Effect of Cu and Mg on Forging Property and Mechanical Behavior of Powder Forged Al-Si-Fe Based Alloy

2007 ◽  
Vol 534-536 ◽  
pp. 389-392
Author(s):  
Dong Suk Lee ◽  
Taek Kyun Jung ◽  
Mok Soon Kim ◽  
Won Yong Kim
Keyword(s):  
Compressive Strength ◽  
Flow Stress ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Volume Fraction ◽  
Eutectic Reaction ◽  
Initial Strain Rate ◽  
Chemical Compositions ◽  
Alloying Effect ◽  
The Given

Two atomized alloy powders, those chemical compositions are Al-10Si-5Fe-1Zr and Al- 10Si-5Fe-4Cu-2Mg-1Zr, were pre-compacted by cold pressing with 350MPa and subsequently hot forged at temperatures ranging from 653K to 845K and at an initial strain rate of 10-2/s in order to produce bulk cylindrical type alloys with the diameter of 10 mm. The addition of Cu and Mg into the present alloy causes a decrease in the eutectic reaction temperature of Al-10Si-5Fe-1Zr alloy from 841K to 786K and results in a decrease of flow stress at the given forging temperature. TEM observation revealed that in addition to Al-Fe based intermetallics, Al2Cu and Al2CuMg intermetallics appeared to display the alloying effect additionally. The volume fraction of intermetallic dispersiods increased by the addition of Cu and Mg. Compressive strength of the present alloys was closely related to the volume fraction of intermetallic dispersoids.

scholarly journals Mechanical Behavior of Cemented Sand Reinforced with Different Polymer Fibers

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Xiangfeng Lv ◽  
Xiaohui Yang ◽  
Hongyuan Zhou ◽  
Shuo Zhang
Keyword(s):  
Compressive Strength ◽  
Mechanical Behavior ◽  
Brittle Failure ◽  
Unconfined Compressive Strength ◽  
Polypropylene Fiber ◽  
Ductile Failure ◽  
Polymer Fibers ◽  
Chemical Compositions ◽  
Peak Strain ◽  
Cemented Sand

In this study, the specimens of cemented sand were prepared by reinforcing it separately with different contents (0.5%, 1.0%, 1.5%, and 2.0%) of three different polymer fibers (polyamide, polyester, and polypropylene) prepared as filaments of different lengths (6, 9, and 12 mm). Then, these specimens were tested, and the improvement effects of the three fibers on the engineering-mechanical behavior of the cemented sand were analyzed and compared. The different microstructures and chemical compositions of the fiber-reinforced cemented sand specimens were investigated using electron microscopy and X-ray diffraction. Compression tests were performed to obtain the stress-strain curves of the specimens. Comparative analysis was performed on the variation patterns of the mechanical parameters (such as unconfined compressive strength and peak strain) of the specimens. Quantitative analysis was performed on the effect of fiber content and fiber filament length on the failure mode of the specimens. It was shown that the inclusion of fibers led to a change from brittle failure to ductile failure. The macro- and microexperimental results revealed that polypropylene fiber had the best improvement effect on the mechanical behavior of the cemented sand, followed by polyester fiber and polyamide fiber. In particular, the cemented sand specimen reinforced with 1.5% polypropylene fiber prepared as 9 mm length filaments had a brittleness index of 0.0578, exhibited ductile failure (in contrast to the brittle failure of the nonreinforced cemented sand), and yielded the highest unconfined compressive strength and shear strength among the specimens.

Temperature and Strain Rate Effects on Mechanical Behavior of a PMMA

2007 ◽  
Vol 340-341 ◽  
pp. 1079-1084 ◽  
Author(s):  
Tao Suo ◽  
Yu Long Li ◽  
Yuan Yong Liu
Keyword(s):  
Flow Stress ◽  
High Strain Rate ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
High Strain ◽  
Strain Range ◽  
Testing Temperature ◽  
Strain Rate Effects ◽  
Rate Effects ◽  
Increasing Temperature

In this paper, the mechanical behavior of a PMMA used as the windshield of aircraft was tested. The experiments were finished under two quasi-static strain rates and a high strain rate with the testing temperature from 299K to 373K. The results show that the mechanical property of this PMMA depends heavily on the testing temperature. The Young’s modulus and flow stress were found to decrease with increasing temperature at low strain rate. At the strain rate of 10-1 1/s, strain softening was observed under all experiment temperatures. At high strain rate, with the temperature increasing, the flow stress decreases remarkably while the failure strain increases, and the strain soften was also observed at the temperature above 333K. Comparing the experiments results at same temperature, it was found the flow stress increases with the rising strain rate. The predictions of the mechanical behavior using the ZWT theoretical model have a good agreement with experimental results in the strain range of 8%.

