Decomposition of solid solution in an alloy under high plastic strain

The low-cycle fatigue (LCF) properties of a nickel-base precipitation-strengthened superalloy (GH4145/SQ), obtained at a temperature of 538 o C, were reported and discussed in this paper. The properties investigated include cyclic stress response, fatigue life, deformation microstructure and final fracture features as a function of applied strain amplitude. It was shown that the alloy exhibited a pronounced initial hardening followed by continuous softening to failure at high plastic strain amplitudes ( > 0.2% ap ε ), while at low plastic strain amplitudes ( < 0.2% ap ε ) the initial hardening was followed by a well-defined saturation stage. Bilinear behavior with a change of slope at a plastic strain amplitude of about 0.2% was observed in the cyclic stress-strain (CSS) and Coffin-Manson (C-M) plots. TEM observations revealed that slip band density increased with increasing total strain amplitude and precipitate degradation resulting from dislocation-precipitate interactions took place with continuous cyclic straining. The change in the microstructure during cycling is thus responsible for the fatigue hardening / softening behavior of the alloy. SEM examinations indicated that at low plastic strain amplitudes ( < 0.2% ap ε ) crack propagation was basically transgranular, while at high plastic strain amplitudes ( > 0.2% ap ε ) crack propagation exhibited intergranular features, as a whole. The variation in both the number of operating slip systems and the fracture modes with the strain amplitude employed was used to explain the observed two-stage LCF behavior of the present investigated superalloy.

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Grain refinement of LY2 aluminum alloy induced by ultra-high plastic strain during multiple laser shock processing impacts

Acta Materialia ◽

10.1016/j.actamat.2010.03.026 ◽

2010 ◽

Vol 58 (11) ◽

pp. 3984-3994 ◽

Cited By ~ 201

Author(s):

J.Z. Lu ◽

K.Y. Luo ◽

Y.K. Zhang ◽

C.Y. Cui ◽

G.F. Sun ◽

...

Keyword(s):

Aluminum Alloy ◽

Plastic Strain ◽

Grain Refinement ◽

Laser Shock ◽

Laser Shock Processing ◽

High Plastic Strain ◽

Shock Processing ◽

High Plastic

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The Microstructure and Properties of LY12 Aluminum Alloy by Ultra-High Plastic Strain

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.464.708 ◽

2011 ◽

Vol 464 ◽

pp. 708-711

Author(s):

Ling Feng Zhang ◽

Kai Yu Luo ◽

J.Z. Lu ◽

Y. Xiong ◽

Y.Z. Wang

Keyword(s):

Electron Microscopy ◽

Aluminum Alloy ◽

Plastic Strain ◽

Surface Hardness ◽

Laser Shock ◽

Laser Shock Processing ◽

Plastic Deformation Behavior ◽

High Plastic Strain ◽

Shock Processing ◽

High Plastic

The ultra-high plastic deformation behavior by laser shock processing on the LY12 aluminum alloy had been investigated. The morphology of the materials had been analyzed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It was found that the grain refinement layer was formed in the thickness of about 100μm .The dislocation density of LY12 aluminum alloy should be large increased after laser shocking because the accumulation of dislocation was appeared on the grain boundary. With the laser energy density increased there formed subgrain structure and eventually generate ultra-fine grain. Hardness test results also show that the surface hardness obtains a big growth about 60% after laser shock processing. The results showed that the formation of ultra-high plastic strain can improve the surface hardness of LY12 aluminum alloy, and thus effectively improve the comprehensive mechanical properties.

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Effective Design of Cr-Co-Ni-Ta Eutectic Medium Entropy Alloys with High Compressive Properties Using Combined CALPHAD and Experimental Approaches

Applied Sciences ◽

10.3390/app11136102 ◽

2021 ◽

Vol 11 (13) ◽

pp. 6102

Author(s):

Taiwen Huang ◽

Jiachen Zhang ◽

Jun Zhang ◽

Lin Liu

Keyword(s):

Solid Solution ◽

Plastic Strain ◽

Compression Strength ◽

Volume Fraction ◽

Laves Phase ◽

Valence Electron Concentration ◽

Solid Solution Strengthening ◽

Binary Diagram ◽

High Plastic Strain ◽

The Stability

Alloy design of Cr-Co-Ni-Ta eutectic medium entropy alloys (EMEAs) was performed through a CALPHAD method coupled with experimental study, with the aim to attain high phase stability as well as excellent mechanical properties. Based on calculated pseudo-binary diagram, CrCoNiTax (x = 0.1, 0.3, 0.4, 0.5, 0.7) medium entropy alloys were investigated. Two phases, FCC solid solution and Laves phase, were identified in the alloys. With increasing Ta content, the volume fraction of hard and brittle Laves phase increased, microstructure changed from hypoeutectic (Ta0.1, Ta0.3) to eutectic (Ta0.4) and then to hypereutectic (Ta0.5, Ta0.7). The stability of phases was assessed by considering the thermodynamic parameter Ω and valence electron concentration (VEC). The eutectic phases become stable when 1.42 < Ω < 0.74 and 7.5 < VEC < 8.25. In addition, based on nanoindentation, the results indicated that solid solution strengthening in γ phase was significantly enhanced, eutectic phase in CrCoNiTa0.4 EMEA was found to process the highest microhardness and elastic modulus. Finally, the hardness of alloys was positively correlated with the content of Ta and the plastic strain of alloys obviously decreased, while the compression strength firstly increased and then decreased. CrCoNiTa0.4 was the most promising alloy with the highest compression strength (2502 MPa) and high plastic strain (20.6%).

