Fatigue behavior of nanoscale Mo/W multilayers on flexible substrates

MRS Advances ◽  
2019 ◽  
Vol 4 (43) ◽  
pp. 2309-2317
Author(s):  
Fang Wang ◽  
Xue-Mei Luo ◽  
Dong Wang ◽  
Peter Schaaf ◽  
Guang-Ping Zhang
Keyword(s):  
Fatigue Resistance ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Properties ◽  
Individual Layer ◽  
Out Of Plane ◽  
Inclination Angles ◽  
Plane Direction ◽  
Columnar Grain ◽  
20 Nm

ABSTRACTFatigue properties of Mo/W multilayers with individual layer thickness (λ) of 5, 20, 50 and 100 nm on flexible polyimide substrates were investigated. The experimental results show that the fatigue resistance increases with decreasing λ from 100 nm to 20 nm, and reaches the maximum at λ=20 nm, and then decreases when further decreasing λ. Fatigue cracks of Mo/W multilayers with different λ were found to propagate along columnar grain boundary in the out-of-plane direction and along the boundary of cluster structures. The enhanced fatigue resistance is attributed to the larger cluster inclination angles and the more tortuous in-plane cracking paths.

scholarly journals Quantitative Analysis of Inclusion Engineering on the Fatigue Property Improvement of Bearing Steel

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 476 ◽  
Author(s):  
Chao Gu ◽  
Min Wang ◽  
Yanping Bao ◽  
Fuming Wang ◽  
Junhe Lian
Keyword(s):  
Fatigue Life ◽  
Quantitative Analysis ◽  
Critical Size ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Property ◽  
Bearing Steel ◽  
Fatigue Properties ◽  
Bearing Steels ◽  
Inclusion Distribution

The fatigue property is significantly affected by the inner inclusions in steel. Due to the inhomogeneity of inclusion distribution in the micro-scale, it is not straightforward to quantify the effect of inclusions on fatigue behavior. Various investigations have been performed to correlate the inclusion characteristics, such as inclusion fraction, size, and composition, with fatigue life. However, these studies are generally based on vast types of steels and even for a similar steel grade, the alloy concept and microstructure information can still be of non-negligible difference. For a quantitative analysis of the fatigue life improvement with respect to the inclusion engineering, a systematic and carefully designed study is still needed to explore the engineering dimensions of inclusions. Therefore, in this study, three types of bearing steels with inclusions of the same types, but different sizes and amounts, were produced with 50 kg hot state experiments. The following forging and heat treatment procedures were kept consistent to ensure that the only controlled variable is inclusion. The fatigue properties were compared and the inclusions that triggered the fatigue cracks were analyzed to deduce the critical sizes of inclusions in terms of fatigue failure. The results show that the critical sizes of different inclusion types vary in bearing steels. The critical size of the spinel is 8.5 μm and the critical size of the calcium aluminate is 13.5 μm under the fatigue stress of 1200 MPa. In addition, with the increase of the cleanliness of bearing steels, the improvement of fatigue properties will reach saturation. Under this condition, further increasing of the cleanliness of the bearing steel will not contribute to the improvement of fatigue property for the investigated alloy and process design.

scholarly journals Fatigue Behavior of Non-Optimized Laser-Cut Medical Grade Ti-6Al-4V-ELI Sheets and the Effects of Mechanical Post-Processing

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 843 ◽  
Author(s):  
André Reck ◽  
André Till Zeuner ◽  
Martina Zimmermann
Keyword(s):  
Surface Roughness ◽  
Fatigue Strength ◽  
Surface Quality ◽  
Laser Cutting ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Surface Condition ◽  
Mechanical Polishing ◽  
Fatigue Properties ◽  
Post Processing

