A Study on Fatigue Properties of Sc Added Al 2519 Alloy

2005 ◽  
Vol 297-300 ◽  
pp. 2483-2488 ◽  
Author(s):  
Un Bong Baek ◽  
Jong Seo Park ◽  
In Hyun Chung ◽  
Seung Hoon Nahm ◽  
Young Hwa Ma ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Crack Nucleation ◽  
Coarse Grained ◽  
Tensile Yield Strength ◽  
Fatigue Properties ◽  
Subgrain Structure ◽  
Lower Yield ◽  
Lower Yield Stress ◽  
Fatigue Crack Nucleation ◽  
Fine Grained

The high cycle fatigue properties of two kinds of wrought Al 2519 alloys without and with scandium of 0.10% were investigated. The fatigue strength was determined at R = 0.1 under constant amplitude loading conditions in air. The alloy with scandium of 0.10% showed a little lower tensile yield strength and higher fatigue strength values. The fine grained Al-0.10Sc alloy exhibited a higher resistance against fatigue crack nucleation despite the lower yield stress in comparison to the coarse grained Al 2519 alloy. The results can be explained mainly with the microstructural differences between both alloys. This results are due to the presence of coherent Al3 (Sc, Zr) precipitates and a very fine subgrain structure.

A Study on Fatigue Properties of Sc and Zr Added Al Alloy

2007 ◽  
Vol 345-346 ◽  
pp. 657-660
Author(s):  
Un Bong Baek ◽  
Jong Seo Park ◽  
In Hyun Chung ◽  
Tae Won Park ◽  
Seung Hoon Nahm
Keyword(s):  
Fatigue Strength ◽  
Crack Nucleation ◽  
Grain Structure ◽  
Coarse Grained ◽  
Tensile Yield Strength ◽  
Fatigue Properties ◽  
Al Alloy ◽  
Fatigue Crack Nucleation ◽  
Al 6061 ◽  
Specific Strength

Al alloy is used extensively in several fields because specific strength is good and workability is superior. It is known that If Sc is added to Al alloy, strength is increased and re-crystallization temperature rises because microstructure becomes fine. The high cycle fatigue properties of four kinds of Al-Mg-Si alloys without and with only scandium of 0.20 % or with both scandium(Sc) of 0.20 % and zirconium(Zr) of 0.12% were investigated. The fatigue strength was determined at R = -1.0 under constant amplitude loading conditions in air. The alloy with scandium of 0.20 % showed a little higher fatigue strength values. The alloy with 0.20 % Sc and 0.12 % Zr showed highest tensile yield strength and highest fatigue strength. The fine grained Al 6061+0.20Sc+0.12Zr alloy exhibited a higher resistance against fatigue crack nucleation in comparison to the coarse grained Al 6061 alloy. The results can be explained mainly with the micro-structural differences among four alloys. This results are due to the presence of coherent Al3 (Sc, Zr) precipitates and a very fine sub-grain structure.

Crystal Plasticity Modeling of Laser Peening Effects on Tensile and High Cycle Fatigue Properties of 2024-T351 Aluminum Alloy

2021 ◽  
Vol 143 (7) ◽  
Author(s):  
Maziar Toursangsaraki ◽  
Huamiao Wang ◽  
Yongxiang Hu ◽  
Dhandapanik Karthik
Keyword(s):  
Residual Stresses ◽  
Crystal Plasticity ◽  
High Cycle Fatigue ◽  
Driving Forces ◽  
Crack Nucleation ◽  
Fatigue Properties ◽  
Laser Peening ◽  
Cycle Fatigue ◽  
Fatigue Crack Nucleation ◽  
Near Surface

