Temperature and Strain Rate Dependence of Deformation Microstructures of AZ31 Magnesium Alloy under Uniaxial Tension

2011 ◽  
Vol 217-218 ◽  
pp. 93-96 ◽  
Author(s):  
Wan Peng Deng ◽  
Zhan Feng Gao ◽  
Xiao Wu Li
Keyword(s):  
Strain Rate ◽  
Room Temperature ◽  
Tensile Deformation ◽  
Flow Behavior ◽  
Strain Rate Range ◽  
Mg Alloy ◽  
Rate Range ◽  
Deformation Twins ◽  
Az31 Mg Alloy ◽  
Increasing Temperature

The tensile deformation microstructures of an extruded AZ31 Mg alloy were examined at temperatures ranging from room temperature to 250°C over a strain rate range from 10-4 s-1 to 10-2 s-1. It is found that the strain rate has an enhanced effect on the tensile flow behavior of AZ31 Mg alloy with increasing temperature, which is closely related to the changes of deformation microstructures. The tensile deformation of AZ31 Mg alloy is mainly accommodated by twinning and slipping at room temperature and 100°C, and the amount of deformation twins reduces with increasing temperature and decreasing strain rate. However, discontinuous dynamic recrystallization (DRX) occurs primarily at grain boundaries, and nearly no deformation twins form, as the temperature is as high as 250°C. With decreasing strain rate, more significant DRX takes place with an increasing DRX grain size. The tensile deformation of AZ31 Mg alloy at 250°C is thus primarily controlled by slipping and DRX.

Strain Rate Sensitivity of Ultrafine-Grained CP-Ti Processed by ECAP at Room Temperature

2010 ◽  
Vol 667-669 ◽  
pp. 707-712 ◽  
Author(s):  
Xiao Yan Liu ◽  
Xi Cheng Zhao ◽  
Xi Rong Yang
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Ultrafine Grained ◽  
Die Set ◽  
Increasing Temperature ◽  
Cp Ti

Ultrafine-grained (UFG) commercially pure (CP) Ti with a grain size of about 200 nm was produced by ECAP up to 8 passes using route BC at room temperature. For ECAP processing a proper die set was designed and constructed with an internal channel angle Φ of 120° and an outer arc of curvature Ψ of 20°. Strain rate sensitivity of UFG CP-Ti and CG CP-Ti were investigated by compression tests in the temperature range of 298~673K and strain rate range of 10-4~100s-1 using Gleeble simulator machine. Evolution of the microstructure during compression testing was observed using optical microscopy (OM) and transmission electron microscopy (TEM). Strain rate sensitivity value m of the UFG CP-Ti has been measured and is found to increase with increasing temperature and decreasing strain rate, and is enhanced compared to that of CG CP-Ti. Result of the deformation activation energy determination of UFG CP-Ti indicates that the deformation mechanism in UFG CP-Ti is correlated to the grain boundaries.

Characterization of Hot Deformation Behavior of Zr-4 Alloy in Material Application Area

2012 ◽  
Vol 578 ◽  
pp. 202-205
Author(s):  
Guo Qing Lin
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Flow Behavior ◽  
Strain Rate Range ◽  
Processing Maps ◽  
Peak Efficiency ◽  
Hot Deformation Behavior ◽  
Rate Range ◽  
Temperature Range

The hot deformation behavior of Zr-4 alloy was studied in the temperature range 650-900°C and strain rate range 0.005-50s-1 using processing maps. The processing maps revealed three domains: the first occurs in the temperature range 780-820°C and strain rate range 0.005-0.05s-1, and has a peak efficiency of 45% at 790°C and 0.005s-1; the mechanism is the dynamic recrystallization. The second occurs in the temperature range greater than 900°C and strain rate range 0.05-0.8s-1, and has a peak efficiency of 40% at 900°C and 0.5s-1, which are the domains of dynamic recovery. In addition, the instability zones of flow behavior can also be recognized by the maps in the temperature range 650-780°C and strain rate range 0.01-0.1s-1, which should be strictly avoided in the processing of the material. Zr-4 alloy is the material for pressure tube applications in nuclear reactors and has better strength and a lower rate of hydrogen uptake compared to other materials under similar service conditions.

