scholarly journals Strain Hardening in an AZ31 Alloy Submitted to Rotary Swaging

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 157
Author(s):  
Zuzanka Trojanová ◽  
Zdeněk Drozd ◽  
Kristýna Halmešová ◽  
Ján Džugan ◽  
Tomáš Škraban ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Strain Hardening ◽  
Work Hardening ◽  
Room Temperature ◽  
Az31 Alloy ◽  
First Order ◽  
Softening Mechanism ◽  
Rotary Swaging ◽  
Magnesium Az31 ◽  
Tension And Compression

An extruded magnesium AZ31 magnesium alloy was processed by rotary swaging (RSW) and then deformed by tension and compression at room temperature. The work-hardening behaviour of 1–5 times swaged samples was analysed using Kocks-Mecking plots. Accumulation of dislocations on dislocation obstacles and twin boundaries is the deciding factor for the strain hardening. Profuse twinning in compression seems to be the reason for the higher hardening observed during compression. The main softening mechanism is apparently the cross-slip between the pyramidal planes of the second and first order. A massive twinning observed at the deformation beginning influences the Hall-Petch parameters.

Study on Compression Behaviour of AZ31 Magnesium Alloy at Room-Temperature

2012 ◽  
Vol 476-478 ◽  
pp. 1960-1964
Author(s):  
Jia Le Sun ◽  
Rui Chun Li ◽  
Gao Feng Quan ◽  
Zhao Ming Liu
Keyword(s):  
Magnesium Alloy ◽  
Strain Hardening ◽  
Room Temperature ◽  
Deformation Behaviour ◽  
Az31 Alloy ◽  
Strain Hardening Exponent ◽  
Surface Cracks ◽  
Compression Properties ◽  
Compression Behaviour ◽  
Az31 Mg Alloy

The microstructure, surface morphology, compression properties, deformation behaviour and strain hardening exponent of as-cast and as-extruded AZ31 Mg alloy after different annealing treatments were investigated. The results show that the compression properties are great different between cast AZ31 alloy and extruded AZ31 alloy. Extruded AZ31 alloy is discontinuous yield and on the surface no signs of damage have been observed; on the contrast, cast AZ31 alloy is continuous yield and shows wavy patterns, and the surface cracks can be easily found. In addition, there is a linear relationship between the strain hardening exponent in first deformation stage and the yield ratio. Further more, the twinning mechanism plays very different role in cast AZ31 alloy and extruded AZ31 alloy.

Deformation of an extruded nickel beryllide between room temperature and 820 °C

1991 ◽  
Vol 6 (12) ◽  
pp. 2653-2659 ◽  
Author(s):  
G.M. Pharr ◽  
S.V. Courington ◽  
J. Wadsworth ◽  
T.G. Nieh
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Elevated Temperature ◽  
Flow Stress ◽  
Strain Hardening ◽  
Room Temperature ◽  
High Temperature Strength ◽  
Compression Tests ◽  
Tension And Compression ◽  
Better Than

The mechanical properties of nickel beryllide, NiBe, have been investigated in the temperature range 20–820 °C. The room temperature properties were studied using tension, bending, and compression tests, while the elevated temperature properties were characterized in compression only. NiBe exhibits some ductility at room temperature; the strains to failure in tension and compression are 1.3% and 13%, respectively. Fracture is controlled primarily by the cohesive strength of grain boundaries. At high temperatures, NiBe is readily deformable—strains in excess of 30% can be achieved at temperatures as low as 400 °C. Strain hardening rates are high, and the flow stress decreases monotonically with temperature. The high temperature strength of NiBe is as good or better than that of NiAl, but not quite as good as CoAl.

Relative Activities of Deformation Modes in AZ31 Magnesium Alloy Predicted by Mesoscopic Crystalline Model

2011 ◽  
Vol 399-401 ◽  
pp. 21-25
Author(s):  
De Liang Yin ◽  
Jin Qiang Liu ◽  
Xin Chen
Keyword(s):  
Magnesium Alloy ◽  
Room Temperature ◽  
Az31 Magnesium Alloy ◽  
Plastic Response ◽  
Hardening Behavior ◽  
Pyramidal Slip ◽  
Proposed Model ◽  
Tension And Compression ◽  
Strain Hardening Behavior ◽  
Deformation Modes

A mesoscopic crystalline model was proposed to quantitatively analyze the relative activities of deformation modes involved in the plastic deformation of an AZ31 magnesium alloy at room temperature. The plastic response of a cast AZ31 magnesium alloy with random texture can be well predicted by this model. It is demonstrated that the remarkable difference of relative activities of <c+a> pyramidal slip should be attributed to the different strain hardening behavior in tension and compression. Further TEM micrographs shows the occurrence of <c+a> pyramidal slip in compression, which confirms the validity of the proposed model.

