Room temperature equal-channel angular pressing of a magnesium alloy

A stent is employed to expand a narrowed tubular organ, such as a blood vessel. However, the persistent presence of a stainless steel stent yields several problems of late thrombosis, restenosis and chronic inflammation reactions. Biodegradable magnesium stents have been introduced to solve these problems. However, magnesium-based alloys suffer from poor ductility and lower than desired fatigue performance. There is still a huge demand for further research on new alloys and stent designs. Then, as fundamental research for this, AZ31 B magnesium alloy has been investigated for the effect of equal-channel angular pressing on the fatigue properties. ECAP was conducted for one pass and eight passes at 300 °C using a die with a channel angle of 90°. An annealed sample and ECAP sample of AZ31 B magnesium alloy were subjected to tensile and fatigue tests. As a result of the tensile test, strength in the ECAP (one pass) sample was higher than in the annealed sample. As a result of the fatigue test, at stress amplitude σa = 100 MPa, the number of cycles to failure was largest in the annealed sample, medium in the ECAP (one pass) sample and lowest in the ECAP (eight passes) sample. It was suggested that the small low cycle fatigue life of the ECAP (eight passes) sample is attributable to severe plastic deformation.

Download Full-text

Experimental and Numerical Investigation of the ECAP Processed Copper: Microstructural Evolution, Crystallographic Texture and Hardness Homogeneity

Metals ◽

10.3390/met11040607 ◽

2021 ◽

Vol 11 (4) ◽

pp. 607

Author(s):

A. I. Alateyah ◽

Mohamed M. Z. Ahmed ◽

Yasser Zedan ◽

H. Abd El-Hafez ◽

Majed O. Alawad ◽

...

Keyword(s):

Grain Size ◽

Equal Channel Angular Pressing ◽

Cross Section ◽

Room Temperature ◽

Pure Copper ◽

High Density ◽

Ecap Processing ◽

Heterogeneous Distribution ◽

Angular Pressing ◽

Average Grain Size

The current study presents a detailed investigation for the equal channel angular pressing of pure copper through two regimes. The first was equal channel angular pressing (ECAP) processing at room temperature and the second was ECAP processing at 200 °C for up to 4-passes of route Bc. The grain structure and texture was investigated using electron back scattering diffraction (EBSD) across the whole sample cross-section and also the hardness and the tensile properties. The microstructure obtained after 1-pass at room temperature revealed finer equiaxed grains of about 3.89 µm down to submicrons with a high density of twin compared to the starting material. Additionally, a notable increase in the low angle grain boundaries (LAGBs) density was observed. This microstructure was found to be homogenous through the sample cross section. Further straining up to 2-passes showed a significant reduction of the average grain size to 2.97 µm with observable heterogeneous distribution of grains size. On the other hand, increasing the strain up to 4-passes enhanced the homogeneity of grain size distribution. The texture after 4-passes resembled the simple shear texture with about 7 times random. Conducting the ECAP processing at 200 °C resulted in a severely deformed microstructure with the highest fraction of submicron grains and high density of substructures was also observed. ECAP processing through 4-passes at room temperature experienced a significant increase in both hardness and tensile strength up to 180% and 124%, respectively.

Download Full-text

Simulation of deformation and fracture initiation during equal channel angular pressing of AZ31 magnesium alloy with covered tube casing

Journal of Materials Research and Technology ◽

10.1016/j.jmrt.2021.03.096 ◽

2021 ◽

Author(s):

A.R. Eivani ◽

S.M. Mirghasemi ◽

S.H. Seyedein ◽

J. Zhou ◽

H.R. Jafarian

Keyword(s):

Magnesium Alloy ◽

Equal Channel Angular Pressing ◽

Fracture Initiation ◽

Az31 Magnesium Alloy ◽

Angular Pressing ◽

Deformation And Fracture

Download Full-text

Effect of Equal-Channel Angular Pressing (ECAP) on Creep in Aluminium Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.539-543.2904 ◽

2007 ◽

Vol 539-543 ◽

pp. 2904-2909 ◽

Cited By ~ 15

Author(s):

Vàclav Sklenička ◽

Jiří Dvořák ◽

Marie Kvapilová ◽

Milan Svoboda ◽

Petr Král ◽

...

Keyword(s):

Equal Channel Angular Pressing ◽

Aluminium Alloys ◽

Creep Resistance ◽

Room Temperature ◽

Creep Behaviour ◽

Coarse Grained ◽

Pure Aluminium ◽

Creep Tests ◽

Angular Pressing ◽

Compression Creep

This paper examines the effect of equal-channel angular pressing (ECAP) on creep behaviour of pure aluminium, binary Al-0.2wt.%Sc alloy and ternary Al-3wt.%Mg-0.2wt.%Sc alloy. The ECAP was conducted at room temperature with a die that had a 90° angle between the channels and 8 repetitive ECAP passes followed route BC. Constant stress compression creep tests were performed at 473 K and stresses ranging between 16 to 80 MPa on ECAP materials and, for comparison purposes, on the initial coarse-grained materials. The results showed that the creep resistance of the ECAP processed Al-Sc and Al-Mg-Sc alloys was markedly deteriorated with respect to unpressed coarse-grained materials.

