scholarly journals Thermomechanical Processing of AZ31-3Ca Alloy Prepared by Disintegrated Melt Deposition (DMD)

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 647
Author(s):  
Kamineni Pitcheswara Rao ◽  
Kalidass Suresh ◽  
Yellapregada Venkata Rama Krishna Prasad ◽  
Manoj Gupta
Keyword(s):  
Hot Deformation ◽  
Thermomechanical Processing ◽  
Flow Instability ◽  
Shear Bands ◽  
Secondary Phase ◽  
Az31 Alloy ◽  
Strain Rate Range ◽  
Deformation Mechanisms ◽  
Processing Route ◽  
Melt Deposition

Mg-3Zn-1Al (AZ31) alloy is a popular wrought alloy, and its mechanical properties could be further enhanced by the addition of calcium (Ca). The formation of stable secondary phase (Mg,Al)2Ca enhances the creep resistance at the expense of formability and, therefore, necessitates the establishment of safe working window(s) for producing wrought products. In this study, AZ31-3Ca alloy has been prepared by the disintegrated melt deposition (DMD) processing route, and its hot deformation mechanisms have been evaluated, and compared with similarly processed AZ31, AZ31-1Ca and AZ31-2Ca magnesium alloys. DMD processing has refined the grain size to 2–3 μm. A processing map has been developed for the temperature range 300–450 °C and strain rate range 0.0003–10 s−1. Three working domains are established in which dynamic recrystallization (DRX) readily occurs, although the underlying mechanisms of DRX differ from each other. The alloy exhibits flow instability at lower temperatures and higher strain rates, which manifests as adiabatic shear bands. A comparison of the processing maps of these alloys revealed that the hot deformation mechanisms have not changed significantly by the increase of Ca addition.

Hot Deformation Behavior during the Hot Compression of AZ31 Alloy

2010 ◽  
Vol 139-141 ◽  
pp. 545-548 ◽  
Author(s):  
Shu Li Sun ◽  
Min Gang Zhang ◽  
Wen Wu He ◽  
Jun Qi Zhou ◽  
Gang Sun
Keyword(s):  
Hot Deformation ◽  
Deformation Behavior ◽  
Flow Instability ◽  
Strain Curve ◽  
Az31 Alloy ◽  
Hot Compression ◽  
Instability Criterion ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
Hollomon Parameter

The hot deformation behavior of as-cast AZ31 magnesium alloys have been investigated at 200~400°C and strain rates 0.001~1s-1 by means of hot compression tests on a Gleeble-1500D thermal-mechanical simulator. We have analyzed the flow stress-strain curve and presented the constitutive equation by calculating stress exponent, activation energy and Zemer-Hollomon parameter. Then, the processing map of AZ31 alloys has been developed based on the dynamic material model theories and Prasad instability criterion. The flow instability domain is observed at lower temperature and the larger power dissipation rate is emerging at 300~400°C. We have analyzed the corresponding deformation microstructures and it is characteristic of dynamic recrystallization. These results have shown that AZ31 alloy has good workability at 300~400°C and lower strain rate.

Hot Deformation Behavior of Ti-6Al-4V Alloy with a Transitional Microstructure in the Isothermal Hot Compression

2014 ◽  
Vol 1019 ◽  
pp. 273-279 ◽  
Author(s):  
Yong Xu ◽  
Xiang Jie Yang ◽  
Xiong Xin Jiang ◽  
Yi He ◽  
Dan Ni Du
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Flow Instability ◽  
Testing Machine ◽  
Shear Bands ◽  
Hot Deformation Behavior ◽  
Factors Affecting ◽  
Working Region ◽  
Gleeble 3500

The hot deformation behavior of Ti-6Al-4V alloy with transitional microstructure over temperature 800°C~950°C and strain rate ranges of 0.001~10s-1 has been studied by Gleeble-3500 hot working simulation testing machine. The flow softening of stress-strain curves is resulted from the spheroidization of transitional microstructure, dynamic recrystallization and superplasticity. Both temperature and strain rate are important factors affecting the deformation behavior. Flow instability induced by adiabatic shear bands occurs at 800-880°Cand 0.32-10 s-1. With the increasing of strain rate and decreasing of temperature, the degree of strain localization increases. The optimum working region of Ti-6Al-4V alloy with a transitional microstructure is at 820-910°C and 0.001-0.1 s-1.

