scholarly journals Cyclic Deformation Behavior of A Heat-Treated Die-Cast Al-Mg-Si-Based Aluminum Alloy

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4115
Author(s):  
Sohail Mohammed ◽  
Shubham Gupta ◽  
Dejiang Li ◽  
Xiaoqin Zeng ◽  
Daolun Chen
Keyword(s):  
Heat Treatment ◽  
Strain Amplitude ◽  
Cyclic Deformation ◽  
Stress Amplitude ◽  
Cyclic Hardening ◽  
Life Cycles ◽  
Total Strain ◽  
Total Strain Amplitude ◽  
Heat Treated ◽  
Die Cast

The purpose of this investigation was to study the low-cycle fatigue (LCF) behavior of a newly developed high-pressure die-cast (HPDC) Al-5.5Mg-2.5Si-0.6Mn-0.2Fe (AlMgSiMnFe) alloy. The effect of heat-treatment in comparison with its as-cast counterpart was also identified. The layered (α-Al + Mg2Si) eutectic structure plus a small amount of Al8(Fe,Mn)2Si phase in the as-cast condition became an in-situ Mg2Si particulate-reinforced aluminum composite with spherical Mg2Si particles uniformly distributed in the α-Al matrix after heat treatment. Due to the spheroidization of intermetallic phases including both Mg2Si and Al8(Fe,Mn)2Si, the ductility and hardening capacity increased while the yield stress (YS) and ultimate tensile strength (UTS) decreased. Portevin–Le Chatelier effect (or serrated flow) was observed in both tensile stress–strain curves and initial hysteresis loops during cyclic deformation because of dynamic strain aging caused by strong dislocation–precipitate interactions. The alloy exhibited cyclic hardening in both as-cast and heat-treated conditions when the applied total strain amplitude was above 0.4%, below which cyclic stabilization was sustained. The heat-treated alloy displayed a larger plastic strain amplitude and a lower stress amplitude at a given total strain amplitude, demonstrating a superior fatigue resistance in the LCF regime. A simple equation based on the stress amplitude of the first and mid-life cycles ((Δσ/2)first, (Δσ/2)mid) was proposed to characterize the degree of cyclic hardening/softening (D): D=±(Δσ/2)mid − (Δσ/2)first(Δσ/2)first, where the positive sign “+” represents cyclic hardening and the negative sign “−“ reflects cyclic softening.

scholarly journals Analysis of the Effective and Internal Cyclic Stress Components in the Inconel Superalloy Fatigued at Elevated Temperature

2011 ◽  
Vol 278 ◽  
pp. 393-398 ◽  
Author(s):  
Miroslav Šmíd ◽  
Martin Petrenec ◽  
Jaroslav Polák ◽  
Karel Obrtlík ◽  
Alice Chlupová
Keyword(s):  
Strain Amplitude ◽  
Effective Stress ◽  
Stress Amplitude ◽  
Cyclic Hardening ◽  
Cyclic Stress ◽  
Step Test ◽  
Total Strain Amplitude ◽  
Strain Response ◽  
Stress Strain ◽  
Stress Components

Cyclic multiple step test in strain control have been performed on cylindrical specimens of cast polycrystalline Inconel 738LC and 792-5A superalloys at 800 °C in laboratory atmosphere. Hysteresis loops were analyzed according to the statistical theory of hysteresis loop. The effective and internal stress components were evaluated. The effective stress of γ´ precipitate has significant influence on the stress-strain response both materials. The stress amplitude in IN 792-5A is higher than in IN 738LC at approximately same total strain amplitude due to significantly higher effective stress of γ´ phase. Cyclic hardening/softening curves and cyclic stress-strain curves using short-cut procedure were obtained. Cyclic hardening/softening behavior depends both on temperature and strain amplitude. Low amplitude straining is characterized by the saturation of the stress amplitude. In high amplitude straining slight softening was found. The cyclic stress-strain curves for both materials can be fitted by power law. Cyclic stress-strain response in terms of internal and effective stress components is discussed in relation to microstructural parameters of the materials. The observation of surface relief revealed the presence of persistent slip markings.