Influence of Annealing Temperature on Microstructure and Properties of Warm-Rolled AZ31 Magnesium Alloy Sheets

2013 ◽  
Vol 747-748 ◽  
pp. 352-358
Author(s):  
Hua Zhang ◽  
Guang Sheng Huang ◽  
Jin Han Lin ◽  
Li Fei Wang
Keyword(s):  
Magnesium Alloy ◽  
Strain Hardening ◽  
Annealing Temperature ◽  
Az31 Alloy ◽  
Az31 Magnesium Alloy ◽  
Strain Hardening Exponent ◽  
N Value ◽  
Microstructure And Properties ◽  
Different Temperatures ◽  
R Value

Warm-rolled AZ31 alloy sheets were annealed at different temperatures ranging from 150 to 450°C. Effects of annealing temperature on microstructure and properties of warm-rolled AZ31 alloy sheets, especially the formability, were investigated. The results revealed that the Lankford value (r-value) and strain-hardening exponent (n-value) first increased and then became relatively steady with the increase of annealing temperature. The Erichsen value (IE) first increased and then decreased with the increase of annealing temperature and the AZ31 alloy sheets exhibited the highest IE of 3.02 mm when annealing at 250°C, which can be mainly attributed to a larger elongation, a lower r-value and a higher n-value.

scholarly journals Increasing the Lightweight Potential of Composite Cold Forging by Utilizing Magnesium and Granular Cores

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 32
Author(s):  
Robin Gitschel ◽  
Felix Kolpak ◽  
Oliver Hering ◽  
A. Erman Tekkaya
Keyword(s):  
Magnesium Alloy ◽  
Granular Media ◽  
Az31 Alloy ◽  
Cold Forging ◽  
Forming Limit ◽  
Process Route ◽  
Wide Range ◽  
Shear Yield ◽  
Magnesium Az31 ◽  
Hollow Shafts

In this paper a process sequence, that uses forward rod extrusion with cold forged C15 steel cup billets to produce lightweight shafts, is presented. The steel cup billets feature either a lightweight magnesium alloy core or a granular medium core that is removed after forming to obtain hollow shafts without the need of complex tools and highly loaded mandrels. It is shown that composite shafts featuring magnesium cores can be produced for a wide range of extrusion strains. Due to high hydrostic pressures in forward rod extrusion, the forming limit of magnesium at room temperature can be expanded. The observed bond strength between core and sheath is below the shear yield strength of utilized magnesium AZ31 alloy. Hollow shafts are successfully produced with the presented process route by utilizing zirconium oxide beads or quartz sand as a lost core. As the law of constant volume in metal forming is violated by compressible granular media, a simulation approach using a modified Drucker-Prager yield surface to model these materials is validated to provide a tool for efficient process design. Granular cores and magnesium alloy cores offer new possibilities in production of lightweight shafts by means of composite cold forging. Both process variants allow for higher weight savings than composite shafts based on aluminum cores.

scholarly journals The Effect of Short Duration Electric Current on the Quasi-Static Tensile Behavior of Magnesium AZ31 Alloy

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Trung Thien Nguyen ◽  
Thai Vinh Nguyen ◽  
Sung-Tae Hong ◽  
Moon-Jo Kim ◽  
Heung Nam Han ◽  
...  
Keyword(s):  
Flow Stress ◽  
Strain Hardening ◽  
Electric Current ◽  
Electric Energy ◽  
Single Pulse ◽  
Az31 Alloy ◽  
Tensile Behavior ◽  
Magnesium Az31 ◽  
Static Tensile ◽  
Electric Energy Density

The effect of a single pulse of electric current with short duration on the quasi-static tensile behavior of a magnesium AZ31 alloy is experimentally investigated. A single pulse of electric current with duration less than 1 second is applied to the specimen, while the specimen is being deformed in the plastic region under quasi-static tensile loads. After a nearly instant decrease of flow stress at the pulse of electric current, the flow stress shows strain hardening until the failure of the specimen. The experimental result shows that the strain-hardening parameters (the strength coefficient and the strain-hardening exponent) of the hardening curve after the electric current strongly depend on the applied electric energy density (electric energy per unit volume). Empirical expressions are suggested to describe the hardening behavior after the pulse as a function of the electric energy density and are compared with the empirical expressions suggested for advanced high-strength steels.