Download Full-text

Processing of Copper by Equal Channel Angular Pressing (ECAP) – Microstructure Investigations

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.641.286 ◽

2015 ◽

Vol 641 ◽

pp. 286-293

Author(s):

Beata Leszczyńska-Madej ◽

Maria W. Richert ◽

Agnieszka Hotloś ◽

Jacek Skiba

Keyword(s):

Equal Channel Angular Pressing ◽

Room Temperature ◽

Subgrain Size ◽

Pure Copper ◽

Shear Bands ◽

Angular Pressing ◽

Ecap Process ◽

Transmission Electron ◽

Different Types ◽

Diffraction Patterns

The present study attempts to apply Equal-Channel Angular Pressing (ECAP) to 99.99% pure copper. ECAP process was realized at room temperature for 4, 8 and 16 passes through route BC using a die having angle of 90°. The microstructure of the samples was investigated by means both light and transmission electron microscopy. Additionally the microhardness was measured and statistical analysis of the grains and subgrains was performed. Based on Kikuchi diffraction patterns misorientation was determined. There were some different types of bands in the microstructure after deformation. The shear bands, bands and in the submicron range the microshear bands and microbands are a characteristic feature of the microstructure of copper. Also characteristic was increasing of the number of bands with increasing of deformation and mutually crossing of the bands. The intersection of a bands and microbands leads to the formation of new grains with the large misorientation angle. The measured grain/subgrain size show, that the grain size is maintained at a similar level after each stage of deformation and is equal to d = 0.25 – 0.32 μm.

Download Full-text

Numerical Simulation of Microstructure Evolution in AZ31 Magnesium Alloy during Equal Channel Angular Pressing

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.609-610.495 ◽

2014 ◽

Vol 609-610 ◽

pp. 495-499

Author(s):

Guo Cheng Ren ◽

Xiao Juan Lin ◽

Shu Bo Xu

Keyword(s):

Finite Element ◽

Magnesium Alloy ◽

Equal Channel Angular Pressing ◽

Microstructure Evolution ◽

Element Model ◽

Az31 Magnesium Alloy ◽

Angular Pressing ◽

Ecap Process ◽

Element Simulation ◽

3D Software

The microstructure and material properties of AZ31 magnesium alloy are very sensitive to process parameters, which directly determine the service properties. To explore and understand the deformation behavior and the optimization of the deformation process, the microstructure evolution during equal channel angular pressing was predicted by using the DEFORM-3D software package at different temperature. To verify the finite element simulation results, the microstructure across the transverse direction of the billet was measured. The results show that the effects strain and deformation temperatures on the microstructure evolution of AZ31 magnesium during ECAP process are significant, and a good agreement between the predicted and experimental results was obtained, which confirmed that the derived dynamic recrystallization mathematical models can be successfully incorporated into the finite element model to predict the microstructure evolution of ECAP process for AZ31 magnesium.

Download Full-text

Strength of Commercial Aluminum Alloys after Equal Channel Angular Pressing and Post-ECAP Processing

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.114.91 ◽

2006 ◽

Vol 114 ◽

pp. 91-96 ◽

Cited By ~ 10

Author(s):

Maxim Yu. Murashkin ◽

M.V. Markushev ◽

Julia Ivanisenko ◽

Ruslan Valiev

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Tensile Strength ◽

Aluminum Alloys ◽

Ultimate Tensile Strength ◽

Equal Channel Angular Pressing ◽

Room Temperature ◽

Solution Treatment ◽

Ecap Processing ◽

Angular Pressing

The effects of equal channel angular pressing (ECAP), further heat treatment and rolling on the structure and room temperature mechanical properties of the commercial aluminum alloys 6061 (Al-0.9Mg-0.7Si) and 1560 (Al-6.5Mg-0.6Mn) were investigated. It has been shown that the strength of the alloys after ECAP is higher than that achieved after conventional processing. Prior ECAP solution treatment and post-ECAP ageing can additionally increase the strength of the 6061 alloy. Under optimal ageing conditions a yield strength (YS) of 434 MPa and am ultimate tensile strength (UTS) of 470 MPa were obtained for the alloy. Additional cold rolling leads to a YS and UTS of 475 and 500 MPa with 8% elongation. It was found that the post-ECAP isothermal rolling of the 1560 alloy resulted in the formation of a nano-fibred structure and a tensile strength (YS = 540 MPa and UTS = 635 MPa) that has never previously been observed in commercial non-heat treatable alloys.

Download Full-text

Isothermal Continuous Equal Channel Angular Pressing of Magnesium Alloy AZ31

JOM ◽

10.1007/s11837-020-04195-4 ◽

2020 ◽

Vol 72 (7) ◽

pp. 2603-2611

Author(s):

Casey F. Davis ◽

Adam J. Griebel ◽

Terry C. Lowe

Keyword(s):

Magnesium Alloy ◽

Equal Channel Angular Pressing ◽

Alloy Az31 ◽

Magnesium Alloy Az31 ◽

Angular Pressing

Download Full-text