Abstract This study aims to model the effects of multiple laser peening (LP) on the mechanical properties of AA2024-T351 by including the material microstructure and residual stresses using the crystal plasticity finite element method (CPFEM). In this approach, the LP-induced compressive residual stress distribution is modeled through the insertion of the Eigenstrains as a function of depth, which is calibrated by the X-ray measured residual stresses. The simulated enhancement in the tensile properties after LP, caused by the formation of a near-surface work-hardened layer, fits the experimentally obtained tensile curves. The model calculated fatigue indicator parameters (FIPs) under the following cyclic loading application show a decrease in the near-surface driving forces for the crystal slip deformation after the insertion of the Eigenstrains. This leads to a higher high cycle fatigue (HCF) resistance and the possible transformation of sensitive locations for fatigue failure further to the depth after LP. Experimental observations on the enhancement in the HCF life, along with the relocation of fatigue crack nucleation sites further to the depth, reveal the improvement in the HCF properties due to the LP process and validate the numerical approach.

Effect of Fine-Grained Microstructure Induced by Induction-Heating Fine Particle Peening Treatment on Fatigue Properties of Structural Steel (0.45%C)

2014 ◽  
Vol 891-892 ◽  
pp. 1482-1487
Author(s):  
Kazue Murai ◽  
Ryota Toyama ◽  
Jun Komotori ◽  
Kengo Fukazawa ◽  
Yoshitaka Misaka ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Structural Steel ◽  
Grain Refinement ◽  
Induction Heating ◽  
Fine Particle ◽  
Optical Microscope ◽  
Treatment Temperature ◽  
Fatigue Properties ◽  
Fine Grained

To improve the fatigue properties of structural steel, a novel surface modification process which combines high-frequency induction heating (IH) with fine particle peening (FPP) was developed. IH-FPP treatment was performed on the surface of structural steel specimens (0.45%C) at temperatures from 600 to 750 °C, with peening times of 60 and 120 s. To determine the characteristics of the treated surfaces, the microstructure was observed using an optical microscope and a scanning electron microscope. Vickers hardness and residual stress distributions were also measured. The characteristics of fine-grained microstructures were examined by electron backscatter diffraction. Furthermore, in order to investigate the effect of the grain refinement achieved by IH-FPP treatment, rotational bending fatigue tests were performed on treated specimens. Results showed that IH-FPP treatment created fine-grained microstructures beneath the surfaces of steel samples. The average ferrite grain size was 4.06 μm for a treatment temperature of 700 °C, and finally 0.76 μm for 600 °C . This was due to dynamic recrystallization in the processed region. IH-FPP treated specimens exhibited a higher fatigue strength than untreated specimens. As almost no compressive residual stress was measured in the treated or untreated specimens, the increase in fatigue strength resulting from IH-FPP treatment was due solely to grain refinement.

Low Cycle Fatigue and Fracture Behavior of Nickel-Base Superalloy CM247LC at 760°C

2004 ◽  
Vol 449-452 ◽  
pp. 561-564 ◽  
Author(s):  
Seong Moon Seo ◽  
In Sup Kim ◽  
Chang Yong Jo
Keyword(s):  
Fatigue Crack ◽  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Strain Range ◽  
Initiation Site ◽  
Coarse Grained ◽  
Fatigue Properties ◽  
Nickel Base Superalloy ◽  
Cycle Fatigue ◽  
Fine Grained

Low cycle fatigue (LCF) behavior of coarse and fine grained superalloy CM247LC at 760°C has been investigated. Both coarse and fine grained CM247LC showed similar cyclic stress response, however, the fine grained CM247LC specimen exhibited relatively uniform and superior fatigue properties to the coarse grained one. It was found that fatigue crack initiation of the alloy was keen to the applied strain range. Fatigue crack initiated at the surface of the specimen with high strain range (∆εt≥( 0.7%) while the initiation site moved to the internal defects at low strain range (∆εt≤0.6%).

