Effects of short-time heat treatment and subsequent chemical surface treatment on the mechanical properties, low-cycle fatigue behavior and corrosion resistance of a Ni–Ti (50.9at.% Ni) biomedical alloy wire used for the manufacture of stents

2011 ◽  
Vol 528 (3) ◽  
pp. 1864-1876 ◽  
Author(s):  
D. Vojtěch ◽  
M. Voděrová ◽  
J. Kubásek ◽  
P. Novák ◽  
P. Šedá ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Alloy Wire ◽  
Chemical Surface ◽  
Biomedical Alloy ◽  
Short Time ◽  
Subsequent Chemical

Evaluation of the Heat Treatment Role for Light Aluminum Alloys Subjected to Creep and Low Cycle Fatigue

2010 ◽  
Vol 638-642 ◽  
pp. 455-460 ◽  
Author(s):  
A. Rutecka ◽  
L. Dietrich ◽  
Zbigniew L. Kowalewski
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Low Cycle Fatigue ◽  
Numerical Models ◽  
Cyclic Hardening ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Lower Stress ◽  
Creep Tests ◽  
Different Temperatures

The AlSi8Cu3 and AlSi7MgCu0.5 cast aluminium alloys of different composition and heat treatment were investigated to verify their applicability as cylinder heads in the car engines [1]. Creep tests under the step-increased stresses at different temperatures, and low cycle fatigue (LCF) tests for a range of strain amplitudes and temperatures were carried out. The results exhibit a significant influence of the heat treatment on the mechanical properties of the AlSi8Cu3 and AlSi7MgCu0.5. An interesting fact is that the properties strongly depend on the type of quenching. Lower creep resistance (higher strain rates) and lower stress response during fatigue tests were observed for the air quenched materials in comparison to those in the water quenched. Cyclic hardening/softening were also observed during the LCF tests due to the heat treatment applied. The mechanical properties determined during the tests can be used to identify new constitutive equations and to verify existing numerical models.

scholarly journals Mechanical Properties and Very High Cycle Fatigue Behavior of Peak-Aged AA7021 Alloy

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1023 ◽  
Author(s):  
Byung-Hoon Lee ◽  
Sung-Woo Park ◽  
Soong-Keun Hyun ◽  
In-Sik Cho ◽  
Kyung-Taek Kim
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Solution Treated ◽  
Very High Cycle Fatigue ◽  
Peak Aged ◽  
Very High

The effect of heat treatment condition on non-Cu AA7021 alloy was investigated with respect to mechanical properties and very high cycle fatigue behavior. With a focus on the influence of heat treatment, AA7021 alloy was solution heat-treated at 470 °C for 4 h and aged at 124 °C. Comparing the results of solution-treated and peak-aged AA7021 alloy shows a significant increase in Vickers hardness and tensile strength. The hardness of AA7021 alloy was increased by 65% after aging treatment, and both tensile strength and yield strength were increased by 50~80 MPa in each case. In particular, this paper investigated the very high cycle fatigue behavior of AA7021 alloy with the ultrasonic fatigue testing method using a resonance frequency of 20 kHz. The fatigue results showed that the stress amplitude of peak-aged AA7021 alloy was about 50 MPa higher than the solution-treated alloy at the same fatigue cycles. Furthermore, it was confirmed that the size of the crack initiation site was larger after peak aging than after solution treatment.

Experimental Study of Viscoelastic Dampers under Large Deformation

2012 ◽  
Vol 166-169 ◽  
pp. 2226-2233 ◽  
Author(s):  
Gang Zhao ◽  
Peng Pan ◽  
Jia Ru Qian ◽  
Jin Song Lin
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Energy Dissipation ◽  
Low Cycle Fatigue ◽  
Loss Modulus ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Small Displacement ◽  
Loading Frequency ◽  
Cycle Fatigue

The paper presents an experimental study on a new type viscoelastic damper, which is expected to have better energy dissipation capability. Tests on the dampers’ mechanical properties, including shear storage modulus, shear loss modulus, and loss factor, were conducted using reduced scale specimens, and took strain amplitude, loading frequency and ambient temperature as test parameters. Aging tests, low cycle and high cycle fatigue tests were also conducted. Particularly, the low cycle fatigue behavior under a strain of 300% and the basic mechanical behavior under strains of 300%-420% were investigated. Test results suggest that the dependency of the mechanical properties on frequency and temperature is small, the energy dissipation capacity is stable for both large and small displacement, and the damper reaches a strain of 420% without failure.

