scholarly journals Comparison of High-Temperature Compression and Compression-Compression Fatigue Behavior of Magnesium Alloys DieMag422 and AE42

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 497 ◽  
Author(s):  
Mirko Teschke ◽  
Alexander Koch ◽  
Frank Walther
Keyword(s):  
Magnesium Alloys ◽  
Elevated Temperatures ◽  
Fatigue Behavior ◽  
Weight Ratio ◽  
High Strength ◽  
Fatigue Tests ◽  
Fracture Mechanisms ◽  
Compression Tests ◽  
Computed Tomographic ◽  
Tensile Fatigue

Due to their high strength-to-weight-ratio, magnesium alloys are very attractive for use in automotive engineering. For application at elevated temperatures, the alloys must be creep-resistant. Therefore, the influence of the operating temperature on the material properties under quasistatic and cyclic load has to be understood. A previous study investigated tensile-tensile fatigue behavior of the magnesium alloys DieMag422 and AE42 at room temperature (RT). The aim of this study was the comparison of both alloys regarding compression, tensile, and compression-compression fatigue behavior. The quasistatic behavior was determined by means of tensile and compression tests, and the tensile-compression asymmetry was analyzed. In temperature increase fatigue tests (TIFT) and constant amplitude tests (CAT), the temperature influence on the cyclic creeping (ratcheting) behavior was investigated, and mechanisms-relevant test temperatures were determined. Furthermore, characteristic fracture mechanisms were evaluated with investigations of the microstructure and the fracture surfaces. The initial material was analyzed in computed tomographic scans and energy dispersive X-ray (EDX) analyses.

scholarly journals Cyclic deformation behavior of an automotive material

2021 ◽  
Author(s):  
Amir Reza Emami
Keyword(s):  
Strain Hardening ◽  
Cyclic Deformation ◽  
Cast Alloy ◽  
A356 Alloy ◽  
Weight Ratio ◽  
High Strength ◽  
Cyclic Hardening ◽  
Fatigue Tests ◽  
Fracture Mechanisms ◽  
Strain Hardening Exponent

The A356 Al-Si-Mg cast alloy is being used in the automotive industry to replace some heavy components due to its fabrication flexibility and high strength-to-weight ratio. This study was aimed at identifying cyclic deformation characteristics and fracture mechanisms of the A356 alloy in different material conditions. The microstructure consisted of primary a-Al matrix and eutectic regions containing Si particles of acicular (T5) and spherical (T6 and ModT6) morphologies. The ModT6 sample had a higher yield strength (YS) and ultimate tensile strength (UTS) but a lower strain hardening exponent than the T6 sample, while the T5 sample had a lower YS UTS but a higher initial strain hardening than the T6 sample. The T6 sample exhibited a higher cyclic hardening capacity and longer fatigue life. Crack initiation in both tensile and fatigue tests occurred at the sub-surface voids. Quasi-cleavage fracture characteristics in the T5 condition and dimple-like fracture features in the T6 and ModT6 were observed.

Numerical Analysis of Self-Pierce Riveting of Magnesium Alloys

2013 ◽  
Author(s):  
J. F. C. Moraes ◽  
J. B. Jordon
Keyword(s):  
Magnesium Alloys ◽  
Elevated Temperatures ◽  
Internal State ◽  
Weight Ratio ◽  
High Strength ◽  
Material Model ◽  
The Finite Element Method ◽  
State Variable ◽  
Lightweight Metals ◽  
Joining Process

Regulations all over the world have been pushing vehicle manufacturers to increase fuel economies and decrease green house gas emissions. An effective way to meet these new regulations is to reduce automobile weight through the use of lightweight metals. Magnesium alloys have received recent interest due to its high strength-to-weight ratio. However, conventional fusion joining methods such as resistance spot welding are not effective for magnesium alloys. As such, an attractive joining technique for these lightweight metals is self-pierce riveting (SPR) which is fast, fumeless and does not melt the material. However, SPR must be performed at elevated temperatures because of the low ductility of magnesium alloys at room temperature. Even though the SPR joining process has been established on magnesium alloys, this joining process is not optimized. As such, this study establishes the first attempt at simulating the SPR of magnesium alloys through the use of the finite element method. An internal state variable (ISV) plasticity and damage material model was employed and comparison to experimental results show good results. The results of this study show that the ISV material model is ideally suited for modeling the SPR in magnesium alloys.