On the Propagation of Lu¨ders Bands in Steel Strips

2000 ◽  
Vol 67 (4) ◽  
pp. 645-654 ◽  
Author(s):  
S. Kyriakides ◽  
J. E. Miller
Keyword(s):  
Yield Stress ◽  
Strain Level ◽  
Finite Element Models ◽  
Localized Deformation ◽  
Lower Yield ◽  
Lower Yield Stress ◽  
Fine Grained ◽  
Steel Strips ◽  
Initiation And Propagation ◽  
Transient Events

The initiation and propagation of Lu¨ders-type localized deformation in thin, fine grained steel strips in tension is studied through combined experimental and analytical efforts. Purely elastic deformation is terminated (upper yield stress) by localized deformation which tends to initiate along preferred directions. The strain level associated with this material instability is limited to two to five percent. When this strain level is achieved locally, the instability propagates via inclined fronts which separate coexisting regions of essentially elastic and plastically deformed materials. Under displacement controlled stretching, one or two fronts propagate in a steady-state manner (lower yield stress). The propagation of one and two fronts are simulated numerically using finite element models in which the material is modeled as a finitely deforming elastoplastic solid with an up-down-up nominal stress-strain response. The simulations capture the major events observed in the experiments such as the initiation process, the propagation of inclined fronts, kinking of the strip and the build up of moments, and the periodic straightening and moment reduction through transient events. This confirms that structural effects play a major role in the evolution of observed events. [S0021-8936(00)01604-4]

Transition in the Fretting Phenomenon Based on the Variabile Coefficient of Friction

2012 ◽  
Vol 463-464 ◽  
pp. 343-346
Author(s):  
Stefan Ghimişi ◽  
Liliana Luca ◽  
Gheorghe Popescu
Keyword(s):  
Small Amplitude ◽  
Crack Nucleation ◽  
Tangential Force ◽  
Fretting Wear ◽  
Partial Slip ◽  
Fatigue Properties ◽  
Fatigue Crack Nucleation ◽  
Slip Regime ◽  
Mixed Regime ◽  
Slip Transition

Fretting is now fully identified as a small amplitude oscillatory motion which induces a harmonic tangential force between two surfaces in contact. It is related to three main loadings, i.e. fretting-wear, fretting-fatigue and fretting corrosion. Fretting regimes were first mapped by Vingsbo. In a similar way, three fretting regimes will be considered: stick regime, slip regime and mixed regime. The mixed regime was made up of initial gross slip followed by partial slip condition after a few hundred cycles. Obviously the partial slip transition develops the highest stress levels which can induce fatigue crack nucleation depending on the fatigue properties of the two contacting first bodies. Therefore prediction of the frontier between partial slip and gross slip is required.

Characteristics of Repair Welds on Aged 2.25Cr-1Mo Steel for Creep and Creep-Fatigue Applications

2004 ◽  
Author(s):  
Yoshio Takagi ◽  
Shigeru Otsuki ◽  
Takuya Ito ◽  
Isamu Nonaka
Keyword(s):  
Weld Metal ◽  
Base Metal ◽  
Weak Link ◽  
Fem Analysis ◽  
Fatigue Tests ◽  
Coarse Grained ◽  
Fatigue Properties ◽  
Strain Concentration ◽  
Fine Grained ◽  
Creep Fatigue

The creep and the creep-fatigue properties of full repair welds (FRW) and partial repair welds (PRW) were evaluated in this study. Since the PRW contained the service-aged girth weld which was the weak link of the cross weld, the PRW was a shorter creep strength than the FRW. Moreover, the PRW showed a remarkably shorter creep-fatigue life compared to that of the FRW. In order to consider the poor creep-fatigue properties of PRW, finite element (FEM) analysis was conducted with experimentally measured material constants using service-aged base metal, aged weld metal, simulated coarse-grained HAZ, simulated fine-grained HAZ and repair weld metal. The analysis revealed that the strain concentrated on the aged and softened base metal or girth weld metal of the repair-welded cross weld specimen and not on the virgin cross weld specimen. The failure locations in creep-fatigue tests were close to the strain concentrated zone. Thus, the strain concentration is considered to work as a significant role and dominate the creep-fatigue properties of repair welds. In addition, the ductility of the weld metal was much less than that of the base metal. Consequently, the interaction of the strain concentration and the lack of ductility induced the lesser creep-fatigue properties of the PRW.