scholarly journals Influence and Sensitivity of Temperature and Microstructure on the Fluctuation of Creep Properties in Ni-Base Superalloy

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4758
Author(s):  
Zhihao Yao ◽  
Biao Zhou ◽  
Kaijun Yao ◽  
Hongying Wang ◽  
Jianxin Dong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Residual Strain ◽  
Solution Heat Treatment ◽  
Low Cycle Fatigue ◽  
Fatigue Properties ◽  
Solution Temperature ◽  
Temperature Sensitive ◽  
Cycle Fatigue ◽  
Aero Engines

In this work, the sensitivity zone of microstructure and temperature for precipitation-strengthened nickel-based superalloys, used for turbine applications in aero-engines, has been firstly established. Heat treatment experiments with different solution temperatures were carried out. The microstructure evolution and creep residual strain sensitivity, low cycle fatigue properties, and tensile properties are analyzed, and the essential reason for the fluctuation of the mechanical properties of nickel-based superalloys was revealed. The main results obtained are as follows: following subsolvus solution heat treatment with a temperature of 1020 °C, samples have a high primary γ′I phase content, which is beneficial to low creep residual strain. Above the supersolvus solution temperature of 1040 °C, the creep residual strain value and low cycle fatigue performance fluctuate significantly. The essential reason for the dramatic fluctuation of performance is the presence of γ′ phases in different sizes and quantities, especially following the solution heat treatment in the temperature-sensitive zone of the γ′I phase, which is likely to cause huge fluctuations in the microstructure of tertiary γ′III phases. A zone of particular sensitivity in terms of temperature and microstructure for the γ′I phase is proposed. The range of suitable solution temperatures are discussed. In order to maintain stable mechanical properties without large fluctuations, the influence of the sensitivity within this temperature and microstructure zone on the γ′ phase should be considered.

An experimental investigation on low-cycle fatigue behavior of GO-NH2-reinforced epoxy adhesive

2020 ◽  
pp. 146442072097754
Author(s):  
Jamal Dabbagh ◽  
Bashir Behjat ◽  
Mojtaba Yazdani ◽  
Lucas FM da Silva
Keyword(s):  
Mechanical Properties ◽  
Graphene Oxide ◽  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Epoxy Adhesive ◽  
Cycle Fatigue ◽  
Hummers Method ◽  
Optimum Weight ◽  
Modified Hummers Method

In this study, the effect of adding functionalized aminated graphene oxide up to 0.3 wt% was experimentally investigated on the mechanical properties and fatigue behavior of an epoxy adhesive with intermediate toughness. Accordingly, graphene oxide was prepared by a modified Hummers method and was modified with 3-aminopropyltrimethoxysilane silane agent. Bulk samples were then prepared from neat and reinforced adhesive with different weight amounts of aminated graphene oxide. Dumbbell-shaped samples with a notch were used to limit displacement at break. The results showed the presence of 0.1 wt% and 0.3 wt% aminated graphene oxide nanoplatelets, as optimum weight percentages respectively for the mechanical properties and the fatigue life, improves the modulus of elasticity by 35% and the tensile strength by 44% as well as the fatigue life by about 72–241% under different cyclic loading conditions.

New Manufacturing Cycle to Improve the Life of Packing Cups for Hyper-Compressors

2012 ◽  
Author(s):  
Carmelo Maggi ◽  
Leonardo Tognarelli ◽  
Alessio Capanni ◽  
Jan Wojnar
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fem Analysis ◽  
Operating Conditions ◽  
Operating Pressure ◽  
Cycle Fatigue ◽  
Design Factor ◽  
Pressure Maximum ◽  
Critical Regions ◽  
Short Time

Hyper-compressors are subjected to very high operating pressure, maximum and fluctuating, strongly impacting design and life of all cylinder components. Components subjected to fatigue (both high cycle fatigue and low cycle fatigue) can experience a failure in a very short time that may cause large production losses. Packing cups proved to be one of the most critical cylinder components and the fatigue behavior of the packing cups subjected to alternating loads, due to the suction and discharge conditions, is their key design factor. A thorough study has been performed in order to increase the safety factors in all critical regions of the packing cups analyzing a new manufacturing cycle that allows optimizing the compressive pre-stresses on the lube oil parts due to the autofrettage procedure. The approach included a dedicated sensitivity FEM analysis of the autofrettage pressure to determine the correct residual stresses at the lube oil parts in order to keep them under compressive stress in operating conditions and Fracture Mechanics Calculations based on BSI7910 aimed at achieving a design able to survive with a threshold defect larger than the minimum detectable defect.

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