Cyclic Deformation and Fatigue Properties of Ultrafine Grain Size Materials: Current Status and Some Criteria for Improvement of the Fatigue Resistance

2000 ◽  
Vol 634 ◽  
Author(s):  
Haël Mughrabi ◽  
Heinz Werner Höppel
Keyword(s):  
Cyclic Deformation ◽  
Large Scale ◽  
Deformation Behaviour ◽  
Shear Banding ◽  
Friction Stress ◽  
Cyclic Softening ◽  
Current Status ◽  
Fatigue Properties ◽  
Ultrafine Grain ◽  
Angular Pressing

ABSTRACTIn this review, some general conclusions based on studies performed to date on fatigued materials of ultrafine grain (UFG) size produced by equal channel angular pressing (ECAP) are drawn, and open issues of current interest are defined. Important aspects addressed include the apparent discrepancy between improved fatigue strengths in Wöhler (S-N) plots as opposed to inferior fatigue strengths in Manson-Coffin plots, the clarification of the microstructural mechanisms of severe cyclic softening in conjunction with dynamic (local) grain/subgrain coarsening and damaging large-scale catastrophic shear banding. The important roles of the cyclic slip mode, the friction stress, the crystal structure and the temperature of cyclic deformation with respect to stable cyclic deformation behaviour are emphasized. Based on such considerations, criteria are formulated that must be observed, when designing ECAP-processed UFG-materials of superior fatigue strength.

Cyclic Deformation Behaviour and Fatigue Lives of Ultrafine-Grained Aluminium-Magnesium Alloys

2008 ◽  
Vol 584-586 ◽  
pp. 840-845 ◽  
Author(s):  
Heinz Werner Höppel ◽  
Johannes May ◽  
Matthias Göken
Keyword(s):  
Magnesium Alloys ◽  
Cyclic Deformation ◽  
Deformation Behaviour ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Cyclic Stability ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Mg Content ◽  
Influence Of Impurities

The fatigue behaviour of aluminium-magnesium alloys has been investigated in the recrystallized CG state and in an ultrafine-grained (UFG) state after equal channel angular pressing (ECAP). A strong improvement of the fatigue behaviour up to 12 ECAP passes has been found for an AlMg0.5 alloy. The results have been interpreted in consideration of the microstructure of the different states. Additionally, for an investigation of the influence of impurities on the cyclic stability of Aluminium, 3 different AlMg alloys with Magnesium contents of 0.5, 1, and 2 wt.-% have been compared. Total strain controlled fatigue tests have shown an improvement of the cyclic stability with increasing Mg content.

Effects of Equal Channel Angular Pressing and Heat Treatment on Low Cycle Fatigue Properties of 6005 Al Alloy

2008 ◽  
Vol 385-387 ◽  
pp. 721-724
Author(s):  
W.H. Kim ◽  
H.H. Cho ◽  
J.H. Cha ◽  
S.I. Kwun ◽  
Dong Hyuk Shin
Keyword(s):  
Heat Treatment ◽  
Equal Channel Angular Pressing ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Cyclic Softening ◽  
Fatigue Properties ◽  
Al Alloy ◽  
Cycle Fatigue ◽  
Angular Pressing ◽  
Aging Conditions

The effects of equal channel angular pressing (ECAP) and subsequent heat treatment on the low cycle fatigue properties of 6005 Al alloy were investigated. The ECAPed specimens showed cyclic softening, whereas the peak aged specimens showed cyclic hardening at all strain amplitudes. After ECAP, artificial aging was performed at 175°C to observe the change of the low cycle fatigue properties due to precipitation. The fatigue life and behavior of the unECAPed and ECAPed 6005 Al alloys were discussed in terms of the microstructural changes and aging conditions.

Recent Developments in the Downstream Processing of Phycobiliproteins from Algae: A Review

2021 ◽  
Vol 06 ◽  
Author(s):  
Ayekpam Chandralekha Devi ◽  
G. K. Hamsavi ◽  
Simran Sahota ◽  
Rochak Mittal ◽  
Hrishikesh A. Tavanandi ◽  
...  
Keyword(s):  
Cell Wall ◽  
Large Scale ◽  
Downstream Processing ◽  
Review Article ◽  
Current Status ◽  
Wall Structure ◽  
Scale Production ◽  
Cell Wall Disruption ◽  
Recent Developments ◽  
Macro Algae

Abstract: Algae (both micro and macro) have gained huge attention in the recent past for their high commercial value products. They are the source of various biomolecules of commercial applications ranging from nutraceuticals to fuels. Phycobiliproteins are one such high value low volume compounds which are mainly obtained from micro and macro algae. In order to tap the bioresource, a significant amount of work has been carried out for large scale production of algal biomass. However, work on downstream processing aspects of phycobiliproteins (PBPs) from algae is scarce, especially in case of macroalgae. There are several difficulties in cell wall disruption of both micro and macro algae because of their cell wall structure and compositions. At the same time, there are several challenges in the purification of phycobiliproteins. The current review article focuses on the recent developments in downstream processing of phycobiliproteins (mainly phycocyanins and phycoerythrins) from micro and macroalgae. The current status, the recent advancements and potential technologies (that are under development) are summarised in this review article besides providing future directions for the present research area.

Fracture and Fatigue Resistance of Ultrafine Grain CuCrZr Alloy Produced ECAP

2006 ◽  
Vol 503-504 ◽  
pp. 811-816 ◽  
Author(s):  
Alexei Vinogradov ◽  
Kazuo Kitagawa ◽  
V.I. Kopylov
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Stable Crack Growth ◽  
Ultrafine Grain ◽  
J Integral ◽  
Present Communication ◽  
Angular Pressing ◽  
Fatigue And Fracture ◽  
Anisotropy Of Mechanical Properties

Anisotropy of mechanical properties, fatigue and fracture resistance of precipitation hardened CuCrZr alloy ultrafine (UFG) grained by equal-channel angular pressing (ECAP) is in focus of the present communication. Fracture toughness was estimated in terms of J-integral and the fatigue crack growth rate was quantified. It was found that although the estimated JIC-value appeared lower than that reported in the literature for a reference alloy, the ductility, fracture and crack growth resistance remained satisfactory after ECAP while the tensile strength and fatigue limit improved considerably. The stable crack growth rate did not differ very much for ECAP and reference conventional CuCrZr and no remarkable anisotropy in the stable crack growth was noticed.

scholarly journals Fatigue Properties of AZ31B Magnesium Alloy Processed by Equal-Channel Angular Pressing

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1191
Author(s):  
Ryuichi Yamada ◽  
Shoichiro Yoshihara ◽  
Yasumi Ito
Keyword(s):  
Magnesium Alloy ◽  
Equal Channel Angular Pressing ◽  
Low Cycle Fatigue ◽  
Annealed Sample ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Angular Pressing ◽  
Fundamental Research ◽  
Number Of Cycles ◽  
Biodegradable Magnesium

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.

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