pressing (ECAP) at room temperature via route Bc, combined with intermediate annealing. After 6 passes, a high hardness of 218 HV is achieved. Transmission electron microscopy (TEM) observations demonstrate that ECAP leads to a significant grain refinement and ultrafine grains down to 100-200 nm are developed after 5 or 6 passes. X-ray diffraction (XRD) analysis indicates that the major part of Mg atoms are in solid solution in the deformed material, and the possible strengthening effect of Mg solute atom clusters or precipitates is neglected. The high hardness of the 6 pass-treated materials comes mainly from grain boundary strengthening, which contributes about 41% to the total strength, while dislocations and Mg solid solution contribute about 24% and 35% to the remaining strength, respectively. Also, the thermal stability of this severely deformed material was investigated by hardness measurements. The material is relatively stable when annealed at a temperature lower than 250 °C, while annealing at 300 °C leads to a rapid softening of the material.

Microstructure and mechanical properties of a spray deposited SiCp/Al composite processed by hot extrusion and equal channel angular pressing

An ultrahigh strength silicon carbide particle reinforced aluminium matrix composite (SiCp/Al), in which the volume of SiC particles was ∼15% and the initial size was ∼10 μm, was prepared using a spray deposition technique, and then hot extrusion and equal channel angular pressing (ECAP) were performed on the composite to investigate the evolution of microstructures and mechanical properties. Microstructural observations revealed that homogeneous equiaxed grains were obtained and the grain size was reduced from ∼3·0 μm to ∼400 nm after four passes of ECAP using route Bc. SiC particles were broken from ∼10 to ∼2 μm sized fragments by the huge shear stress, and many cavities between the broken SiC particles developed; these cavities derived from the broken SiC particles were filled with the Almatrix. Following T6 heat treatment (comprising solution heat treatment and then artificial aging), the microstructure of the equal channel angular pressed SiCp/Al composite showed a very high stability; the tensile strength, yield strength, modulus and elongation of the composite were 770·0 MPa, 575·0 MPa, 106·6 GPa and 7·4% respectively.

Influence of Route-R on wrought magnesium AZ61 alloy mechanical properties through equal channel angular pressing

A new fundamental route entitled ‘Route-R’ is introduced to refine the grains in the material through Equal Channel Angular Pressing (ECAP) process. In route R, specimen is inverted to the original position in each ECAP pass. In the present work, AZ61 alloy is processed using ECAP process for three different fundamental routes mainly route A, route Bc, and route R. ECAP experiment is carried out on AZ61 alloy at lower temperature of 483 K up to two passes. Microstructural characterization is evaluated on unECAPed and ECAPed specimens for three routes. Average grain size of the alloy is to be reduced from 66 μm to 16 μm, 14.1 μm and 10 μm for route A routes Bc, and route R respectively. Vickers microhardness of the alloy is found to be 60 HV for as received material. This microhardness of the alloy is increased to 71 HV, 72 HV, and 74 HV for route A, route Bc, and route R respectively. Mechanical properties of the AZ61 alloy are observed to be route R is providing maximum YS, UTS, and percentage elongation than other route A and route Bc. Tensile fracture topography of the specimen is analyzed using three different routes for two passes.

The Role of Deformation Banding in Grain Refinement under ECAP

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.

Development of Homogeneity in an Al-6061 Alloy Processed by ECAP and ECAP-Conform

Equal-channel angular pressing (ECAP) has been established as an effective method to achieve ultrafine-grained materials and ECAP combined with the Conform process (ECAP-Conform) is considered a promising candidate to realize continuous processing by ECAP. This paper describes experiments conducted on samples of an Al-6061 alloy in order to evaluate the homogeneity development of the alloy processed by ECAP and ECAP-Conform. The samples of the Al-6061 alloy were processed by ECAP and ECAP-Conform at room temperature up to 4 passes via route BC. The microhardness measurements were recorded both in the cross-sectional planes and along the longitudinal directions of the samples. The results show the alloy obtained significant strengthening using both processes. There was reasonable plastic isotropy after 4 passes of ECAP-Conform in both the cross-sectional plane and the longitudinal direction and the alloy showed a homogeneous microhardness distribution in the cross-sectional plane after 4 passes of conventional ECAP.