scholarly journals Cyclic deformation behavior of an automotive material

2021 ◽  
Author(s):  
Amir Reza Emami
Keyword(s):  
Strain Hardening ◽  
Cyclic Deformation ◽  
Cast Alloy ◽  
A356 Alloy ◽  
Weight Ratio ◽  
High Strength ◽  
Cyclic Hardening ◽  
Fatigue Tests ◽  
Fracture Mechanisms ◽  
Strain Hardening Exponent

The A356 Al-Si-Mg cast alloy is being used in the automotive industry to replace some heavy components due to its fabrication flexibility and high strength-to-weight ratio. This study was aimed at identifying cyclic deformation characteristics and fracture mechanisms of the A356 alloy in different material conditions. The microstructure consisted of primary a-Al matrix and eutectic regions containing Si particles of acicular (T5) and spherical (T6 and ModT6) morphologies. The ModT6 sample had a higher yield strength (YS) and ultimate tensile strength (UTS) but a lower strain hardening exponent than the T6 sample, while the T5 sample had a lower YS UTS but a higher initial strain hardening than the T6 sample. The T6 sample exhibited a higher cyclic hardening capacity and longer fatigue life. Crack initiation in both tensile and fatigue tests occurred at the sub-surface voids. Quasi-cleavage fracture characteristics in the T5 condition and dimple-like fracture features in the T6 and ModT6 were observed.

scholarly journals Fatigue Life Improvement of Cracked Aluminum 6061-T6 Plates Repaired by Composite Patches

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1421
Author(s):  
Armin Yousefi ◽  
Saman Jolaiy ◽  
Reza Hedayati ◽  
Ahmad Serjouei ◽  
Mahdi Bodaghi
Keyword(s):  
Fatigue Life ◽  
Fatigue Behavior ◽  
Weight Ratio ◽  
High Strength ◽  
Plastic Strain Amplitude ◽  
Composite Patch ◽  
Life Improvement ◽  
Cracked Structures ◽  
Aluminum Plates ◽  
High Flexibility

Bonded patches are widely used in several industry sectors for repairing damaged plates, cracks in metallic structures, and reinforcement of damaged structures. Composite patches have optimal properties such as high strength-to-weight ratio, easiness in being applied, and high flexibility. Due to recent rapid growth in the aerospace industry, analyses of adhesively bonded patches applicable to repairing cracked structures have become of great significance. In the present study, the fatigue behavior of the aluminum alloy, repaired by a double-sided glass/epoxy composite patch, is studied numerically. More specifically, the effect of applying a double-sided composite patch on the fatigue life improvement of a damaged aluminum 6061-T6 is analyzed. 3D finite element numerical modeling is performed to analyze the fatigue performance of both repaired and unrepaired aluminum plates using the Abaqus package. To determine the fatigue life of the aluminum 6061-T6 plate, first, the hysteresis loop is determined, and afterward, the plastic strain amplitude is calculated. Finally, by using the Coffin-Manson equation, fatigue life is predicted and validated against the available experimental data from the literature. Results reveal that composite patches increase the fatigue life of cracked structures significantly, ranging from 55% to 100% for different applied stresses.

scholarly journals Influence of Shot Peening on the Isothermal Fatigue Behavior of the Gamma Titanium Aluminide Ti-48Al-2Cr-2Nb at 750 °C

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1083
Author(s):  
Christoph Breuner ◽  
Stefan Guth ◽  
Elias Gall ◽  
Radosław Swadźba ◽  
Jens Gibmeier ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Shot Peening ◽  
Elevated Temperatures ◽  
Stress Amplitude ◽  
Negative Impact ◽  
Fatigue Behavior ◽  
Surface Hardness ◽  
Fatigue Tests ◽  
Positive Effects ◽  
Isothermal Fatigue