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Very High Plastic Strain Zones in 304 Stainless Steel Small Punch Specimen Loaded at RT by Martensite Formation and Recrystallization Technique

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.627.429 ◽

2014 ◽

Vol 627 ◽

pp. 429-432

Author(s):

Y. Iino ◽

Hyu Sun Yu ◽

J.H. Kong ◽

Masahiro Okumiya

Keyword(s):

Stainless Steel ◽

Plastic Strain ◽

Contact Region ◽

Equivalent Plastic Strain ◽

304 Stainless Steel ◽

Martensite Formation ◽

Small Punch ◽

High Plastic Strain ◽

High Plastic ◽

Very High

Very high plastic strain zones with equivalent plastic strain above 0.2, PZ0.2 and above 0.5, PZ0.5 in 304 stainless steel small punch specimens loaded at RT to various level were observed and measured by martensite formation and recrystallization technique, respectively. It is found that both the very high plastic zones are formed ,at middle stage of the small punch test, at first near the outer surface region of the specimen where the loading ball is contacted to the specimen. The zones extend with increasing load toward the inner surface. Thus the contact area part of the specimen with the ball causes a significant strain gradient through thickness. This will be due to the constraint of the plastic deformation near the contact region by the friction force.

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Analysis of Stress and Strain in the Equal Channel Angular Drawing Process

Materials Science Forum ◽

10.4028/www.scientific.net/msf.526.19 ◽

2006 ◽

Vol 526 ◽

pp. 19-24 ◽

Cited By ~ 2

Author(s):

Javier León ◽

C.J. Luis-Pérez

Keyword(s):

Plastic Strain ◽

Cross Section ◽

Three Dimensional ◽

Longitudinal Axis ◽

Wire Drawing ◽

Stress And Strain ◽

Drawing Process ◽

The Cross ◽

High Plastic Strain ◽

High Plastic

The equal channel angular drawing (ECAD) process is an innovative method to obtain materials with high plastic strain in a continuous way. This deformation is higher than the deformation achieved by a conventional wire drawing process, for the same reduction of the cross section, so if an adequate thermal treatment is employed later, it could be possible to obtain an initial material with high value that could be useful in conventional manufacturing processes. This process consists in drawing a material through a die where two circular channels intersect at an angle between 90º and 135º. In this work a study using finite element of the plastic strain and the stresses that appear for one aluminium alloy AA-1370 has been carried out. Two ECAD passes have been made, where for the second pass the billet has been rotated 180º along the longitudinal axis. Finally, a calibrated pass has been carried out in order to obtain the billet with homogeneous dimensions in all the cross section. All the simulations have been calculated at room temperature and by using good conditions of lubrication. In order to perform the FEM simulations, a three dimensional geometry has been used. To analyze by FEM the second ECAD pass and the calibration pass, the deformations and stresses achieved in the previous passes have been taken into consideration. This has been done with the aim of achieving higher accuracy. Moreover, a comparative analysis with experimental results has been carried out.

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Local Mesh Refinement for Correlation of FEA Estimated Plastic Strain to Tests in Areas of High Plastic Strain

Volume 3B: Design and Analysis ◽

10.1115/pvp2018-84630 ◽

2018 ◽

Author(s):

Katharine Liu ◽

Emma Xiao ◽

Gregory Westwater ◽

Christopher R. Johnson ◽

J. Adin Mann

Keyword(s):

Plastic Strain ◽

Mesh Refinement ◽

Sensitivity Study ◽

Linear Elastic ◽

Mesh Sensitivity ◽

Local Mesh Refinement ◽

Order Of Magnitude ◽

High Plastic Strain ◽

Stabilization Technique ◽

The Impact

The total strain, elastic plus plastic, was measured with strain gages on valve bodies with internal pressure that caused surface yielding. The correlation of the simulated maximum principal strain was compared to strain gage data. A mesh sensitivity study shows that in regions of large plastic strain, mesh elements are required that are an order of magnitude smaller than what is used for linear elastic stress analysis for the same structure. A local mesh refinement was adequate to resolve the local high strain values. Both the location and magnitude of the maximum strain changed with a local mesh refinement. The local mesh refinement requirement was consistent over several structures that were tested. The test and simulation work will be presented along with the mesh sensitivity study. Some results on using an energy stabilization technique to aid convergence will be presented in terms of the impact on the predicted plastic strain.

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