Research on the Semi-Solid Compressive Deformation Behavior of Ti-7Cu Alloy

2016 ◽  
Vol 35 (1) ◽  
pp. 29-35 ◽  
Author(s):  
Yongnan Chen ◽  
Chuang Luo ◽  
Jiao Wang ◽  
Yongqing Zhao ◽  
Hong Chen
Keyword(s):  
Titanium Alloy ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Strain Rate Range ◽  
Rate Range ◽  
Solid Deformation ◽  
Pile Up ◽  
Compressive Testing ◽  
Semi Solid ◽  
Increasing Temperature

AbstractThe semi-solid deformation behavior of Ti-7Cu titanium alloy in the temperature range of 1,223 K to 1,473 K and strain rate range of 0.005 to 5 s−1 have been investigated by hot compressive testing. The results show that the maximum and stability stresses decrease with decreasing strain rate and increasing temperature. A yielding occurred to the alloy at a higher strain rate under all experimental temperatures. The flow behaviors were described by a constitutive equation based on the Arrhenius equations and the deformation activate energies is also calculated. By comparing with microstructure of the solid deformation, the liquid in semi-solid deformation can overcome the restriction of the movement of solid particle, which reduced the dislocation pile-up during deformation and caused low deformation resistant stress.

A Comparative Study on Johnson Cook, Modified Zerilli–Armstrong and Arrhenius-Type Constitutive Models to Predict High-Temperature Flow Behavior of Ti–6Al–4V Alloy in α + β Phase

2016 ◽  
Vol 35 (3) ◽  
pp. 297-307 ◽  
Author(s):  
Jun Cai ◽  
Kuaishe Wang ◽  
Yingying Han
Keyword(s):  
High Temperature ◽  
Comparative Study ◽  
Strain Rate ◽  
Good Description ◽  
Flow Behavior ◽  
Strain Rate Range ◽  
Type Model ◽  
Rate Range ◽  
Β Phase ◽  
Average Absolute Relative Error

AbstractTrue stress and true strain values obtained from isothermal compression tests over a wide temperature range from 1,073 to 1,323 K and a strain rate range from 0.001 to 1 s–1 were employed to establish the constitutive equations based on Johnson Cook, modified Zerilli–Armstrong (ZA) and strain-compensated Arrhenius-type models, respectively, to predict the high-temperature flow behavior of Ti–6Al–4V alloy in α + β phase. Furthermore, a comparative study has been made on the capability of the three models to represent the elevated temperature flow behavior of Ti–6Al–4V alloy. Suitability of the three models was evaluated by comparing both the correlation coefficient R and the average absolute relative error (AARE). The results showed that the Johnson Cook model is inadequate to provide good description of flow behavior of Ti–6Al–4V alloy in α + β phase domain, while the predicted values of modified ZA model and the strain-compensated Arrhenius-type model could agree well with the experimental values except under some deformation conditions. Meanwhile, the modified ZA model could track the deformation behavior more accurately than other model throughout the entire temperature and strain rate range.

Fracture Behavior Transition by Change of Strain Rate in Dislocation-Induced Si Steels

2012 ◽  
Vol 706-709 ◽  
pp. 2187-2192 ◽  
Author(s):  
Takashi Mizuguchi ◽  
Rintaro Ueji ◽  
Hayato Miyagawa ◽  
Yasuhiro Tanaka ◽  
Kazunari Shinagawa
Keyword(s):  
Strain Rate ◽  
Dislocation Structure ◽  
Fracture Behavior ◽  
Room Temperature ◽  
Tensile Deformation ◽  
Tensile Specimen ◽  
Strain Rates ◽  
Deformation Twins ◽  
Transition Strain ◽  
Magnetic Steel

The fracture behavior transition due to the change of strain rate in 5%Si magnetic steel with dislocation microstructures was studied. The Si steel was multi-passed rolled at 800°C to a various reductions up to 50%. The room temperature tensile deformation was conducted at various strain rates from 10-5/s to 100/s. All rolled steels were fractured in ductile manners with local elongation (necking) at slower strain rate. When strain rate was faster, the local elongation disappeared and the fracture manner was turned to brittle. The strain rate at which fracture mechanism changed from ductile to brittle increased with the increasing of the reduction. On the other hand, the almost fully recrystallized Si steel was fractured in the brittle manner at any strain rate and the transition strain rate was not found. The fractured tensile specimen with no local elongations contains deformation twins; whereas these deformation twins were not observed in the fractured specimen with local elongations. This result indicates that dislocation structure evolved during rolling suppressed the twinning and that the dislocation structure is effective for the enhancement of toughness in Si steel.