Effect of Equal Channel Angular Pressing (ECAP) on microstructure and properties of Al-FeAlCr intermetallic phase composites

An aluminium matrix composite was prepared by mixing commercial aluminium powders and 15 vol % of FeAlCr powders and consolidation by hot extrusion. The extruded composite was subjected to severe plastic deformation by equal channel angular pressing (ECAP) at room temperature and at 150°C. The extruded composite presents a uniform distribution of particles although some defects are observed such as residual pores and particle agglomerates. The particle distribution does not show a significant change due to ECAP. The extruded composite exhibits a relatively fine grain size of the order of 1-2 μm that was refined to 550 nm after three ECAP passes at room temperature by route A and to 636 nm after four passes at 150°C by route Bc. The yield stress of the composites was increased by 140 to 180% after ECAP as compared with the extruded condition.

Equal channel angular pressing of copper wire

A new development of equal channel angular pressing method to fabricate wire-formed samples has been proposed and experimented. In this approach, wire-formed specimen, which is inserted inside a polyurethane rubber pad material, has been pressed using conventional equal channel angular pressing die. Commercial pure copper samples in the shape of wire have been equal channel angular pressed up to 12 passes by route BC, and then hardness behavior, electrical conductivity and microstructure observation of deformed samples have been examined. The results indicate that about 77% and 66% enhancements at the hardness value (HV) magnitudes have been obtained after 8th and 12th passes, respectively, as compared to the unequal channel angular pressed state. Reductions of about 92% and 95% at the grain size of pure copper have been observed after 8th and 12th passes, respectively, in comparison with the annealed condition. Also, the first pass of equal channel angular pressed wire has both the worst hardness distribution homogeneity and the lowest electrical resistivity. On the other hand, the final pass of pressed wire has both the best hardness dispersal uniformity and the highest electrical resistivity.

Effect of ECAP Deformation Route on the Degree of Anisotropy of Microstructure of Extremely Low CN Fe-20mass%Cr Alloy

The effect of the deformation route on the microstructural evolution of low CN Fe-20%Cr alloy by ECAP has been investigated, with a focus on the anisotropy of the microstructure. This alloy was pressed at 423 K from one, two and four passes via routes A, Bc and C, and the microstructure was observed three dimensionally. As has been acknowledged, overall grain fragmentation proceeded most effectively in route Bc, and the highest hardness was obtained following routes C and A. However, the degree of anisotropy of microstructural development is different among the three deformation routes. The fractions of the high angle grain boundary (HAGB) and mean grain boundary misorientation were high and nearly isotropic in route Bc, whereas they are considerably low in one direction and highly anisotropic in routes A and C. Most importantly, those two parameters and hardness are the highest in route C if limited to the transverse direction, i.e., normal to both the insert and extruding directions. This result contrasts with FCC materials which most papers report as having the highest fraction of HAGB in route Bc. This result can be interpreted by the slip irreversibility of screw dislocations which is predominant in BCC metals.

Investigation of a new route for equal channel angular pressing process using three-dimensional finite element method

The microstructure and mechanical properties of the deformed materials obtained by equal channel angular pressing are strongly dependent on the amount of induced strain and strain homogeneity developed during history of the process. In this work, a new route for equal channel angular pressing process was proposed and investigated by finite element method. This new route consists of a combination of Routes BC and C by alternating rotations through 90° and 180° after every pass. In other words, the billet is rotated 180° after the first and the third passes around its longitudinal axis like Route C and after the second pass is rotated 90° around its longitudinal axis like Route BC. In comparison with other routes, it was shown that the strain homogeneity achieved by this proposed route is better than other conventional routes. The finite element method results for Route BC were validated by available experimental data, which can support finite element method results for the new proposed route.