The Effect of Cold Equal Channel Angular Process on Texture of Magnesium Alloy (AZ31)

2006 ◽  
Vol 510-511 ◽  
pp. 498-501
Author(s):  
Hee Taek Lim ◽  
Jung Hoon Kang ◽  
Jeong Whan Han ◽  
Sun Keun Hwang ◽  
Won Yong Kim
Keyword(s):  
Magnesium Alloy ◽  
Room Temperature ◽  
Plastic Material ◽  
Effective Strain ◽  
Extrusion Direction ◽  
Hot Extrusion ◽  
Az31 Alloy ◽  
New Combination ◽  
Compressive Yield Strength ◽  
Ecap Process

In the present study, we have attempted to refine a microstructure of conventional AZ31 magnesium alloy using a new combination process including hot extrusion followed by a cold equal channel angular pressing (ECAP). ECAP die was specially designed with an inner die corner angle of 135 degree, the fillet angle of 45 degree and dimensional thermo-coupled elastro-plastic material model in order to understand the change of stress and strain of the deformed material after a cold ECAP. ECAP for the AZ31 alloy, which was extruded in the extrusion ratio 20 to 1 and heat-treated at 623K, was successfully carried out at room temperature. The uniform shear band obtained from experiment was well matched with the zone of effective strain more than 0.533 estimated from calculation. On the basis of the results, it is suggested that the room temperature ECAP makes microstructure to be refined and the basal plane to be rotated slightly from extrusion direction to axis direction. Compressive yield strength of AZ31 alloy can be enhanced up to twice in applying ECAP process. Hall-Petch relations do not fit to the experimental data This can be ascribed to the texture effect. Room temperature ECAP process is very promising in improving mechanical properties of AZ31 alloy in terms of grain refinement and texture control.

scholarly journals Microstructure and Selected Properties of Cr3C2–NiCr Coatings Obtained by HVOF on Magnesium Alloy Substrates

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2775 ◽  
Author(s):  
Ewa Jonda ◽  
Leszek Łatka ◽  
Wojciech Pakieła
Keyword(s):  
Magnesium Alloy ◽  
Az31 Alloy ◽  
Composition Analysis ◽  
High Velocity Oxygen Fuel ◽  
Instrumented Indentation ◽  
Hvof Spraying ◽  
Alloy Substrate ◽  
Magnesium Az31 ◽  
Abrasive Erosion ◽  
Oxygen Fuel

In present work the Cr3C2–NiCr coating was deposited on magnesium alloy substrate with high velocity oxygen fuel (HVOF) spraying. The microstructure of the samples has been characterized by means of electron microscopy, SEM and phase composition analysis carried out. The porosity of coatings has been also estimated. Finally, tests of selected mechanical properties, such as instrumented indentation, abrasive erosion have been performed. The results of the investigations confirmed that dense, homogeneous and well-adhered Cr3C2–NiCr cermet coating is possible to obtain onto the magnesium AZ31 alloy substrate. Moreover, the coatings exhibit high resistance to erosion.

Microstructural Evolution and Mechanical Behavior of AZ31 Magnesium Alloy Sheets with Li Addition

2015 ◽  
Vol 816 ◽  
pp. 399-403
Author(s):  
Qing Shan Yang ◽  
Bin Jiang ◽  
Wei Jiang ◽  
Bo Song ◽  
Su Qing Luo ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Mechanical Behavior ◽  
Room Temperature ◽  
Mechanical Performance ◽  
Texture Evolution ◽  
Tensile Tests ◽  
Az31 Alloy ◽  
Az31 Magnesium Alloy ◽  
Basal Texture ◽  
X Ray Diffraction

AZ31 magnesium alloy and its alloy with 5% lithium were extruded to 1mm in thickness sheets at 380 oC with extrusion ratio of 101. Microstructure evolution and mechanical behavior of the extruded Mg alloy sheets were examined. The microstructure and texture evolution were investigate by electronic backscattered diffraction (EBSD) and X-ray diffraction (XRD). Mechanical performance was carried out by tensile tests at room temperature. In addition, the evolution of neutral layer and microstructure was also examined by V-bending. It was found that Li addition resulted in the strong divergence of the grain orientation. (0002) basal texture of AZ31 alloy sheets with 5% lithium has been weakened. The room temperature ductility of these textural sheets was enhanced owing to the tilted weak basal texture. Moreover, it exhibits superior ductility during V-bending process at room temperature.

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