Sensitivity Analysis of the Material Flow Stress in Machining

Manufacturing ◽  
2003 ◽  
Author(s):  
Ning Fang
Keyword(s):  
Sensitivity Analysis ◽  
Flow Stress ◽  
Aluminum Alloys ◽  
Strain Rate ◽  
Strain Hardening ◽  
Material Flow ◽  
Chemical Compositions ◽  
Wide Range ◽  
Strain Rate Hardening ◽  
Factor Governing

Among the effects of strain hardening, strain-rate hardening, and temperature softening, it has long been argued about which effect is predominant in governing the material flow stress in machining. This paper compares four material constitutive models commonly employed, including Johnson-Cook’s model, Oxley’s model, Zerilli-Armstrong’s model, and Maekawa et al.’s model. A new quantitative sensitivity analysis of the material flow stress is performed based on Johnson-Cook’s model covering a wide range of engineering materials, including plain carbon steels with different carbon contents, alloyed steels, aluminum alloys with different chemical compositions and heat treatment conditions, copper and copper alloys, iron, nickel, tungsten alloys, etc. It is demonstrated that the first predominant factor governing the material flow stress is either strain hardening or thermal softening, depending on the specific work material employed and the varying range of temperatures. Strain-rate hardening is the least important factor governing the material flow stress, especially when machining aluminum alloys.

Hot Deformation Behavior and Microstructural Evolution of Mg-Nd-Zn-Zr Magnesium Alloy

2013 ◽  
Vol 747-748 ◽  
pp. 320-326 ◽  
Author(s):  
Wen Xiang Wu ◽  
Li Jin ◽  
Jie Dong ◽  
Zhen Yan Zhang ◽  
Wen Jiang Ding
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Grain Boundaries ◽  
Microstructural Evolution ◽  
Hot Deformation ◽  
Fine Particles ◽  
Volume Fraction ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Average Size

The hot deformation behaviors and microstructural evolution of Mg-3.0Nd-0.2Zn-0.4Zr (wt. %, NZ30K) alloy were investigated by means of the isothermal hot compression tests at temperatures of 350-500 °C with strain rates of 0.001, 0.01, 0.1 and 1s-1. The results showed that the flow stress increased to a peak and then decreased which showed a dynamic flow softening. The flow stress behavior was described by the hyperbolic sine constitutive equation with an average activation energy of 193.8 kJ/mol. The average size of dynamically recrystallized grains of hot deformed NZ30K alloy was reduced by increasing the strain rate and/or decreasing the deformation temperature. A large amount of fine particles precipitated in the grains interior and at the grain boundaries when heated to the compression temperatures and soaked for 5min below 450 °C. However, the volume fraction of particles decreased significantly when soaked for 5 min at 500 °C, and the coarse particles precipitated mainly at the grain boundaries. Hot deformation at the temperature of 500 °C around and at the strain rate range of 0.1s-1 was desirable for NZ30K alloy.

scholarly journals Deformation Behavior and Dynamic Recrystallization of Mg-1Li-1Al Alloy

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1696
Author(s):  
Xiaoyan Feng ◽  
Xue Pang ◽  
Xu He ◽  
Ruihong Li ◽  
Zili Jin ◽  
...  
Keyword(s):  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Volume Fraction ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Avrami Equation ◽  
Uniaxial Compression Test ◽  
Hot Workability ◽  
The Relationship

In this paper, the hot workability of Mg-1Li-1Al (LA11) alloy is assessed through a uniaxial compression test in a temperature range from 200 to 400 °C and a strain rate, έ, of 1–0.01 s−1. The present study reveals that flow stress increases when the strain rate increases and deformation temperature decreases. Based on the hyperbolic sine equation, the flow stress constitutive equation of this alloy under high-temperature deformation is established. The average activation energy was 116.5 kJ/mol. Avrami equation was employed to investigate the dynamic recrystallization (DRX). The DRX mechanism affected by the deformation conditions and Zener–Hollomon parameters is revealed. Finally, the relationship between DRX volume fraction and deformation parameter is verified based on microstructure evolution, which is consistent with the theoretical prediction.

Dynamic Mechanical Behavior of Two Fiber-Reinforced Composites

2012 ◽  
Vol 525-526 ◽  
pp. 261-264
Author(s):  
Y.Z. Guo ◽  
X. Chen ◽  
Xi Yun Wang ◽  
S.G. Tan ◽  
Z. Zeng ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Rate Dependent ◽  
Dynamic Loadings ◽  
Axial Splitting

The mechanical behavior of two composites, i.e., CF3031/QY8911 (CQ, hereafter in this paper) and EW100A/BA9916 (EB, hereafter in this paper), under dynamic loadings were carefully studied by using split Hopkinson pressure bar (SHPB) system. The results show that compressive strength of CQ increases with increasing strain-rates, while for EB the compressive strength at strain-rate 1500/s is lower then that at 800/s or 400/s. More interestingly, most of the stress strain curves of both of the two composites are not monotonous but exhibit double-peak shape. To identify this unusual phenominon, a high speed photographic system is introduced. The deformation as well as fracture characteristics of the composites under dynamic loadings were captured. The photoes indicate that two different failure mechanisms work during dynamic fracture process. The first one is axial splitting between the fiber and the matrix and the second one is overall shear. The interficial strength between the fiber and matrix, which is also strain rate dependent, determines the fracture modes and the shape of the stress/strain curves.