scholarly journals A critical review of the influence of hydrogen on the mechanical properties of medium-strength steels

2013 ◽  
Vol 31 (3-6) ◽  
pp. 85-103 ◽  
Author(s):  
Qian Liu ◽  
Andrej Atrens
Keyword(s):  
Tensile Stress ◽  
Yield Stress ◽  
Stress Ratio ◽  
Ultimate Tensile Stress ◽  
Fatigue Properties ◽  
Lower Yield ◽  
Good Resistance ◽  
Microstructural Characteristics ◽  
Lower Yield Stress ◽  
Medium Strength

AbstractAs medium-strength steels are promising candidates for the hydrogen economy, it is important to understand their interaction with hydrogen. However, there are only a limited number of investigations on the behavior of medium-strength steels in hydrogen. The existing literature indicates that the influences of hydrogen on the tensile properties of medium-strength steels are mainly the following: (i) the steel can be hardened by hydrogen, as demonstrated by an increase in the yield stress or ultimate tensile stress; (ii) some steels can be embrittled by hydrogen, as revealed by lower yield stress or ultimate tensile stress; (iii) in most cases, these steels may experience hydrogen embrittlement (HE), as indicated by a reduction in ductility. The degree of HE mainly depends on the test conditions and the steel. The embrittlement can lead to catastrophic brittle fracture in service. The influence of hydrogen on the fatigue properties of medium-strength steels is dependent on many factors such as the stress ratio, temperature, yield stress of the steel, and test frequency. Generally, the hydrogen influence on fatigue limit is small, whereas hydrogen can accelerate the fatigue crack growth rate, leading to a shorter fatigue life. Inclusions are an important factor influencing the properties of medium-strength steels in the presence of hydrogen. However, it is not possible to predict the influence of hydrogen for any particular steel that has not been experimentally evaluated or to predict service performance. It is not known why similar steels can have different behavior, ranging from good resistance to significant embrittlement. A better understanding of the microstructural characteristics is needed.

scholarly journals Fatigue strength of austempered ductile iron-to-steel dissimilar arc-welded joints

2021 ◽  
Author(s):  
G. Meneghetti ◽  
A. Campagnolo ◽  
D. Berto ◽  
E. Pullin ◽  
S. Masaggia
Keyword(s):  
Fatigue Strength ◽  
Ductile Iron ◽  
Welded Joints ◽  
Crack Nucleation ◽  
Fatigue Tests ◽  
International Standards ◽  
Austempered Ductile Iron ◽  
Metallographic Analysis ◽  
Fatigue Crack Nucleation ◽  
Selection Of

AbstractNowadays, the use of different classes of materials in the same structure is increased to keep pace with innovation and high structural performances. In this context, structural components made of different materials need to be joined together and a possible solution is given by arc welding. Dissimilar welded joints must often be able to withstand fatigue loads; however, Design Standards provide fatigue strength categories only for homogeneous welded joints. The aim of the present paper is to compare the fatigue behaviour of EN-GJS-1050 austempered ductile iron-to-S355J2 steel dissimilar joints to the categories of the corresponding homogeneous steel welded joints, as suggested in International Standards and Recommendations. For this purpose, experimental fatigue tests were performed on a selection of dissimilar welded details. First, the microstructure was identified by metallographic analysis; micro-hardness measurements were collected and residual stress profiles were obtained by using the X-ray diffraction technique on a selection of joints. Misalignments were quantified for all specimens. Then, experimental fatigue tests have been performed on a number of joint geometries subject to axial or bending fatigue loadings and tested in the as-welded conditions. The fracture surfaces of the joints have been analysed to locate fatigue crack nucleation sites.

Sign in / Sign up

Export Citation Format

Share Document