Study on the microstructural variation and fatigue performance of microplasma arc welded thin 316L sheet

2021 ◽  
pp. 146442072110620
Author(s):  
Dipankar Saha ◽  
Sukhomay Pal
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Complex Geometry ◽  
Sheet Material ◽  
Thin Sheet ◽  
Welding Process ◽  
Fatigue Performance ◽  
Cycle Fatigue ◽  
Delta Ferrite

Welding is a venerable and reliable fabricating technique to integrate materials into complex geometry desired for various industrial applications. However, localized heat concentration leading to microstructural variations can deteriorate the fatigue life of welded components. The present study explains tensile and high cycle fatigue performance of microplasma arc welded 316L SS thin sheet (0.5 mm thickness) material. The square butt joint configuration with a single pass weld was achieved for 316L SS similar sheet material. The skeletal and lathy delta-ferrite-austenitic structures were observed in the fusion zone (FZ) due to non-equilibrium solidification, which is attributed to the different thermal cycle behaviour of the FZ. This morphology is explained by the pseudo phase diagram and the Schaeffler diagram of SS material. The tensile test showed that the microplasma arc welding process achieved a joining efficiency of 93%. The high cycle fatigue performance of welded specimens was analysed at different alternating stress amplitude. The presence of a dense delta ferrite phase in the austenitic matrix is responsible for fatigue failure of the welded specimen. However, the development of deformation-induced martensite in the crack initiation site promotes fatigue life. The crack initiation, propagation, and sudden failure site were investigated to explain the fatigue fracture behaviour.

scholarly journals The effect of decarburization on the fatigue life of overhead line hardware

2021 ◽  
Vol 121 (10) ◽  
pp. 1-6
Author(s):  
J. Calitz ◽  
S. Kok ◽  
D. Delport
Keyword(s):  
Fatigue Life ◽  
Tensile Properties ◽  
High Cycle Fatigue ◽  
Fatigue Performance ◽  
Span Length ◽  
Cycle Fatigue ◽  
Overhead Line ◽  
Fatigue Load ◽  
Homogeneous Microstructure ◽  
Overhead Power Line

Altering the microstructure in order to improve the tensile properties of bow shackles resulted in inconsistency in the fatigue performance. This raises the question whether the inconsistency in fatigue life can be attributed to microstructural changes along the profile of the shackle or to decarburization at the surface. Bow shackles forged from 080M40 (EN8) material were subjected to different heat treatments in order to alter the microstructure. The shackles were subjected to five different fatigue load cases, which represented typical loads experienced at termination points for an overhead power line with a span length of 400 m, with changes in conductor type, configuration, wind, and ice loading. Although the change in microstructure does improve both the tensile and fatigue performance, we found that the depth of the decarburization layer has a greater effect on the high cycle fatigue life of bow shackles than the non-homogeneous microstructure.

scholarly journals Research on the Fatigue Performance of TC6 Compressor Blade under the CCF Effect

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Zhang Yakui ◽  
Guo Shuxiang
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Compressor Blade ◽  
Fatigue Performance ◽  
Cycle Fatigue ◽  
Test Rig ◽  
Source Characteristics ◽  
Fracture Appearance ◽  
Fatigue Life Reduction

This paper studied the influence of high and low combined fatigue (CCF) on compressor blade fatigue performance. We investigated the coupling between low cycle fatigue (LCF) loading from centrifugal force with high cycle fatigue (HCF) loading from vibration and determined the blade disc vibration frequency using static analysis at maximum rotational speed. We designed and constructed a combined fatigue test rig, and CCF tests were performed on a TC6 compressor blade to analyze fatigue life characteristics. Results showed that CCF could significantly shorten blade life compared with pure LCF and that larger HCF caused more significant fatigue life reduction. Fatigue source characteristics and CCF fracture appearance were observed and analyzed using a scanning electron microscope (SEM).

Enhancing Fatigue Properties of Nanostructured Metals and Alloys

2007 ◽  
Vol 29-30 ◽  
pp. 117-122 ◽  
Author(s):  
Terry C. Lowe
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Computational Methods ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Metals And Alloys ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Nanostructured Metals ◽  
Improve Fatigue

Recent research on the fatigue properties of nanostructured metals and alloys has shown that they generally possess superior high cycle fatigue performance due largely to improved resistance to crack initiation. However, this advantage is not consistent for all nanostructured metals, nor does it extend to low cycle fatigue. Since nanostructures are designed and controlled at the approximately the same size scale as the defects that influence crack initiation attention to preexisting nanoscale defects is critical for enhancing fatigue life. This paper builds on the state of knowledge of fatigue in nanostructured metals and proposes an approach to understand and improve fatigue life using existing experimental and computational methods for nanostructure design.