Cyclic Deformation Behavior of Ni3Ge Single Crystals At Room Temperature

1984 ◽  
Vol 39 ◽  
Author(s):  
Han-Ryong Pak ◽  
Leih-Ming Hsiung ◽  
Masaharu Kato
Keyword(s):  
Plastic Strain ◽  
Single Crystals ◽  
Strain Amplitude ◽  
Cyclic Deformation ◽  
Room Temperature ◽  
Stress Amplitude ◽  
Plastic Strain Amplitude ◽  
Total Strain Amplitude ◽  
Screw Dislocations ◽  
Stress Asymmetry

ABSTRACTFully reversed strain-controlled, tension-compression tests were performed at room temperature to study cyclic-deformation properties of Ni3Ge single crystals. The cyclic deformation is performed with the stress axis parallel to the [1 1.94 2.69] direction at a strain rate of 1.0 × 10-4 s-1 and at a total-strain amplitude between 5.0 × 10-4 and 1.5 × 10-3. Cyclic strain-hardening occurs to saturation over the range of the employed strain amplitudes. The cyclic-stress amplitude is higher in compression than in tension at a plastic-strain amplitude larger than 1 × 10-5 where screw dislocations are operative. This stress asymmetry becomes more prominent (i.e., the mean stress-amplitude becomes larger in magnitude) as the plastic-strain amplitude becomes larger. At a plastic-strain amplitude less than 1 × 10-5 where edge dislocations are operative, the stress amplitude is symmetric. A similar stress asymmetry is also observed for monotonic flow stress. The cyclic hardening is explained by considering an interaction between the screw dislocations.

Low Cycle Fatigue Behavior of Spray Formed Superalloy Rings

2011 ◽  
Vol 399-401 ◽  
pp. 1937-1941 ◽  
Author(s):  
Wen Yong Xu ◽  
Guo Qing Zhang ◽  
Zhou Li
Keyword(s):  
Strain Amplitude ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Hysteresis Loops ◽  
Cyclic Strain ◽  
Cyclic Hardening ◽  
Cyclic Stress ◽  
Total Strain ◽  
Total Strain Amplitude ◽  
Cycle Fatigue

Low cycle fatigue behavior of spray formed superalloy GH738 at 650°C has been investigated under fully reversed total strain-controlled mode. When strain amplitude (Δεt/2) is between 0.32% and 0.4%, cyclic stress response is stable under fully reversed constant total strain amplitude. The stabilized hysteresis loops narrowing sharply to a straight line indicates that the alloy exhibits typical elastic strain. The crack initiates single site from the surface. When strain amplitude is between 0.6% and 1.0%, cyclic hardening is observed until fracture. The tendency for hardening is found to increase with strain amplitude. The hyperesis loops expand gradually, which indicates that plastic deformation happens during cyclic deformation process. The crack initiates multi-sites from the surface. The cyclic strain-stress relationship of spray formed GH738 at 650°C can be illustrated by Δσ/2 =2017(Δεp/2)0.1489.The total strain-life function can expressed by Δεt/2=0.0071(2Nf)-0.0781+0.0647(2Nf) )-0.4914.

scholarly journals Low Cycle Fatigue Characteristics of Oxygen-Free Copper for Electric Power Equipment

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4237
Author(s):  
Takuma Tanaka ◽  
Togo Sugioka ◽  
Tatsuya Kobayashi ◽  
Ikuo Shohji ◽  
Yuya Shimada ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Electric Power ◽  
Stress Amplitude ◽  
Low Cycle Fatigue ◽  
Ebsd Analysis ◽  
Fatigue Properties ◽  
Power Equipment ◽  
Cycle Fatigue ◽  
Fracture Surfaces ◽  
Heat Treated

