Impression Creep Behaviour of Extruded Mg-Sn Alloy

2016 ◽  
Vol 8 (3) ◽  
Author(s):  
V. Thenambika ◽  
S. Jayalakshmi ◽  
R.A. Singh ◽  
J.K. Nidhi ◽  
M. Gupta
Keyword(s):  
Activation Energy ◽  
Stress Exponent ◽  
Creep Deformation ◽  
Creep Behaviour ◽  
Impression Creep ◽  
Temperature Dependent ◽  
Creep Tests ◽  
Automobile Engine ◽  
Creep Curves ◽  
Mg2sn Phase

Mg-Sn alloys contain thermally stable Mg2Sn phase, and are proposed as heat-resistant alloys for automobile engine applications. In this study, the creep behaviour of Mg-5Sn alloy was investigated using impression creep technique. The impression creep tests were carried out under constant punching stress in the range of 80-320 MPa at temperatures 373-573 K, for dwell times up to 5 hours. The results highlight that creep of Mg-5Sn alloy was load and temperature dependent, i.e. increasing the load and temperature resulted in larger creep deformation and hence to higher creep rates. From the creep curves, the stress exponent and the activation energy were estimated and the creep mechanism was identified.

Impression Creep Characteristics of Mg-Sn-Ag Alloy

2016 ◽  
Vol 854 ◽  
pp. 33-37
Author(s):  
S. Jayalakshmi ◽  
R. Arvind Singh ◽  
V. Thenambika ◽  
J. Kirubanidhi ◽  
Manoj Gupta
Keyword(s):  
Thermal Stability ◽  
High Thermal Stability ◽  
Mg Alloys ◽  
Impression Creep ◽  
Alloying Element ◽  
Temperature Dependent ◽  
Creep Tests ◽  
Automobile Engine ◽  
Creep Characteristics ◽  
A Minor

Magnesium alloys with enhanced thermal stability are being developed for automobile engine applications. The available commercial Mg-alloys are usually alloyed with aluminum that are thermally stable only for T < 150o C. Development of new Mg-alloys is underway and Mg-Sn alloys are a promising option. In Mg-Sn alloy, the Mg2Sn phase has high thermal stability and is expected to enhance the high temperature properties. In this study, Mg-5Sn alloy is incorporated with Ag as a minor alloying element (0.175 wt. %). The creep behavior of the Mg-Sn-Ag alloy is investigated using the impression creep technique. The impression creep tests were carried out under punching stress in the range of 80-320 MPa and temperature of 373-573 K, for dwell times up to 5 hours. The results highlight that creep of the alloy was load and temperature dependent, i.e. increasing the load and temperature resulted in higher creep rates.

Creep Behavior of Two Series Magnesium Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 1596-1601 ◽  
Author(s):  
Yang Shan Sun ◽  
Jing Bai ◽  
Feng Xue
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Stress Exponent ◽  
Magnesium Alloys ◽  
Creep Behavior ◽  
Creep Deformation ◽  
Grain Boundary Sliding ◽  
Creep Tests ◽  
Sharp Drop ◽  
Creep Properties

The creep behavior of two series of magnesium alloys, Mg-4Al based alloys with strontium addition and binary Mg-Nd alloys, has been studied. Results show that the high creep properties achieved by the Mg-Nd alloys are attributed to the precipitation of tiny dispersed β’ particles, which form and effectively restrict the dislocation slipping and climb during creep deformation. In terms of values of the stress exponent and apparent activation energy gained from systematic creep tests, the mechanism responsible for creep deformation of the Mg-Nd alloys is inferred as dislocation climb, which is supported by TEM observations performed on the Mg-2Nd alloy after creep test. For the Mg-4Al based alloys, however, microstructural observations reveal that the significant improvement on creep properties caused by Sr addition is accounted for the formation of an interphase network consisting of Al4Sr and a Mg-Al-Sr ternary compound distributing at grain boundaries. The breakage of the interphase network after extrusion results in a sharp drop of creep properties, indicating the creep deformation of the alloy is controlled mainly by grain boundary sliding, which is in contradiction to the mechanism for creep of the alloys inferred by the classical criterions based on the values of stress exponent and apparent activation energy.

