Fatigue life and fatigue-fracture toughness of certain magnesium alloys in air and in a vacuum

1979 ◽  
Vol 14 (4) ◽  
pp. 420-424
Author(s):  
N. M. Grinberg ◽  
V. A. Serdyuk ◽  
I. L. Ostapenko ◽  
T. I. Malinkina ◽  
A. S. Kamyshkov
Keyword(s):  
Fracture Toughness ◽  
Fatigue Life ◽  
Magnesium Alloys ◽  
Fatigue Fracture

scholarly journals Cyclic Deformation of Semi-solid Processed Magnesium Alloys

2021 ◽  
Author(s):  
Himesh Patel
Keyword(s):  
Fatigue Life ◽  
Magnesium Alloys ◽  
Strain Amplitude ◽  
Cyclic Deformation ◽  
Weight Ratio ◽  
Aging Treatment ◽  
Strain Ratio ◽  
Plastic Strain Amplitude ◽  
Total Strain Amplitude ◽  
Semi Solid

To improve fuel economy and reduce greenhouse gas emissions, magnesium alloys are being considered for automotive and aerospace applications because of their high strength-to-weight ratio. The objective of this thesis was to study monotonic and cyclic deformation behavior of two semi-solid processed (thixomolded) magnesium alloys, AZ91D and AM60B. The fatigue life of these thixomolded alloys was observed to be higher than that of their die cast counterparts. As the total strain amplitude increased, the stress amplitude and plastic strain amplitude increased, while the pseudoelastic modulus decreased. The change in the modulus was attributed to the nonlinear (pseudoelastic) behavior caused by twinning-detwinning during cyclic deformation. The fatigue life increased with decreasing strain ratio, and partial mean stress relaxation occurred mainly in the initial 10-20% of the fatigue life. The fatigue life of theAM60B alloy improved after solution or solution-aging treatment, and the monotonic strength increased by aging, while the thixomolded condition itself exhibited moderate monotonic strength and fatigue life.

scholarly journals Effects of Pre-Tensile Deformation on the Fatigue Fracture Behavior of Annealed 7005 Aluminum Alloy Plate

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 623
Author(s):  
Ni Tian ◽  
Zhen Feng ◽  
Xu Shi ◽  
Wenze Wang ◽  
Kun Liu ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Fatigue Fracture ◽  
Tensile Deformation ◽  
Thin Strip ◽  
Second Phase ◽  
Alloy Matrix ◽  
Alloy Plate ◽  
Dislocation Distribution ◽  
Aluminum Alloy Plate

In the present study, the fatigue life and fatigue fracture characteristics of annealed 7005 aluminum alloy plates subjected to different pre-tensile deformations were investigated. The results obtained upon increasing the pre-tensile deformation of the alloy plate to 20% revealed that the second-phase particles did not show any obvious changes, and that the thickness of the thin strip grain slightly decreased. The dislocation distribution in the alloy matrix varied significantly among the grains or within each grain as the dislocation density gradually increased with increasing pre-tensile deformation. Moreover, the fatigue performance of the annealed 7005 aluminum alloy plate was significantly improved by the pre-tensile deformation, and the alloy plate subjected to 20% pre-tensile deformation exhibited an optimal fatigue life of ~1.06 × 106 cycles, which was 5.7 times and 5.3 times that of the undeformed and 3% pre-stretched alloy plates, respectively. Two fatigue life plateaus were observed in the pre-tensile deformation ranges of 3–5% and 8–12%, which corresponded to heterogeneous dislocation distribution among various grains and within each grain, respectively. Moreover, two large leaps in the plot of the fatigue-life–pre-tensile-deformation curve were observed, corresponding to the pre-tensile deformation ranges of 5–8% and 16–20%, respectively.

scholarly journals PRELIMINARY INVESTIGATION OF BILLET PROCESSING ROUTE ON MICROSTRUCTURE, TEXTURE AND FATIGUE RESPONSE OF Ti834 FORGED DISC PRODUCTS