Fractographic Analysis of 5052 Al-Mg Alloys Processed by Equal Channel Angular Pressing

In this work, ECAP technique has been applied to 5052 Al-Mg alloys where the alloys find wide application in building and construction, automotive, cryogenic and marine applications. The alloy samples extruded by ECAP with four different deformation routes for 4 passes each were tensile tested and the observation of the fracture surfaces were carried out by using digital camera and Scanning Electron Microscope (SEM). The experimental results showed that the initial pre-annealed sample showed cup and cone shape of fracture, whereas the fractured ECAPed samples of all deformation routes exhibited shear feature in which the fracture surface made an angle with pressing direction of ECAP. The change of size and shape of dimples fracture from larger and irregular shape dimples in initial sample to much smaller and grains-look like dimples in ECAPed sample indicating the grain refinement occurred after ECAP. Among the ECAP deformation routes applied, route BC resulted in smallest dimples size, i.e. about below 2 mm in average. The post annealing subjected to ECAP samples recovered almost completely the fracture feature and fracture morphology to that of the initial one, which was achieved after annealing at 300°C.

Route Effect on Equal Channel Angular Pressing of Copper Tube

A new technique to produce ultra-fine grained tubular specimen has been proposed, and the experiments have been performed using equal channel angular pressing (ECAP) with an angle of 90° between two intersecting channels and also the use of rubber pad as a mandrel during process. Commercial purity copper tubes have been pressed up to three passes through four different fundamental routes (A, BA, BC, and C) directions of which are identified in the text below. The influence of each route on the value, distribution, and homogeneity of hardness has been investigated by applying Vickers micro-hardness measurements at various locations of the tube’s transverse planes. Significant enhancement of the hardness is observed after the first pass ECAP. Also, routes C and BC show, respectively, better average hardness magnitude and hardness distribution uniformity. In addition, the results indicate that there is about 50% and 62% reduction of the grain size, compared to the annealed condition, following ECAP process of the copper tube sample after the first and the third pass via route BC.

Microstructure and mechanical properties of Al-7075 alloy processed by equal channel angular pressing combined with aging treatment

In order to examine the combined effect of plastic deformation and aging process, the Al 7075 alloy was subjected to equal channel angular pressing (ECAP) deformation by route BC in various ECAP and aging conditions: pre-ECAP aging, post-ECAP aging and dynamic aging during ECAP at 393K and 423K. Followed by ECAP and aging treatment, Vickers microhardness and tensile test were performed and microstructural observations were undertaken using transmission electron microscopy (TEM) and X-ray diffractometer (XRD). TEM investigation showed that ultrafine-grained (UFG) materials with grain size less than 500nm could be obtained after three or four passes of ECAP. Precipitates characterization revealed that maximum mechanical properties are achieved when the microstructure mainly consists of fine dispersion of small η′ precipitates and minor quantities of GP zones. Dynamic aged specimens at 393K and 423K represented maximum and minimum mechanical properties, respectively, due to formation of fine η′ precipitates plus GP zones and η′ plus η precipitates, respectively. Dynamic aging during ECAP at 393K appeared preferable to other procedures for attaining maximum mechanical properties as well as saving time and energy.

Effect of Processing Routes on AZ31 Alloy Processed By Severe Plastic Deformation

Equal Channel Angular Pressing (ECAP) is one of the promising techniques in Severe Plastic Deformation (SPD) used to refine the grain size of the metals and its alloys. The main aim of the present study is to give an in depth knowledge of effect of processing routes on AZ31 alloy in ECAP process. In this, processing route A, route C, and route Bc are used to refine the grain size of AZ31 alloy up to two ECAP passes at a temperature of 498K. Initial average grain size of the as received material was found to be 31.8μm. Further, it was reduced to 14.0μm, 15.9μm and 13.3μm for processing route A, route C, and route Bc respectively. Mechanical properties of the AZ31 alloy are experimentally evaluated for three processing routes. The percentage elongation of the material was found to be increased with increasing number of passes. Maximum microhardness of the material was observed in route Bc when compared to route A and route C.