scholarly journals High Temperature Creep Behaviour of Cast Nickel-Based Superalloys INC 713 LC, B1914 and MAR-M247

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 152
Author(s):  
Marie Kvapilova ◽  
Petr Kral ◽  
Jiri Dvorak ◽  
Vaclav Sklenicka
Keyword(s):  
High Temperature ◽  
Stress Exponent ◽  
Creep Deformation ◽  
Creep Behaviour ◽  
Constant Load ◽  
Strength Properties ◽  
Creep Tests ◽  
Creep Properties ◽  
High Temperature Components ◽  
High Level

Cast nickel-based superalloys INC713 LC, B1914 and MAR-M247 are widely used for high temperature components in the aerospace, automotive and power industries due to their good castability, high level of strength properties at high temperature and hot corrosion resistance. The present study is focused on the mutual comparison of the creep properties of the above-mentioned superalloys, their creep and fracture behaviour and the identification of creep deformation mechanism(s). Standard constant load uniaxial creep tests were carried out up to the rupture at applied stress ranging from 150 to 700 MPa and temperatures of 800–1000 °C. The experimentally determined values of the stress exponent of the minimum creep rate, n, were rationalized by considering the existence of the threshold stress, σ0. The corrected values of the stress exponent correspond to the power-law creep regime and suggest dislocation climb and glide as dominating creep deformation mechanisms. Fractographic observations clearly indicate that the creep fracture is a brittle mostly mixed transgranular and intergranular mode, resulting in relatively low values of fracture strain. Determined main creep parameters show that the superalloy MAR-M247 exhibits the best creep properties, followed by B1914 and then the superalloy INC713 LC. However, that each of the investigated superalloys can be successfully used for high temperature components fulfils the required service loading conditions.

Microstructures and Creep of AM50-Sb-Gd Alloys

2005 ◽  
Vol 488-489 ◽  
pp. 749-752 ◽  
Author(s):  
Su Gui Tian ◽  
Keun Yong Sohn ◽  
Hyun Gap Cho ◽  
Kyung Hyun Kim
Keyword(s):  
Activation Energy ◽  
Creep Rate ◽  
Stress Exponent ◽  
Creep Behavior ◽  
Creep Deformation ◽  
Deformation Mechanism ◽  
Creep Resistance ◽  
Fine Particles ◽  
Dislocation Climb ◽  
The Matrix

Creep behavior of AM50-0.4% Sb-0.9%Gd alloy has been studied at temperatures ranging from 150 to 200°C and at stresses ranging from 40 to 90 MPa. Results show that the creep rate of AM50-0.4%Sb-0.9%Gd alloy was mainly controlled by dislocation climb at low stresses under 50 MPa. The activation energy for the creep was 131.2 ± 10 kJ/mol and the stress exponent was in the range from 4 to 9 depending on the applied stress. More than one deformation-mechanism were involved during the creep of this alloy. Microstructures of the alloy consist of a–Mg matrix and fine particles, distinguished as Mg17Al12, Sb2Mg3, and Mg2Gd or Al7GdMn5 that were homogeneously distributed in the matrix of the alloy, which effectively reduced the movement of dislocations, enhancing the creep resistance. Many dislocations were identified to be present on non-basal planes after creep deformation.

scholarly journals The Creep Activation Energies of Ice

1978 ◽  
Vol 21 (85) ◽  
pp. 429-444 ◽  
Author(s):  
D. R. Homer ◽  
J. W. Glen
Keyword(s):  
Activation Energy ◽  
Grain Boundary ◽  
Creep Deformation ◽  
Tensile Axis ◽  
Strain Rates ◽  
Boundary Slip ◽  
Creep Tests ◽  
Creep Activation Energy ◽  
Single Grain ◽  
Image Position

AbstractMonocrystals and bicrystals of ice have been creep tested at temperatures between 4 and — 30°C. The bicrystals had a single grain boundary running parallel to the tensile axis; this configuration inhibited grain-boundary slip between the two grains. The creep tests, which were carried out at constant stress σ and temperature T, yielded data of strain ϵ for time elapsed since the start of the test. These data showed accelerating creep for both monocrystals and bicrystals at all strain levels. Strain-rates were derived at strains of 0.01, 0.05. and 0.10, and these rates were fitted to the expressionk is Boltzmann’s constant and E is the creep activation energy. Derived values of n were 1.9 for monocrystals and 2.9 for bicrystals. The creep activation energy was found to be 78 kJ/mol for monocrystals and 75 kJ/mol for bicrystals. The processes of creep deformation in mono-, bi- and polycrystals are discussed.