The Improvement of High Cycle Fatigue Properties of AC4CH Alloy with Shot Peening Treatment

2005 ◽  
Vol 297-300 ◽  
pp. 1919-1924
Author(s):  
Kiyotaka Masaki ◽  
Yasuo Ochi ◽  
Takashi Matsumura
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Shot Peening ◽  
High Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Crack Propagation Rate ◽  
Fatigue Properties ◽  
Fatigue Crack Propagation Rate ◽  
Cycle Fatigue

In order to investigate the effect of SP treatment on the high cycle fatigue properties such as fatigue strength, crack initiation and propagation behaviors, rotating bending fatigue tests on shot-peening (SP) treated AC4CH aluminum alloy were carried out. The fatigue properties of the SP-treated material were compared with fatigue properties of the non-peened material, the hot isostatic pressure (HIP) treated material and the semi-liquid (SL) die casting material. the main conclusions obtained were, (1) The fatigue properties of SP-treated material is most excellent in all materials. (2) The fatigue life property of AC4CH alloys is significantly affected by fatigue crack initiation behavior. The reason why the SP-treated material has longer fatigue life than those of other material is that it has no cast defects near the surface by the effect of SP treatment. (3) The reason of fatigue life improvement by SP treatment is decrease of fatigue crack propagation rate.

The Top 10 Influential Articles in Very High Cycle Fatigue

2015 ◽  
Vol 664 ◽  
pp. 22-30
Author(s):  
Yong Jie Liu ◽  
Muhammad Kashif Khan ◽  
Qing Yuan Wang
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Web Of Science ◽  
Cycle Fatigue ◽  
Science Data ◽  
Specialty Area ◽  
Very High Cycle Fatigue ◽  
Very High

The top 10 most influential articles in Very high cycle fatigue (VHCF) have been indentified from web of science data. The attributes of the top 10 papers have been discussed. It was found that specialty area of fatigue called as “VHCF” is an emerging field. The most cited papers discussed the two the fatigue crack mechanism in fatigue. It was found that crack initiation shifts from surface to subsurface if the material beyond 107 cycles. There are some models which can predict the fatigue life of the material however the exact estimation is still challenging. Hence, it was found that still further efforts are required in the field to accurately understand the VHCF behavior.

Effect of Aluminized Coating on Combined Low and High Cycle Fatigue Life of Turbine Blade at Elevated Temperature

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Cao Chen ◽  
Xiaojun Yan ◽  
Xiaoyong Zhang ◽  
Yingsong Zhang ◽  
Min Gui ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Elevated Temperature ◽  
Crack Initiation ◽  
Turbine Blade ◽  
High Cycle Fatigue ◽  
Turbine Blades ◽  
Cycle Fatigue ◽  
Σ Phase ◽  
Initiation And Propagation ◽  
Crack Initiation Life

Some cracks were detected on the fir-tree root of turbine blade in an in-service aero-engine, and the aluminized coating was considered to be the main cause of these cracks. To study the effect of aluminized coating on fatigue life of turbine blade, the combined low and high cycle fatigue (CCF) tests are carried out at elevated temperature on both aluminized and untreated turbine blades. Probability analysis of test data is conducted and the result indicates that the median life is decreased by 62.2% due to the effect of the aluminized coating. Further study on the mechanism of crack initiation and propagation has been conducted based on fractography and cross section morphology analysis by using scanning electron microscope (SEM), and the results indicate: (1) The aluminized coating consists of two layers, of which the inner layer is considered to contain the σ phase and it reduces the resistance to fatigue of blade. (2) Many cavities are found in the inner layer of aluminized coating, which lead to the initiation of cracks and result in the reduction of crack initiation life. (3) The marker band widths of aluminized and untreated blade are very close, which indicated the aluminized coating may have no effect on the crack propagation life of the blade.