One possibility to improve the fatigue life and strength of metallic materials is shot peening. However, at elevated temperatures, the induced residual stresses may relax. To investigate the influence of shot peening on high-temperature fatigue behavior, isothermal fatigue tests were conducted on shot-peened and untreated samples of gamma TiAl 48-2-2 at 750 °C in air. The shot-peened material was characterized using EBSD, microhardness, and residual stress analyses. Shot peening leads to a significant increase in surface hardness and high compressive residual stresses near the surface. Both effects may have a positive influence on lifetime. However, it also leads to surface notches and tensile residual stresses in the bulk material with a negative impact on cyclic lifetime. During fully reversed uniaxial tension-compression fatigue tests (R = −1) at a stress amplitude of 260 MPa, the positive effects dominate, and the fatigue lifetime increases. At a lower stress amplitude of 230 MPa, the negative effect of internal tensile residual stresses dominates, and the lifetime decreases. Shot peening leads to a transition from surface to volume crack initiation if the surface is not damaged by the shots.

scholarly journals Changing in Fatigue Life of 300 M Bainitic Steel After Laser Carburizing and Plasma Nitriding

2018 ◽  
Vol 165 ◽  
pp. 21002 ◽  
Author(s):  
Antonio J. Abdalla ◽  
Douglas Santos ◽  
Getúlio Vasconcelos ◽  
Vladimir H. Baggio-Scheid ◽  
Deivid F. Silva
Keyword(s):  
Mechanical Properties ◽  
Fatigue Life ◽  
Plasma Nitriding ◽  
Fatigue Behavior ◽  
High Strength ◽  
Tensile Tests ◽  
Steel Sample ◽  
Fatigue Tests ◽  
300M Steel ◽  
Structural Applications

In this work 300M steel samples is used. This high-strength steel is used in aeronautic and aerospace industry and other structural applications. Initially the 300 M steel sample was submitted to a heat treatment to obtain a bainític structure. It was heated at 850 °C for 30 minutes and after that, cooled at 300 °C for 60 minutes. Afterwards two types of surface treatments have been employed: (a) using low-power laser CO2 (125 W) for introducing carbon into the surface and (b) plasma nitriding at a temperature of 500° C for 3 hours. After surface treatment, the metallographic preparation was carried out and the observations with optical and electronic microscopy have been made. The analysis of the coating showed an increase in the hardness of layer formed on the surface, mainly, among the nitriding layers. The mechanical properties were analyzed using tensile and fatigue tests. The results showed that the mechanical properties in tensile tests were strongly affected by the bainitic microstructure. The steel that received the nitriding surface by plasma treatment showed better fatigue behavior. The results are very promising because the layer formed on steel surface, in addition to improving the fatigue life, still improves protection against corrosion and wear.

High Cycle Fatigue Behavior of Recycled Additive Manufactured Electron Beam Melted Titanium Ti6Al4V

2020 ◽  
Author(s):  
Melody Mojib ◽  
Rishi Pahuja ◽  
M. Ramulu ◽  
Dwayne Arola
Keyword(s):  
Electron Beam ◽  
Fatigue Life ◽  
Rough Surface ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
High Strength ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Initiation And Propagation ◽  
Powder Recycling

Abstract Metal Additive Manufacturing (AM) has become a popular method for producing complex and unique geometries, especially gaining traction in the aerospace and medical industries. With the increase in adoption of AM and the high cost of powder, it is critical to understand the effects of powder recycling on part performance to move towards material qualification and certification of affordable printed components. Due to the limitations of the Electron Beam Melting (EBM) process, current as-printed components are susceptible to failure at limits far below wrought metals and further understanding of the material properties and fatigue life is required. In this study, a high strength Titanium alloy, Ti-6Al-4V, is recycled over time and used to print fatigue specimens using the EBM process. Uniaxial High Cycle Fatigue tests have been performed on as-printed and polished cylindrical specimens and the locations of crack initiation and propagation have been determined through the use of a scanning electron microscope. This investigation has shown that the rough surface exterior is far more detrimental to performance life than the powder degradation occurring due to powder reuse. In addition, the effects of the rough surface exterior as a stress concentration is evaluated using the Arola-Ramulu. The following is a preliminary study of the effects powder recycling and surface treatments on EBM Ti-6Al4V fatigue life.