The study presented investigates the fatigue strength of the (α+β) Ti-6Al-4V-ELI titanium alloy processed by laser cutting with and without mechanical post-processing. The surface quality and possible notch effects as a consequence of non-optimized intermediate cutting parameters are characterized and evaluated. The microstructural changes in the heat-affected zone (HAZ) are documented in detail and compared to samples with a mechanically post-processed (barrel grinding, mechanical polishing) surface condition. The obtained results show a significant increase (≈50%) in fatigue strength due to mechanical post-processing correlating with decreased surface roughness and minimized notch effects when compared to the surface quality of the non-optimized laser cutting. The martensitic α’-phase is detected in the HAZ with the formation of distinctive zones compared to the initial equiaxial α+β microstructure. The HAZ could be removed up to 50% by means of barrel grinding and up to 100% through mechanical polishing. A fracture analysis revealed that the fatigue cracks always initiate on the laser-cut edges in the as-cut surface condition, which could be assigned to an irregular macro and micro-notch relief. However, the typical characteristics of the non-optimized laser cutting process (melting drops and significant higher surface roughness) lead to early fatigue failure. The fatigue cracks solely started from the micro-notches of the surface relief and not from the dross. As a consequence, the fatigue properties are dominated by these notches, which lead to significant scatter, as well as decreased fatigue strength compared to the surface conditions with mechanical finishing and better surface quality. With optimized laser-cutting conditions, HAZ will be minimized, and surface roughness strongly decreased, which will lead to significantly improved fatigue strength.

Effect of Bias Voltage on Fatigue Behavior of CrN Film Deposited on Ti-6Al-4V Alloy

2008 ◽  
Author(s):  
Md. Shamimur Rahman ◽  
Daisuke Yonekura ◽  
Takeshi Katsuma ◽  
Ri-Ichi Murakami
Keyword(s):  
Fatigue Life ◽  
Bias Voltage ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Substrate Surface ◽  
Film Deposition ◽  
Fatigue Properties ◽  
Ion Plating ◽  
Coated Substrate ◽  
Coating Composite

PVD technique incorporating CrN coating was applied to the titanium alloy (Ti-6Al-4V) and its effects on the fatigue life and fatigue strength were studied in this paper to explore the fatigue behavior of Ti-6Al-4V specimens. A CrN film deposited by arc ion plating (AIP) improved the mechanical properties; specially hardness and fatigue life of Ti-6Al-4V specimens. The properties were studied using XRD, hardness and fatigue testers. The fatigue life of CrN-coated Ti-6Al-4V specimens was improved significantly compared to those of uncoated specimens. The enhanced fatigue life can be attributed to the improved hardness of CrN film due to change of bias voltage during the film deposition. The initiation of fatigue cracks is likely to be retarded by the presence of hard and strong layers on the substrate surface. It has been determined that the fatigue fracture of the substrate-coating composite is dominated by the fracture of the CrN film since fatigue cracks have been observed to form first at the surface of the film and subsequently to propagate towards the substrate. It has also been concluded that the increase in fatigue properties of the coated substrate is associated mainly with the changing of bias voltage during the coating observed in most of the maximum alternating stress range explored in this work.

Fatigue Behaviour of Ti-6Al-4V Alloy in Vacuum and at Low Temperature

2008 ◽  
Vol 41-42 ◽  
pp. 83-90 ◽  
Author(s):  
J.H. Zuo ◽  
Z.G. Wang ◽  
En Hou Han
Keyword(s):  
Low Temperature ◽  
Fatigue Fracture ◽  
Room Temperature ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Sample Surface ◽  
Fatigue Behaviour ◽  
Fatigue Properties ◽  
Fatigue Fracture Surface ◽  
Cracks Propagation

Investigations have been conducted on the fatigue behavior of Ti-6Al-4V alloy with the bimodal microstructure in air at room temperature, in vacuum at room temperature and in vacuum at low temperature (100K), respectively. The results show that the fatigue life of this alloy is longer in vacuum and/or at low temperature than that in air at room temperature. The combination of vacuum and low temperature can much improve the fatigue properties of this alloy because of their purifying effect on fatigue cracks propagation. SEM observation of fatigue fracture surface indicates that all the fatigue cracks initiate in the sample surface when Nf ≦106 cycles. The above three testing conditions lead to different modes of fatigue crack propagation and therefore much different morphology of fatigue fracture.