Flow Behavior and Processing Map of Mg-4Al-3Ca-1.5Zn-1Nd-0.2Mn Magnesium Alloy

2014 ◽  
Vol 915-916 ◽  
pp. 588-592
Author(s):  
Gang Chen ◽  
Wei Chen ◽  
Guo Wei Zhang ◽  
Jing Zhai ◽  
Li Ma
Keyword(s):  
Magnesium Alloy ◽  
Strain Rate ◽  
Processing Map ◽  
Flow Behavior ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Rate Range ◽  
Temperature Range ◽  
Optimal Temperature Range ◽  
Flow Stress Data

Compression tests of Mg-4Al-3Ca-1.5Zn-1Nd-0.2Mn Magnesium alloy as-extruded had been performed in the compression temperature range from 200°C to 350°C and the strain rate range from 0.001 s1to 1 s1and the flow stress data obtained from the tests were used to develop the power dissipation map, instability map and processing map. The optimum parameters for hot working of the alloy had been determined. According to the processing maps, the most optimal temperature range is 280°C to 350°C and most optimal strain rate range is 0.001 S-1to 1 S-1.

scholarly journals Dynamic Mechanical Behavior and Microstructure Evolution of an Extruded 6013-T4 Alloy at Elevated Temperatures

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 629 ◽  
Author(s):  
Tuo Ye ◽  
Yuanzhi Wu ◽  
Wei Liu ◽  
Bin Deng ◽  
Anmin Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Stress Level ◽  
Microstructure Evolution ◽  
Elevated Temperatures ◽  
Strain Rate Range ◽  
Rate Range ◽  
Dynamic Mechanical Behavior ◽  
Strain And Strain Rate ◽  
Increasing Temperature

The mechanical properties of an extruded 6013-T4 alloy were tested at a temperature range from 25 to 400 °C and strain rate range from 1 × 103 to 5 × 103 s−1. The results demonstrate that the stress level is sensitive to strain rate and temperature. The stress level increases slightly with increasing strain rate and decreases remarkably with increasing temperature. The dislocation and precipitate undergo great changes. When deformed at 25 °C, the density of the dislocation increases with strain and strain rate; which leads to a higher stress level. A great number of needle-like precipitates were observed at samples deformed at 200 °C. It is clear that the density of dislocation increases with strain and strain rate. When impacted at 400 °C, the coarser precipitates were found in the specimen; the density of the dislocation increases with strain and strain rate.

Softening Phenomenon during Compression Test in Nanograined Aluminum Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 3489-3492 ◽  
Author(s):  
Se Hyun Ko ◽  
Jin Man Jang ◽  
Won Sik Lee
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloys ◽  
Strain Rate ◽  
Strain Hardening ◽  
Compression Test ◽  
Room Temperature ◽  
Strain Rate Range ◽  
Rate Range ◽  
Cu Alloys ◽  
Deformation Behaviors

Al-Mg and Al-Mg-Cu alloys are known well to reveal superplasticity in tension at high temperatures. In this study, deformation behaviors of those alloys nanograined were investigated under compression test at room temperature. During plastic deformation softening phenomena occurred obviously in nanograined Al-1.5wt%Mg and Al-0.7wt%Mg-1.0wt%Cu alloys while slight strain hardening appeared in nanograined pure Al. These results suggest that the softening strongly depends on composition of alloys. The softening takes place over strain rate range from 10-4 up to 10-1.

Flow Behavior and Workability of a Zn-8Cu-0.2Cr Alloy during Hot Deformation

2012 ◽  
Vol 538-541 ◽  
pp. 1257-1261
Author(s):  
Sheng Li Guo ◽  
Peng Du ◽  
Xiao Ping Wu ◽  
De Fu Li
Keyword(s):  
Constitutive Equation ◽  
Strain Rate ◽  
Hot Deformation ◽  
Flow Instability ◽  
Flow Behavior ◽  
Strain Rate Range ◽  
Processing Maps ◽  
Compression Tests ◽  
Rate Range ◽  
Temperature Range

The hot deformation behavior of Zn91.8-Cu8-Cr0.2 (in wt.%) was investigated by means of hot compression tests in the temperature range of 230-380 °C and strain rate range of 0.01 - 10 s-1. The constitutive equation and processing maps were developed. The influence of strain on the flow stress was studied by considering the effect of the strain on material constants. The stress-strain curves obtained by the constitutive equation are in good agreement with experimental results. The proposed constitutive equations can be used for the analysis problem of hot forming processes. The processing maps have exhibited a domain, which is optimum processing window for hot working, in the temperature range of 310 - 380 °C and strain rate range of 0.01-1 s-1 corresponding to the higher efficiency of power dissipation. The large regime of flow instability is observed at high strain rate. The instability regime should be avoided during hot deformation processing.

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