Study of tensile behaviour of thermally aged alloy D9 wrapper tubes of fast breeder reactor using acoustic emission

This work aims to investigate the effect of damage accumulation on the evolution of tensile properties due to prior ratcheting fatigue in as-received and artificially aged conditions of Al–Mg alloy (AA 5754). Uniaxial asymmetric stress controlled tests for various combinations of mean stress and stress amplitude are performed at room temperature. Progressive degradation in the mechanical properties of structures and machines subjected to cyclic loading during service period can affect the structural integrity. In view of this, ratcheting fatigue tests are interrupted at various life fractions for particular mean stress and stress amplitude followed by tensile tests to understand the damage evolution during ratcheting for both conditions of alloy. Also, the effect of mean stress and stress amplitude on the post ratcheting tensile behaviour is analysed by conducting the ratcheting tests up to 150 cycles. Cyclic hardening is exhibited in the initial cycles followed by saturation for both as-received and artificially aged alloy. Ratcheting strain increases with the increase in both mean stress and stress amplitude. Drastic changes in tensile properties are noticed with ratcheting fatigue damage evolution for both conditions of alloy. The evolution of tensile properties due to prior loading history such as ratcheting fatigue can provide fundamental understanding in the design of structural components.

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Monitoring Dynamic Recrystallisation in Bioresorbable Alloy Mg-1Zn-0.2Ca by Means of an In Situ Acoustic Emission Technique

Materials ◽

10.3390/ma15010328 ◽

2022 ◽

Vol 15 (1) ◽

pp. 328

Author(s):

Dmitry Merson ◽

Mikhail Linderov ◽

Alexander Brilevsky ◽

Alexey Danyuk ◽

Alexei Vinogradov

Keyword(s):

Acoustic Emission ◽

In Situ Monitoring ◽

Tensile Behaviour ◽

Median Frequency ◽

Fine Grained ◽

Specific Behaviour ◽

Wide Range ◽

Dynamic Recrystallisation ◽

First Time

The tensile behaviour of the biocompatible alloy Mg-1Zn-0.2Ca (in wt.%) in the fine-grained state, obtained by severe plastic deformation via multiaxial isothermal forging, has been investigated in a wide range of temperatures (20 ÷ 300) °C and strain rates (5 × 10−4 ÷ 2 × 10−2) s−1 with the measurements of acoustic emission (AE). The dependences of mechanical properties, including the yield stress, ultimate strength, ductility, and the strain-hardening rate, on the test temperature and strain rate, were obtained and discussed. It is shown for the first time that an acoustic emission method is an effective tool for in situ monitoring of the dynamic recrystallisation (DRX) process. The specific behaviour of the acoustic emission spectral density reflected by its median frequency as a function of strain at various temperatures can serve as an indicator of the DRX process’s completeness.

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Microstructural Characterization and Tensile Behaviour of a 3D Braided C/SiC Composite Fabricated by Chemical Vapour Infiltration

Advanced Composites Letters ◽

10.1177/096369350801700402 ◽

2008 ◽

Vol 17 (4) ◽

pp. 096369350801700 ◽

Cited By ~ 3

Author(s):

Yiqiang Wang ◽

Litong Zhang ◽

Laifei Cheng ◽

Junqiang Ma

Keyword(s):

Acoustic Emission ◽

Stress Analysis ◽

Computer Model ◽

Chemical Vapour ◽

Microstructural Characterization ◽

Interfacial Debonding ◽

Tensile Behaviour ◽

Nonlinear Behaviour ◽

Fibre Pullout ◽

Chemical Vapour Infiltration

The microstructure of a 3D C/SiC composite was characterized and the tensile behaviour was investigated in conjunction with acoustic emission (AE) technique. A computer model of the fibre architecture was generated for visualization and further stress analysis. The results show that the stress-strain curves exhibit mostly nonlinear behaviour with four distinguishable regions, which compare well with the AE characteristics. Microstructural observations reveal the superficial matrix cavities and large inter-bundle pores due to the 3D braiding fibre architecture. The failed specimens show ragged fracture surfaces and extensive fibre pullout, as well as interfacial debonding.

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