The Effect of ECAP Deformation Route on Microstructure, Mechanical and Electrochemical Properties of Low CN Fe-20%Cr Alloy

The effect of the deformation route on the microstructure, and the mechanical and electrochemical properties of low CN Fe-20%Cr alloy by equal channel angular pressing, have been investigated focusing on the anisotropy of the microstructure. This alloy was pressed at 423 K from one, two and four passes via routes A, Bc and C, and the microstructure was observed in three orthogonal planes. As has been acknowledged, overall grain fragmentation proceeded most effectively in route Bc. However, the degree of anisotropy of microstructural development was different among the three deformation routes. The fractions of the high angle grain boundary and mean grain boundary misorientation were high and nearly isotropic in route Bc, whereas they were consi- derably low in one direction and highly anisotropic in routes A and C. Most importantly, those two parameters were the highest in route C if limited to the transverse direction (Y-plane), i.e. normal to both the insert and extruding directions. This result contrasted with FCC materials, which was reported by most papers having the highest fraction of high angle grain boundary (HAGB) in route Bc. Ultrafine grained structure with the highest HAGB on Y-plane in route C exhibited the most stabilized corrosion behavior.

Microstructure and Mechanical Properties of AISI 8620 Steel Processed by ECAP

ABSTRACTThe aim of this work is to process by equal channel angular pressing (ECAP) a low carbon – triple-alloyed steel containing 0.2% C, 0.5% Cr, 0.6% Ni, 0.2% Mo and 0.8 Mo. The process is performed at room temperature for up to four passes using route Bc with an equivalent strain of ∼0.6 after a single pass. Structure evolution before and after deformation is studied using scanning electron microscopy (SEM) and x-ray diffraction (XRD) and mechanical properties are assessed by microhardness and tensile testing. A significant improvement of the mechanical properties is found with increasing number of ECAP passes. Micro-hardness increases from 216 HV for the initial sample to 302 HV after four passes and tensile strength increases to 1200 MPa compared with 430 MPa prior to ECAP. X-ray diffraction and SEM analysis show changes in the original ferritic-perlitic structure through ferrite grain refinement and the deformation of perlite. This nickel-chromium-molybdenum alloy is used in manufacturing as gear material, and when it is hardened and formed through carburizing or boronizing it can be used to make hard-wearing machine parts. However, the ECAP process has not been used to harden this steel and to change its structure to obtain better mechanical performance.

Mechanical and Microstructural Evaluation of InsituAluminium Titanium Boride Composite Processed by Severe Plastic Deformation

Nanostructured and ultrafine grained metallic materials have received great attention in recent times because of their unique mechanical, physical properties and high performance. High specific strength of the material is critical for many structural applications in automotive and aerospace design. Different techniques for producing ultra-fine-grained (UFG) materials have been introduced especially in the last decade. Severe plastic deformation (SPD) is one such process to obtain ultrafine grains wherein simple shear stress is applied to a billet during multiple passages through an angled channel of constant cross section. One of such process is equal channel angular pressing (ECAP), which is widely used than any other SPD technique to obtain fine grains. The process is capable of generating very large plastic strains that significantly refines the microstructure without altering the external dimension of the billet and therefore has attracted the attention of a number of researchers underlining the potentials to scale up for industrial applications.In this paper an attempt is made to highlight the significance of severe plastic deformation of insitualuminium titanium boride composite. The composite was processed up to 2 passes following Bc route of ECAP. The hardness, ultimate tensile strength with varied reinforcement content of the ECAP samples were found to be significantly high as compared to ascast matrix alloy. While the microstructure analysis revealed progressive refinement of grains after every pass of ECAP.