Effect of Fiber Volume Fraction on Low Cycle Fatigue Behavior of Al2O3f/Al-Si Composites

2012 ◽  
Vol 268-270 ◽  
pp. 87-91
Author(s):  
Jian Jun Cui ◽  
Bing Chao Li ◽  
Guo Hua Zhang ◽  
Jian Xin Zhang ◽  
Zuo Shan Wei ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Short Fibers ◽  
Fiber Volume ◽  
Large Size

The tensile and low cycle fatigue tests were carried out on alumina short fibers reinforced Al-Si piston alloy composites (Al-Si MMCs). Three Al-Si MMCs reinforced with 10, 17 and 25 vol.% of alumina short fibers were prepared to investigate the effects of volume fraction on tensile and low cycle fatigue properties at room temperature (RT) and 350°C. The results showed that the tensile strength decreased with the increasing of volume fraction of fibers at RT and was slight different at 350°C. Among the three MMCs, the 17%-MMCs showed highest stress level under the low cycle fatigue tests. The fatigue cracks were usually initiated from the clustered and large size fibers near the surface of specimen, propagated along the fiber/matrix interface at RT and grew rapidly by means of broken the fibers at 350°C.

Effect of Fiber Volume Fraction on Low Cycle Fatigue Behavior of Al2O3f/Al-Si Composites

2012 ◽  
Vol 622-623 ◽  
pp. 1340-1344
Author(s):  
Jian Jun Cui ◽  
Bing Chao Li ◽  
Guo Hua Zhang ◽  
Jian Xin Zhang ◽  
Zuo Shan Wei ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Short Fibers ◽  
Fiber Volume ◽  
Large Size

The tensile and low cycle fatigue tests were carried out on alumina short fibers reinforced Al-Si piston alloy composites (Al-Si MMCs). Three Al-Si MMCs reinforced with 10, 17 and 25 vol.% of alumina short fibers were prepared to investigate the effects of volume fraction on tensile and low cycle fatigue properties at room temperature (RT) and 350°C. The results showed that the tensile strength decreased with the increasing of volume fraction of fibers at RT and was slight different at 350°C. Among the three MMCs, the 17%-MMCs showed highest stress level under the low cycle fatigue tests. The fatigue cracks were usually initiated from the clustered and large size fibers near the surface of specimen, propagated along the fiber/matrix interface at RT and grew rapidly by means of broken the fibers at 350°C.

Effect of Frequency on the Fatigue Behavior of IN718 Superalloy

2017 ◽  
Vol 1142 ◽  
pp. 23-30 ◽  
Author(s):  
Jin Hui Du ◽  
Xu Dong Lu ◽  
Qun Deng
Keyword(s):  
Grain Size ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Low Frequency ◽  
Initiation Site ◽  
Fatigue Properties ◽  
Crack Initiation Site

IN718 alloy possesses excellent mechanical properties at high temperatures, good process ability, therefore, it has been widely used in aero engine turbine disks, compressor disks, and power turbine shafts (i.e., rotating components). The fatigue properties of the alloy are a key factor that determines the safety and reliability of the engine. In this paper, the fatigue properties of IN718 alloy are investigated under low-and middle-frequency conditions at 600 °C and 455 °C, the initiation of fatigue cracks, and the relation between fatigue life and grain size are discussed. The results show that the carbides response as a crack initiation site at low-frequency fatigue condition (1 Hz), and string-type or heap-type carbides distribution promotes crack propagation and shortens fatigue life, the twin boundaries in large grains are act as a crack initiation site at middle-frequency fatigue condition (10 Hz). The grain size is smaller, and the low cycle fatigue properties of the alloy are better.