scholarly journals Fabrication of Friction Stir Processed Al-Ni Particulate Composite and Its Impression Creep Behaviour

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Prakrathi Sampath ◽  
Vineeth Krishna Parangodath ◽  
Kota Rajendra Udupa ◽  
Udaya Bhat Kuruveri
Keyword(s):  
Activation Energy ◽  
Creep Rate ◽  
Base Metal ◽  
Creep Behaviour ◽  
Particulate Composite ◽  
Base Plate ◽  
Xrd Analysis ◽  
Maximum Temperature ◽  
Impression Creep ◽  
Friction Stir

Nickel powders were troweled on roughened Al base plate using a friction tool made from tool steel. Friction stir processing (FSP) was carried out using a load of 8 kN and with a tool rotation speed of 800 rpm and thus a surface composite was processed. Processed samples were characterized for revealing the microstructural features. SEM and XRD analysis revealed the presence of fine Ni particles in the stir zone which lead to a significant increase in hardness. Using the “refined energy model,” the maximum temperature developed within the processed zone was estimated and found to be around 275°C. Impression creep behaviour was assessed on both the base metal and processed zone at the temperature of 30, 100, and 200°C. Creep curves were generated and steady state creep rate (SSCR) values were found out to determine the activation energy. It is observed that friction stirred regions record higher creep rate values compared to the base metal. Estimated activation energy is in the range of 6 to 16 kJ/mol. Activation energy is marginally lower in the base metal compared to friction stir processed region.

scholarly journals Microstructure and impression creep characteristics Al-9Si-xCu aluminum alloys

10.30544/101 ◽  
2015 ◽  
Vol 21 (2) ◽  
pp. 115-126 ◽  
Author(s):  
Mohsen Yousefi ◽  
Mehdi Dehnavi ◽  
S.M. Miresmaeili
Keyword(s):  
Activation Energy ◽  
Aluminum Alloys ◽  
Intermetallic Compound ◽  
Stress Exponent ◽  
Creep Behavior ◽  
Eutectic Phase ◽  
Dislocation Creep ◽  
Impression Creep ◽  
Pipe Diffusion ◽  
Creep Characteristics

The effects of 1.5, 2.5 and 3.5 wt.% Cu additions on the microstructure and creep behavior of the as-cast Al-9Si alloy were investigated by impression tests. The tests were performed at temperature ranging from 493 to 553 K and under punching stresses in the range 300 to 414 MPa for dwell times up to 3000 seconds. The results showed that, for all loads and temperatures, the Al–9Si–3.5Cu alloy had the lowest creep rates and thus, the highest creep resistance among all materials tested. This is attributed to the formation of hard intermetallic compound of Al2Cu, and higher amount of α-Al2Cu eutectic phase. The stress exponent and activation energy are in the ranges of 5.2- 7.2 and 115 -150 kJ/ mol, respectively for all alloys. According to the stress exponent and creep activation energies, the lattice and pipe diffusion- climb controlled dislocation creep were the dominant creep mechanism.

Graded Creep Deformation Properties of 316H Welds and its Impact on Creep

2018 ◽  
Author(s):  
S. Dey ◽  
D. M. Knowles ◽  
C. E. Truman
Keyword(s):  
Stress Distribution ◽  
Base Metal ◽  
Creep Deformation ◽  
Creep Damage ◽  
Impression Creep ◽  
Uniform Stress ◽  
Creep Tests ◽  
Creep Ductility ◽  
Uniaxial Creep ◽  
Deformation Properties