Study of the Superplasticity of Copper Alloys Used for Solid Cages

2007 ◽  
Vol 551-552 ◽  
pp. 79-83
Author(s):  
F.X. Chen ◽  
He Jun Li ◽  
J.Q. Guo ◽  
Yong Shun Yang ◽  
G.Z. Xu
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Copper Alloys ◽  
Maximum Flow ◽  
Initial Strain Rate ◽  
Initial Strain ◽  
Aluminum Bronze ◽  
Cast Aluminum ◽  
Tension And Compression ◽  
Superplasticity Effect

The superplasticity of cast copper alloys used for solid cages is studied by tests of tension and compression in this paper. The results show that cast copper alloys exhibited superplasticity without any pretreatment. Cast aluminum bronze is of superplasticity at the temperatures between 750~800°C with the initial strain rate 1×10-2s-1, the elongation being over 260%. Under the condition of superplasticity compression with the strain rate (1.136~9.091)x10-4s-1 at temperatures between 600~650°C, the cast lead brass presents the superplasticity effect with the maximum flow stress under 2MPa.

The Mechanical Behavior of Zinc During Machining

1995 ◽  
Vol 117 (2) ◽  
pp. 172-178 ◽  
Author(s):  
Robin Stevenson ◽  
David A. Stephenson
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Feed Rate ◽  
Cutting Forces ◽  
Material Flow ◽  
Cutting Tool ◽  
Cutting Conditions ◽  
Extrapolation Method ◽  
Compression Tests

It is well known that a nonzero force is obtained when cutting forces measured at different feed rates but otherwise constant cutting conditions are extrapolated to zero feed rate. In the literature, this nonzero intercept has been attributed to a ploughing effect associated with the finite sharpness of the cutting tool. However, the standard extrapolation method does not account for other variables such as strain, strain rate and temperature which also vary with feed rate and influence the work material flow stress. In this paper, the apparent flow stresses measured in high and low speed machining tests on zinc are compared with the flow stresses measured in compression tests. The results show that the flow stress measured in cutting is consistent with that measured in compression when all deformation variables are properly accounted for and that, contrary to the results obtained using the extrapolation approach, the ploughing force is negligible.

Mechanical property and dislocation dynamics of GaAsP alloy semiconductor

1989 ◽  
Vol 4 (2) ◽  
pp. 361-365 ◽  
Author(s):  
Ichiro Yonenaga ◽  
Koji Sumino ◽  
Gunzo Izawa ◽  
Hisao Watanabe ◽  
Junji Matsui
Keyword(s):  
Mechanical Property ◽  
Flow Stress ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Dynamic Characteristics ◽  
Collective Motion ◽  
Compound Semiconductors ◽  
Dislocation Dynamics ◽  
Compressive Deformation

The mechanical behavior of GaAsP alloy semiconductor was investigated by means of compressive deformation and compared with those of GaAs and GaP. The nature of collective motion of dislocations during deformation was determined by strain-rate cycling tests. The dynamic characteristics of dislocations in GaAsP were found to be similar to those in elemental and compound semiconductors such as Si, Ge, GaAs, and GaP. An alloy semiconductor has a component of the flow stress that is temperature-insensitive and is absent in compound semiconductors.

scholarly journals Influence of SiC Content on Microstructure, Dislocation Density and Mechanical Behavior of Cu/SiC Composite

2022 ◽  
Vol 24 (1) ◽  
pp. 186-200
Author(s):  
H. A. EL-Fattah ◽  
◽  
M.A. Metwally ◽  
M. M. Sadawy ◽  
I .G.El- Batanony ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Mechanical Behavior ◽  
Volume Fraction ◽  
Percentage Increase ◽  
Sintering Process ◽  
Xrd Diffraction ◽  
Microstructure Examination ◽  
Sic Composites ◽  
The Impact ◽  
Pure Cu

The present investigation has examined the impact of micro-SiC on microstructure, dislocation and mechanical behavior of Cu/SiC composite. The micro-composite samples have been fabricated under a constant pressure (480 MPa) and sintered temperature (860oC) for 2 h. The sintering process was performed under argon gas. The microstructure examination was conducted using SEM/EDS and XRD diffraction. The SiC contents were 0, 5, 10,15,20,25 and 30 volume fraction. The outcomes showed that the density was significantly decreased with an increase of silicon carbide content. The relative densities of Cu and Cu/SiC composites was ranged from 91.24% to 83.56% for pure Cu and Cu/30 vol%SiC composites. The copper crystallite size was reduced with growing SiC content while the hardness, ultimate and yield compressive strength increased with increment of SiC volume fraction to 20% vol. The values of hardness, ultimate and yield compressive strength increased to 231 HV,343 and 176 N/mm2 , respectively for the composite sample containing 20% SiC particles with a percentage increase of 75%,26.6% and 57.2% compared with pure Cu.

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