Micro-cantilever fatigue tests using multi-directionally forged  and fine-grained AZ61 magnesium alloy

Fatigue Property of an Extruded AZ61 Magnesium Alloy with the Processing Layer Introduced by Machining was Investigated. Rotating Bending Fatigue Tests were Carried out with the Specimen with and without the Processing Layer. According to Results of the Fatigue Tests, Fatigue Life Significantly Increased by Introducing the Processing Layer to the Specimen Surface. Fatigue Crack Initiation and Propagation Behaviors were Observed by Replication Technique during the Fatigue Test. Fatigue Crack Initiation Life of the Specimen with the Processing Layer was Slightly Longer than that of the Specimen without the Processing Layer. Higher Fatigue Crack Growth Resistance was also Observed when the Fatigue Crack was Growing in the Processing Layer in the Specimen with the Processing Layer. the Longer Fatigue Life Observed in the Fatigue Test in the Specimen with the Processing Layer could be Mainly due to the Higher Crack Growth Resistance. it is Speculated that the Fatigue Strength can be Controlled by Change in Condition of Machining Process. it could be Effective way in Industry to Improved Fatigue Strength only by the Cutting Process without Additional Surface Treatment Process.

Download Full-text

Superplasticity in fine-grained AZ61 magnesium alloy

Metals and Materials ◽

10.1007/bf03028220 ◽

2000 ◽

Vol 6 (3) ◽

pp. 255-259 ◽

Cited By ~ 6

Author(s):

W. J. Kim ◽

S. W. Chung

Keyword(s):

Magnesium Alloy ◽

Fine Grained ◽

Az61 Magnesium Alloy

Download Full-text

Superplastic gas pressure forming of fine-grained AZ61 magnesium alloy sheet

Materials Science and Engineering A ◽

10.1016/j.msea.2003.08.125 ◽

2004 ◽

Vol 372 (1-2) ◽

pp. 15-20 ◽

Cited By ~ 27

Author(s):

S.W. Chung ◽

K. Higashi ◽

W.J. Kim

Keyword(s):

Magnesium Alloy ◽

Alloy Sheet ◽

Gas Pressure ◽

Magnesium Alloy Sheet ◽

Fine Grained ◽

Az61 Magnesium Alloy

Download Full-text

Fracture behavior of twin induced ultra-fine grained ZK61 magnesium alloy under high strain rate compression

Journal of Materials Research and Technology ◽

10.1016/j.jmrt.2019.06.018 ◽

2019 ◽

Vol 8 (4) ◽

pp. 3475-3486 ◽

Cited By ~ 15

Author(s):

Abdul Malik ◽

Wang Yangwei ◽

Cheng Huanwu ◽

Muhammad Abubaker Khan ◽

Faisal Nazeer ◽

...

Keyword(s):

Magnesium Alloy ◽

High Strain Rate ◽

Strain Rate ◽

Fracture Behavior ◽

High Strain ◽

Fine Grained ◽

Strain Rate Compression

Download Full-text

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

Metals ◽

10.3390/met11081191 ◽

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.

Download Full-text

Effect of micro-notches on fatigue strength of electrodeposited nanocrystalline nickel thin films

MATEC Web of Conferences ◽

10.1051/matecconf/201816504011 ◽

2018 ◽

Vol 165 ◽

pp. 04011

Author(s):

Keisuke Tanaka ◽

Yuta Murase ◽

Hirohisa Kimachi

Keyword(s):

Thin Films ◽

Fatigue Strength ◽

Fatigue Limit ◽

Stress Ratio ◽

Fatigue Crack Initiation ◽

Fatigue Tests ◽

Fine Grained ◽

Nickel Thin Films ◽

Nano Crystalline ◽

Fictitious Crack

The effect of micro-notches on the fatigue strength of nickel thin films was studied. Two types of thin films with 10 μm thickness were produced by electrodeposition using sulfamate solution without and with brightener: ultra-fine grained film (UFG) with the grain size of 384 nm and nano-crystalline grained film (NCG) with that of 17 nm. Micro-sized notches introduced by FIB had the width of 2 μm and various depths from 8 to 150μm. Fatigue tests were conducted under the stress ratio of 0.1. The fatigue strength decreased with increasing depth of notches. NCG had much higher strength than UFG compared at the same notch depth. Notches as small as 8μm did reduce the fatigue strength of both UFG and NCG. The fatigue limit was controlled by the initiation of cracks and no non-propagating crack was observed in specimens fatigued below the fatigue limit. A model of fictitious crack successfully predicted the reduction of the fatigue limit due to micro-notches. The characteristic crack length of NCG was much smaller than the UFG, while the fatigue strength of defect-free NCG was larger than that of UFG. SEM observation of fracture surfaces was conducted to reveal micromechanisms of fatigue crack initiation.

Download Full-text