Fatigue Behavior of Type 316L Stainless Steel Coated with Plasma-Sprayed Alumina in Corrosive Environment

1998 ◽  
Author(s):  
H. Kisuki ◽  
M. Sugano ◽  
T. Oshima ◽  
Y. Nasu ◽  
K. Okazaki ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Fatigue Strength ◽  
Plasma Spraying ◽  
Early Stage ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Properties ◽  
Crack Growth Behavior ◽  
Grit Blasting ◽  
Plasma Sprayed

Abstract Fatigue properties of the Al2O3 plasma-sprayed SUS316L stainless steel rod specimens coated on different spraying conditions have been studied in a physiological saline solution (0.9 % NaCl solution) to evaluate the potential of surgical implant application. Fatigue tests were conducted in push-pull loading at the stress ratio of R = -1, and frequency of 2 Hz. Microstructure related with fatigue damage was examined by SEM and TEM. The fatigue strength of Al2O3 plasma-sprayed metals significantly depended on spraying conditions: the effects of spraying on fatigue strength decreased with increasing the applied stress amplitude. As-blasted specimens were higher in fatigue strength than Al2O3 plasma-sprayed specimens. It was found that the plasma spraying had significant effects on fatigue crack growth behavior in the early stage of crack propagation. Fatigue cracks preferentially originated from dents that had been caused on the substrata metal surface subjected to grit-blasting. These results are discussed with both the compressive residual stresses due to the grit blasting which was carried out prior to plasma spraying and the corrosion-resistance of the alumina deposit.

High-Temperature Low-Cycle Fatigue Behavior of 625 Nickel-Base Superalloy Welding Joint

2014 ◽  
Vol 618 ◽  
pp. 120-124
Author(s):  
Yuan Yuan Wang ◽  
Bao Sen Wang ◽  
Li Jia Chen
Keyword(s):  
High Temperature ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Properties ◽  
Nickel Base Superalloy ◽  
Cycle Fatigue ◽  
Welding Joint ◽  
Nickel Base ◽  
Base Superalloy

High temperature low cycle fatigue properties and fracture behavior of Inconel 625 nickel-base superalloy welding joint at 760oC were investigated under fully reversed total strain-controlled mode. The fatigue life and cyclic stress-strain data were analyzed to determine the individual strain fatigue parameters. It is noted that the welding joint exhibits the cyclic strain hardening and stability. The fatigue cracks initiate predominantly on the free surface of fatigue specimens and propagate in an intergranular mode or a mixed transgranular and intergranular mode.

Fatigue Properties of Rapidly Solidified Mg-6Zn-1Y-0.6Ce-0.6Zr Alloy Processed by Reciprocating Extrusion

2010 ◽  
Vol 667-669 ◽  
pp. 1027-1032
Author(s):  
Zhong Ming Zhang ◽  
Chun Jie Xu ◽  
Ting Wang ◽  
Lin Yang
Keyword(s):  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Curve ◽  
Fatigue Properties ◽  
Tension Stress ◽  
Dispersion Strengthening ◽  
Axial Tension ◽  
High Fatigue ◽  
Rapidly Solidified ◽  
Reciprocating Extrusion

The ribbons of rapidly solidified Mg-6wt%Zn-1wt%Y-0.6wt%Ce-0.6wt%Zr alloy were reciprocatingly extruded and forward extruded into dense bar material. Room-temperature fatigue behavior of the alloy was tested in axial tension-tension stress condition. The fracture morphologies of the alloy after fatigue were observed by SEM. The results show that the fatigue limit is 159.2MPa with 106 cycles when the load frequency was 10Hz. The S-N curve of the alloy can be regarded as Type Ⅱ fatigue curve. The fatigue cracks originate from surface or subsurface of the fatigue specimens generally. The second phases or inclusions in these areas were prone to be the crack sources. The high fatigue properties of the alloy can be attributed to grain refinement strengthening and dispersion strengthening resulted from rapid solidification and reciprocating extrusion.

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