The Processing and Fatigue Characterization of TiNi and Ti-6Al-4V Porous Materials

2011 ◽  
Vol 493-494 ◽  
pp. 930-935 ◽  
Author(s):  
Emin Erkan Aşik ◽  
Gül Ipek Nakaş ◽  
Şakir Bor
Keyword(s):  
Titanium Alloys ◽  
Endurance Limit ◽  
Fatigue Behavior ◽  
Porous Titanium ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Compression Tests ◽  
Limit Values ◽  
Porous Ti ◽  
Structural Applications

Porous titanium alloys have been extensively studied in biomedical applications due to their elastic moduli similar to that of bone compared to other implant materials. Accordingly, TiNi and Ti-6Al-4V foams have been widely characterized in terms of their various mechanical properties; however, their fatigue properties have not been well studied, even though, it has a vital importance in structural applications such as medical implants. In this study, porous titanium alloys were processed via sintering at 1200 °C for 2 hours employing Mg space holder technique. TiNi and Ti-6Al-4V alloys with a porosity of 49 and 51 vol.%, respectively, were mechanically characterized by monotonic and cyclic compression tests. The compressive strength was determined to be 148 MPa for TiNi foams whereas 172 MPa for Ti-6Al-4V foams with homogenously distributed pores having diameters in the range of 250-600 µm. Endurance limit values were determined relative to the yield strength of each porous alloy in order to enable the comparison of fatigue behavior. The fatigue tests applied with a frequency of 5 Hz and a constant stress ratio (σmin/σmax) of 0.1 have revealed that porous TiNi alloys have an endurance limit of approximately 0.6 σy whereas porous Ti-6Al-4V alloys have an endurance limit of approximately 0.75 σy. The differences and similarities in the microstructure and their effect on mechanical behavior of the two alloys were also studied by employing scanning electron microscope (SEM).

X-ray Fractographic Study on Alumina and Zirconia Ceramics

1990 ◽  
Vol 34 ◽  
pp. 719-727 ◽  
Author(s):  
Sumio Tanaka ◽  
Yukio Hirose ◽  
Keisuke Tanaka
Keyword(s):  
Fracture Toughness ◽  
Residual Stress ◽  
Fracture Surface ◽  
High Strength Steels ◽  
High Strength ◽  
Fatigue Tests ◽  
Fracture Mechanisms ◽  
Zirconia Ceramics ◽  
X Ray ◽  
Fractographic Study

The residual stress left on the fracture surface is one of the important parameters in X-ray fractographic study. It has been used to analyze fracture mechanisms in fracture toughness and fatigue tests especially of high strength steels.In this paper, X-ray fractography was applied to brittle fracture of alumina (Al2O3) and zirconia (ZΓO2) ceramics.

scholarly journals Damage Characterization of Nano-Interleaved CFRP under Static and Fatigue Loading

Fibers ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 13 ◽  
Author(s):  
Mohamad Fotouhi ◽  
Cristiano Fragassa ◽  
Sakineh Fotouhi ◽  
Hamed Saghafi ◽  
Giangiacomo Minak
Keyword(s):  
Acoustic Emissions ◽  
Weight Ratio ◽  
Laminated Composite ◽  
High Strength ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Limiting Factor ◽  
Delamination Toughness ◽  
Delamination Resistance ◽  
Laminated Composite Materials

The use of high strength-to-weight ratio-laminated fiber-reinforced composites is emerging in engineering sectors such as aerospace, marine and automotive to improve productivity. Nevertheless, delamination between the layers is a limiting factor for the wider application of laminated composites, as it reduces the stiffness and strengths of the structure. Previous studies have proven that ply interface nanofibrous fiber reinforcement has an effective influence on delamination resistance of laminated composite materials. This paper aims to investigate the effect of nanofiber ply interface reinforcement on mode I properties and failure responses when being subjected to static and fatigue loadings. For this purpose, virgin and nanomodified woven laminates were subjected to Double Cantilever Beam (DCB) experiments. Static and fatigue tests were performed in accordance with standards and the Acoustic Emissions (AE) were acquired during these tests. The results showed not only a 130% increase of delamination toughness for nanomodified specimens in the case of static loads, but also a relevant crack growth resistance in the case of fatigue loads. In addition, the AE permitted to relate these improvements to the different failure mechanisms occurring.

Sign in / Sign up

Export Citation Format

Share Document