Fatigue Performance of Copper Alloys in Seawater Environment

2013 ◽  
Vol 577-578 ◽  
pp. 261-264
Author(s):  
Jochen Aufrecht ◽  
Andrew Drach ◽  
Adolf Grohbauer ◽  
Uwe Hofmann ◽  
Stefan Theobald ◽  
...  
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Copper Alloys ◽  
Fatigue Performance ◽  
Natural Seawater ◽  
Rectangular Plates ◽  
Cycle Fatigue ◽  
Seawater Environment

Corrosion fatigue performance of two copper alloys (admiralty brass and cupronickel 90/10) is investigated by conducting fatigue tests in artificial seawater. Two different experimental setups are developed and used: immersed rotating beam bending of round wires and immersed flexural cycling of rectangular plates. For the second setup, two sets of specimens are used: as-manufactured and after 1-year exposure to natural seawater in North Atlantic. In addition, the fatigue performance is compared between the dry and immersed tests. It is observed that the fatigue life of copper alloys in seawater environment depends on their composition and manufacturing parameters. Immersion in seawater does not affect low-cycle fatigue, however, high-cycle fatigue behavior shows significant differences. It is also observed that one-year preliminary exposure to natural seawater (stress-free corrosion) results in up to three times reduction of fatigue life at stress amplitudes corresponding to high-cycle fatigue.

scholarly journals Influence of Strain Gradient on Fatigue Life of Carbon Steel for Pressure Vessels in Low-Cycle and High-Cycle Fatigue Regimes

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 445
Author(s):  
Tomoyuki Fujii ◽  
Muhamad Safwan Bin Muhamad Azmi ◽  
Keiichiro Tohgo ◽  
Yoshinobu Shimamura
Keyword(s):  
Fatigue Life ◽  
Carbon Steel ◽  
Crack Initiation ◽  
Strain Gradient ◽  
High Cycle Fatigue ◽  
Pressure Vessels ◽  
Cycle Fatigue ◽  
Total Failure ◽  
Crack Initiation Life ◽  
Failure Life

This paper discusses how the strain gradient influences the fatigue life of carbon steel in the low-cycle and high-cycle fatigue regimes. To obtain fatigue data under different strain distributions, cyclic alternating bending tests using specimens with different thicknesses and cyclic tension–compression tests were conducted on carbon steel for pressure vessels (SPV235). The crack initiation life and total failure life were evaluated via the strain-based approach. The experimental results showed that the crack initiation life became short with decreasing strain gradient from 102 to 106 cycles in fatigue life. On the other hand, the influence of the strain gradient on the total failure life was different from that on the crack initiation life: although the total failure life of the specimen subjected to cyclic tension–compression was also the shortest, the strain gradient did not affect the total failure life of the specimen subjected to cyclic bending from 102 to 106 cycles in fatigue life. This was because the crack propagation life became longer in a thicker specimen. Hence, these experimental results implied that the fatigue crack initiation life could be characterized by not only strain but also the strain gradient in the low-cycle and high-cycle fatigue regimes.

scholarly journals Defect induced cracking and modeling of fatigue strength for an additively manufactured Ti-6Al-4V alloy in very high cycle fatigue regime

2021 ◽  
Author(s):  
Weiqian Chi ◽  
Wenjing Wang ◽  
Chengqi Sun
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Crack Initiation ◽  
Surface Defect ◽  
High Cycle Fatigue ◽  
Projection Area ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Artificial Surface ◽  
Very High

Additively manufactured (AM) alloy usually inevitably contains defects during manufacturing processor in service. Defects, as a harmful factor, could significantly reduce the fatigue performance of materials. This paper shows that the location and introduced form of defects play an important role in high cycle and very high cycle fatigue (VHCF) behavior of selective laser melting Ti-6Al-4V alloy. The fatigue life descends linearly with stress amplitude for interior defect induced failure. While for artificial surface defect induced failure, the fatigue life descends at first, and then exhibits a plateau region feature. We also observed competition of interior crack initiation with fine granular area feature in VHCF regime. The paper indicates that only the size or the stress intensity factor range of the defect is not an appropriate parameter describing the effect of defect on the fatigue crack initiation. Finally, the effect of artificial surface defect on high cycle and VHCF strength is modeled, i.e. the fatigue strength  σ, fatigue life  N and defect size ( area)  (square root of projection area of defect perpendicular to principal stress direction) is expressed as  σ= CN( area) for  N0 and  σ= CN ( area) for  N≥N , where  C,  a and  n are constants, N  is the number of cycles at the knee point.

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