The effect of heat treatment on tensile and low cycle fatigue properties of the oxygen-free copper for electric power equipment was investigated. The heat treatment at 850 °C for 20 min, which corresponds to the vacuum brazing process, caused the grain growth and relaxation of strain by recrystallization, and thus, the residual stress in the oxygen-free copper was reduced. The tensile strength and 0.2% proof stress were decreased, and elongation was increased by the heat treatment accompanying recrystallization. The plastic strain in the heat-treated specimen was increased compared with that in the untreated specimen under the same stress amplitude condition, and thus, the low cycle fatigue life of the oxygen-free copper was degraded by the heat treatment. Striation was observed in the crack initiation area of the fractured surface in the case of the stress amplitude less than 100 MPa regardless of the presence of the heat treatment. With an increase in the stress amplitude, the river pattern and the quasicleavage fracture were mainly observed in the fracture surfaces of the untreated specimens, and they were observed with striations in the fracture surfaces of the heat-treated ones. The result of the electron backscattered diffraction (EBSD) analysis showed that the grain reference orientation deviation (GROD) map was confirmed to be effective to investigate the fatigue damage degree in the grain by low cycle fatigue. In addition, the EBSD analysis revealed that the grains were deformed, and the GROD value reached approximately 28° in the fractured areas of heat-treated specimens after the low cycle fatigue test.

scholarly journals High-Strength Reinforcing Steel Bars: Low Cycle Fatigue Behavior Using RGB Methodology

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Jorge E. Egger ◽  
Fabian R. Rojas ◽  
Leonardo M. Massone
Keyword(s):  
Fatigue Life ◽  
Strain Amplitude ◽  
Low Cycle Fatigue ◽  
High Strength ◽  
Image Correlation ◽  
Total Strain ◽  
Total Strain Amplitude ◽  
Reinforcing Steel ◽  
Cycle Fatigue ◽  
Steel Bars

AbstractLow cycle fatigue life of high-strength reinforcing steel bars (ASTM A706 Grade 80), using photogrammetry by RGB methodology is evaluated. Fatigue tests are performed on specimens under constant axial displacement with total strain amplitudes ranging from 0.01 to 0.05. The experimental observations indicate that buckling of high-strength reinforcing bars results in a damaging degradation of their fatigue life performance as the slenderness ratio increases, including an early rebar failure as the total strain amplitude increases since it achieves the plastic range faster. In addition to this, the results show that the ratio of the ultimate tensile strength to yield strength satisfies the minimum of 1.25 specified in ASTM A706 for reinforcement. On the other hand, the RGB methodology indicates that the axial strains measured by photogrammetry provide more accurate data since the registered results by the traditional experimental setup do not detect second-order effects, such as slippage or lengthening of the specimens within the clamps. Moreover, the RGB filter is faster than digital image correlation (DIC) because the RGB methodology requires a fewer computational cost than DIC algorithms. The RGB methodology allows to reduce the total strain amplitude up to 45% compared to the results obtained by the traditional setup. Finally, models relating total strain amplitude with half-cycles to failure and total strain amplitude with total energy dissipated for multiple slenderness ratios (L/d of 5, 10, and 15) are obtained.

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.

Industrial Heat Treatment of R-HPDC A356 Automotive Brake Callipers

2012 ◽  
Vol 192-193 ◽  
pp. 533-538 ◽  
Author(s):  
Levy Chauke ◽  
Heinrich Möller ◽  
Ulyate Andries Curle ◽  
Gonasagren Govender
Keyword(s):  
Heat Treatment ◽  
Tensile Properties ◽  
Automotive Industry ◽  
Laboratory Scale ◽  
Heat Treated ◽  
Die Cast ◽  
Eutectic Si ◽  
Hardness Increase ◽  
Cast Condition ◽  
Automotive Brake

Heat treatment of rheo-high pressure die cast (R-HPDC) A356 brake callipers has produced good mechanical properties on the laboratory scale. An industrial heat treatment is required to evaluate the applicability and conformance of the R-HPDC A356 brake callipers to the automotive industry. This research studied A356 brake callipers heat treated on the industrial scale with particular emphasis on the resulting microstructure, hardness and tensile properties. The eutectic Si-particle spheroidisation after solution heat treatment was achieved and observed with optical microscopy. A hardness increase from 64 to 100 Vickers was achieved from the as-cast condition to the industrially heat treated T6 condition. The heat treatment caused no significant variation in hardness and tensile properties from brake callipers within the same batch or from different batches. The yield and ultimate strengths of the industrial heat treated brake callipers were lower compared to the laboratory scale heat treatment properties, while the ductility increased, mainly due to quenching effects. Even though the industrial heat treated A356 brake callipers resulted in yield and ultimate tensile strengths lower than those achieved on a laboratory scale, they still exceeded the minimum specifications for gravity die cast A356 brake callipers.