2020 ◽  
Vol 321 ◽  
pp. 11031
Author(s):  
B. Fernandez-Silva ◽  
B. P. Wynne ◽  
M. Jackson ◽  
M. Bodie ◽  
K. Fox
Keyword(s):  
Fatigue Life ◽  
Texture Analysis ◽  
Fatigue Fracture ◽  
Thermomechanical Processing ◽  
Preliminary Investigation ◽  
Processing Route ◽  
Bimodal Microstructure ◽  
Primary Alpha ◽  
Dwell Fatigue ◽  
Beta Matrix

Non-standard processing routes for the manufacture of industrial scale Ti834 billet have been undertaken to investigate their effect on macrozones in final forged product. Microstructure, texture and dwell fatigue fracture surfaces were characterised from forged disc samples fabricated from these new billets. All processing routes showed a bimodal microstructure consisting of 25pct of primary alpha grains in a transformed beta matrix. Texture analysis has revealed variations in the presence and size of macrozones with relatively weak textures. Quasi-cleavage facets were present in all dwell fatigue samples although the fatigue life was doubled for the sample whose thermomechanical processing has the highest imposed strain.

Analysis on the Fatigue Life of Asphalt Pavement under Traffic Flow Loads

2013 ◽  
Vol 361-363 ◽  
pp. 1727-1734
Author(s):  
Meng Qi Gao ◽  
Ping Ying Wang ◽  
He Ping Ding
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Fatigue Fracture ◽  
Fatigue Damage ◽  
Asphalt Pavement ◽  
Ansys Software ◽  
Element Analysis ◽  
Damage Area ◽  
Traffic Loads ◽  
Damage Rule

To study the fatigue life of asphalt pavement under traffic loads, a 3-D finite element analysis (FEA) Visio-elastic road model was established on the layered theory with ANSYS software. The fatigue damage was calculated with the maximum horizontal tensile strain of asphalt layer bottom based on the fatigue fracture mechanics, when single axis went across. Then the fatigue life was obtained after the fatigue damage occurred in some degree by the Miners linear cumulative damage rule. The results show that it taken 3.4 years when the damage area reached 10% of wheel path area, and 4.5years when reached 45%; while the calculated result was 5.5 years by axial-load conversion method. The analysis shows that the fatigue life of asphalt pavement calculated by fatigue fracture mechanics rule has more significance in practice.

Analysis on Low Cycle Fatigue Life and Fatigue Fracture Surface Morphology of TC25 Titanium Alloy

2016 ◽  
Vol 697 ◽  
pp. 652-657
Author(s):  
Rong Guo Zhao ◽  
Yi Yan ◽  
Yong Zhou Jiang ◽  
Xi Yan Luo ◽  
Qi Bang Li ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Fracture Surface ◽  
Crack Growth ◽  
Fatigue Fracture ◽  
Low Cycle Fatigue ◽  
Observation System ◽  
Cycle Fatigue ◽  
Stress Strain

At room temperature, the low cycle fatigue tests for smooth specimens of TC25 titanium alloy under various stress ranges are operated at a CSS280I-20w Electro Hydraulic Servo Universal Testing Machine with a microscopic observation system, and the low cycle fatigue lifetimes are measured. Based upon the analysis of stress-strain hysteresis loop of low cycle fatigue of TC25 titanium alloy, a simplified Manson-Coffin formula is derived according to both the experimental characteristics and the stress-strain constitutive model, the fatigue lifetimes are plotted against stress ranges, and a stress-fatigue life curve for TC25 titanium alloy is obtained by the linear regression analysis method. Finally, the fracture surface morphologies of TC25 specimens are investigated using a JSM-6360 Scanning Electron Microscopy, and the fatigue fracture mechanisms of low cycle fatigue are studied. It shows that the plastic deformations are mainly formed at the accelerated fracture stage, and various shear lips can be observed on the fracture surfaces, which demonstrates that the shear stress results in the final rupture of TC25 titanium alloy. During the fracture of low cycle fatigue, the cleavage nucleation leads to the formation of fatigue crack initiation region, the fatigue crack growth exhibits a mixed transgranular and intergranular crack growth mode, and in the final rupture region, the fracture surface of low cycle fatigue of TC25 titanium alloy appears as a typical semi-brittle fracture mode.

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