The creep damage evolution in multi-pass welds is believed to be influenced by the variation of creep rates from the weld to the base metal and through the HAZ. Material heterogeneity in a multi-pass weld leads to a non-uniform stress distribution resulting in non-uniform evolution of creep strains with strain localisation. Also, a non-uniform stress distribution may lead to highly multiaxial stress states in the weld resulting in a lower creep ductility. Since creep damage in metallic components is influenced by creep strain rate and creep ductility of the material amongst other factors, creep inhomogeneity in a weldment may significantly affect creep damage accumulation. Therefore, in order to predict creep behaviour of a multi-pass weld, it is important to take into account the gradation of creep deformation properties through the weld HAZ. Impression creep tests are useful in revealing localised creep properties in a material, where test results can be directly correlated to uniaxial creep tests. In this paper, a 2D finite element model of a multipass 316H weld with three different material sections (weld, HAZ, parent) is used to demonstrate the effects of creep deformation mismatch on stress and strain distributions. The paper also describes a series of impression creep tests planned and being conducted on an ex-service 316H weldment from a power plant steam generator with specimens taken from locations in the HAZ and at varying proximities to the weld fusion line. One specimen from the far away base metal and one from the weld centerline were also taken to serve as reference since the uniaxial creep deformation properties for the weld and the base material are known from uniaxial creep tests. By comparing the minimum creep rates for the HAZ specimens against the reference specimens from the weld and the base metal, Norton’s law creep coefficients and stress exponents will be derived for the HAZ specimens thereby revealing the gradation of creep deformation properties as a function of distance from the weld fusion line.

Creep of Si3N4 Based Ceramics for Thermo-Mechanical Applications

2008 ◽  
Vol 591-593 ◽  
pp. 667-672
Author(s):  
Claudinei dos Santos ◽  
Kurt Strecker ◽  
M.J.R. Barboza ◽  
Francisco Piorino Neto ◽  
Olivério Moreira Macedo Silva ◽  
...  
Keyword(s):  
Activation Energy ◽  
Rare Earth ◽  
Creep Behavior ◽  
Creep Deformation ◽  
Phase Content ◽  
Creep Tests ◽  
Intergranular Phase ◽  
Aspect Ratios ◽  
Compressive Stresses ◽  
N2 Atmosphere

Commercial α−Si3N4, Al2O3 and a mixed yttrium and rare earth oxides, RE2O3, were used as starting-powders. Powder batches were milled using different Al2O3/RE2O3 contents, as additive. Hot-pressing was done at 1750oC-30 min-20MPa in N2 atmosphere. Specimens neat to 6x3x3mm3 were polished and characterized by XRD and SEM. Specimens were submitted to creep tests, under compressive stresses between 100 and 350 MPa at temperatures ranging from 1250 to 1300oC in air. Higher additive amounts resulted in larger grains of higher aspect ratios and in a decreased anisotropy in the hot-pressed ceramics. The compressive creep behavior depends on the intergranular phase content. While higher amounts of additives resulted in higher creep rates, • ε , and higher stress exponents, n, the activation energy Qss, has been inferior for samples with lower additive contents. Grain sliding has been identified to be the predominant mechanism responsible for creep deformation of these ceramics.

scholarly journals Effect of Temperature on the Creep of Ice

1969 ◽  
Vol 8 (52) ◽  
pp. 131-145 ◽  
Author(s):  
Malcolm Mellor ◽  
Richard Testa
Keyword(s):  
Activation Energy ◽  
Creep Rate ◽  
Single Crystal ◽  
Apparent Activation Energy ◽  
Creep Curve ◽  
Effect Of Temperature ◽  
Temperature Dependent ◽  
Creep Tests ◽  
Polycrystalline Ice ◽  
Rate Relation

Creep tests on homogeneous, isotropic polycrystalline ice gave an apparent activation energy for creep of 16.4 kcal/mol (68.8 kJ/mol) over the temperature range −10° to −60° C. Above −10° C the Arrhenius relation for temperature dependence is invalid, and creep rate becomes progressively more temperature dependent as the melting point is approached. Between −20° and −50° C the apparent activation energy for creep of a single crystal of ice was found to be 16.5 kcal/mol (69.1 kJ/mol). A complete creep curve for a single crystal loaded in uniaxial compression parallel to the basal plane was qualitatively similar to the classical creep curve; creep rate at all stages was very much faster than for polycrystalline ice under the same conditions. Creep tests on polycrystalline ice at 0° C gave a stress/strain-rate relation for that temperature, but its precise meaning is unclear, since recrystallization complicated the results.

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