Concept of Fatigue for Determining Characteristics of Materials with Strengthening

2012 ◽  
Vol 726 ◽  
pp. 43-48 ◽  
Author(s):  
Ewa Marcisz ◽  
Adam Niesłony ◽  
Tadeusz Łagoda
Keyword(s):  
Strain Amplitude ◽  
Additional Term ◽  
Cyclic Strain ◽  
Plastic Strain Amplitude ◽  
Total Strain ◽  
Total Strain Amplitude ◽  
High Alloy ◽  
High Alloy Steel ◽  
Actual Material ◽  
Best Fit

The paper presents the concept of division of the total strain amplitudes. Simulations were performed for high-alloy steel X6NiCr3220 for proposing a new curve of cyclic strain based on the best fit to the experimental points and plotted the hysteresis loop. Proposed allocation of the total strain amplitude in three parts: the plastic strain amplitude, strain amplitude and the amplitude of the linearly elastic strain coupled. In order to preserve the forms of popular formula Ramberg-Osgoda and Manson-Coffin-Basquin modified them in such a way that added to their member responsible for the description of the coupled strain. Inclusion of additional term leading to closer representation of the actual material properties.

scholarly journals Influence of the Solution and Artificial Aging Treatments on the Microstructure and Mechanical Properties of Die-Cast Al–Si–Mg Alloys

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 71
Author(s):  
Ho-Jung Kang ◽  
Jin-Young Park ◽  
Yoon-Suk Choi ◽  
Dae-Hyun Cho
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Solid Solution ◽  
Artificial Aging ◽  
Solution Treatment ◽  
Mg Alloys ◽  
Needle Type ◽  
Heat Treated ◽  
Die Cast ◽  
Eutectic Si

Heat treatment is widely used to improve the properties of Al–Si–Mg alloys and its outcomes are influenced by the parameters applied during the treatment. This study describes the effect of the solution and artificial aging treatments on the microstructure and mechanical properties of die-cast Al–Si–Mg alloys. The microstructure of the as-cast Al–Si–Mg alloy was mainly composed of α-Al, complex needle-type eutectic Si particles, Mg2Si, and α-AlFeMn. The complex needle-type eutectic Si particles disintegrated into spheroidal morphologies, while the Mg2Si was dissolved due to the solid solution treatment. The maximum yield strength (YS) and ultimate tensile strength (UTS) values were 126.06 and 245.90 MPa at 520 °C after 90 min of solution heat treatment, respectively. Although the YS and UTS values of the Al–Si–Mg alloys reduced due to the solution treatment, the elongation (EL) of the solid solution heat-treated Al–Si–Mg alloys was improved in comparison to that of the as-cast Al–Si–Mg alloy. The maximum YS and UTS of 239.50 and 290.93 MPa were obtained after performing artificial aging at 180 °C for 180 min, respectively. However, the EL of the aging heat-treated alloy was reduced by a minimal value.

High Temperature Low Cycle Fatigue Characteristics of Grit Blasted Polycrystalline Ni-Base Superalloy

2015 ◽  
Vol 665 ◽  
pp. 73-76 ◽  
Author(s):  
Ivo Šulák ◽  
Karel Obrtlík ◽  
Ladislav Čelko
Keyword(s):  
Fatigue Life ◽  
Strain Amplitude ◽  
Low Cycle Fatigue ◽  
Total Strain ◽  
Material Surface ◽  
Total Strain Amplitude ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Fatigue Characteristics ◽  
Base Superalloy

The present work is focused on the study of low cycle fatigue behavior of grit blasted nickel-base superalloy Inconel 713LC (IN 713LC). Grit blasting parameters are obtained. Button end specimens of IN 713LC in as-received condition and with grit blasted surface were fatigued under strain control with constant total strain amplitude in symmetrical cycle at 900 °C in air. Hardening/softening curves, cyclic stress-strain curve and fatigue life data of both materials were obtained. Both materials exhibit the same stress-strain response. It has not been observed any improvement or reduction of low cycle fatigue life in representation of total strain amplitude versus number of cycles to failure of grit blasted material in comparison with as-received material. Surface relief and fracture surface were observed in SEM. The little effect of surface treatment on fatigue characteristics is discussed.

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