Effect of equal channel angular pressing on AZ31 wrought magnesium alloys

AZ31 wrought magnesium alloys are light weight materials which play an important role in order to reduces the environmental burdens in modern society because of its high strength to weight ratio, corrosion resistance, and stiffness and machinability. Applications of this material are mainly in structural component i.e., in constructions, automobile, aerospace, electronics and marine industries. In the present work, the microstructure characterization of the AZ31 alloys up to four ECAP passes at temperature of 573 K was observed for route Bc. Average grain size of the material was reduced from 31.8 μm to 8 μm after four ECAP passes. Mechanical properties of the alloy improved with increase in number of ECAP passes. Moreover, X-ray diffraction analysis was carried out for as received and ECAP processed material. Equal channel angular pressing (ECAP) technique is used to refine the grains into ultrafine grain size of the material. In the present work, AZ31 wrought Mg alloy is used as a material processed through ECAP up to 4 passes at the temperature of 573 K for route Bc. Initially, the Average grain size of the as received material was found to be 31.8 μm. The average reduced grain size after 4 ECAP passes was found to be 8 μm. Mechanical properties of the AZ31 alloy was studied for 4 ECAP passed specimen and an improvement was found to have occurred in comparison to as received material. X-ray diffraction analysis has been done for as received material, after homogenized specimen and after 4 ECAP processed specimen. • ECAP experiment carried out using die angle 120° and arc of curvature was 30°. • AZ31 material was deformed at a processing temperature of 573 K up to 4 pass. • Examine the grain refinement with increased ECAP passes for route Bc. • Microstructural Characterization was observed for AZ31 alloy using OM and SEM. • Evaluate the Mechanical properties and X-ray diffraction analysis of AZ31 alloy.

ZK60 alloy processed by ECAP: Microstructural, physical and mechanical characterization

Lately, magnesium alloys have been extensively investigated through severe plastic deformation (SPD) methods in order to extend their application to structural components. In the present work, as-extruded ZK60 magnesium alloy samples were subjected to 4 passes of equal-channel angular pressing (ECAP) at a processing temperature of 250°C, following route Bc. The microstructural evolution of the deformed grains was analyzed using electron back-scattered diffraction (EBSD). The Orientation Imaging Microscopy (OIM) maps, together with the grain boundary misorientation distribution showed a reduction in the grain size accompanied by a large proportion of high angle grain boundaries. Calorimetric analysis showed a slight increase in the recrystallization temperature of the ECAPed magnesium samples. Mechanical tests showed an improvement in the elongation-to-failure after 4 ECAP passes, which were about 2 times higher than in the as-extruded sample. Also a brittle to ductile transition was observed.

Mechanical Properties and Microstructure of AZ31B Magnesium Alloy Processed by I-ECAP

Abstract Incremental equal channel angular pressing (I-ECAP) is a severe plastic deformation process used to refine grain size of metals, which allows processing very long billets. As described in the current article, an AZ31B magnesium alloy was processed for the first time by three different routes of I-ECAP, namely, A, BC, and C, at 523 K (250 °C). The structure of the material was homogenized and refined to ~5 microns of the average grain size, irrespective of the route used. Mechanical properties of the I-ECAPed samples in tension and compression were investigated. Strong influence of the processing route on yield and fracture behavior of the material was established. It was found that texture controls the mechanical properties of AZ31B magnesium alloy subjected to I-ECAP. SEM and OM techniques were used to obtain microstructural images of the I-ECAPed samples subjected to tension and compression. Increased ductility after I-ECAP was attributed to twinning suppression and facilitation of slip on basal plane. Shear bands were revealed in the samples processed by I-ECAP and subjected to tension. Tension–compression yield stress asymmetry in the samples tested along extrusion direction was suppressed in the material processed by routes BC and C. This effect was attributed to textural development and microstructural homogenization. Twinning activities in fine- and coarse-grained samples have also been studied.