Hot Deformation and Processing Maps of 7005 Aluminum Alloy

2014 ◽  
Vol 33 (4) ◽  
pp. 369-375 ◽  
Author(s):  
Mingliang Wang ◽  
Peipeng Jin ◽  
Jinhui Wang
Keyword(s):  
Strain Rate ◽  
Power Dissipation ◽  
Flow Instability ◽  
Shear Bands ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Instability Map ◽  
Flow Stress Data ◽  
Corrected Flow ◽  
Microstructural Examination

AbstractThe deformation behavior of 7005 alloy was studied by hot compression tests. The processing map was constructed by superimposing the instability map over the power dissipation map at a strain of 0.7 using the corrected flow stress data to eliminate the effect of friction. Microstructural examination was performed for validation. It can be found that the flow stresses increase with the decrease of deformation temperature or the increase of strain rate. At the relatively high strain rates, the material exhibits flow instability manifesting as adiabatic shear bands or flow localization. A large volume of coarse precipitations distributing in the grain boundaries in one of the peak efficiency domains: 275–325 °C/0.0005–0.001 s−1, which may result in inter-granular corrosion and spalling layer, should be avoided in the final deformed alloy. The optimum hot working domain is the temperature range of 400–450 °C and strain rate range of 0.0005–0.005 s−1, at which DRX is identified.

Characterization of hot deformation behavior of Ti–3Al–5Mo–4.5V alloy with a martensitic starting microstructure

2017 ◽  
Vol 02 (03) ◽  
pp. 1750011
Author(s):  
Chunjie Xiang ◽  
Yong Liu ◽  
Bin Liu ◽  
Yuankui Cao ◽  
Ziyang Gan
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Thermomechanical Processing ◽  
Processing Parameters ◽  
Strain Rate Range ◽  
Unstable Flow ◽  
Hot Deformation Behavior ◽  
Temperature Range ◽  
Average Grain Size

The hot deformation behavior of Ti–3Al–5Mo–4.5V alloy with an [Formula: see text] martensitic microstructure was studied in the temperature range of 700–1000[Formula: see text]C and strain rates range of 0.001–[Formula: see text] up to a height reduction of 50%. The results show that an ultrafine equiaxed microstructure with an average grain size of [Formula: see text] were successfully produced through thermomechanical processing of a martensitic starting microstructure. A processing map was successfully constructed and provides appropriate processing parameters for hot deformation which are located in the temperature range of 700–800[Formula: see text]C and the low strain rate range of 0.001–[Formula: see text]. The instability domain mainly occurs at the strain rate higher than [Formula: see text] for the whole deformation temperature, which should be avoided during practice. The flow softening mechanism of the alloy is determined to be continuous dynamic recrystallization and the unstable flow is caused by the macro-fracture and flow localization.

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.

The Effect of Secondary Metalworking Processes on Susceptibility of Aircraft to Catastrophic Failures and Prevention Methods

2013 ◽  
Vol 58 (4) ◽  
pp. 1207-1212
Author(s):  
E.S. Dzidowski
Keyword(s):  
Dynamic Recovery ◽  
Fatigue Cracks ◽  
Shear Bands ◽  
Adiabatic Shear ◽  
Deformation Mechanisms ◽  
Processing Maps ◽  
Adiabatic Shear Bands ◽  
Flow Localization ◽  
Catastrophic Failures ◽  
Prevention Methods

Abstract The causes of plane crashes, stemming from the subcritical growth of fatigue cracks, are examined. It is found that the crashes occurred mainly because of the negligence of the defects arising in the course of secondary metalworking processes. It is shown that it is possible to prevent such damage, i.e. voids, wedge cracks, grain boundary cracks, adiabatic shear bands and flow localization, through the use of processing maps indicating the ranges in which the above defects arise and the ranges in which safe deformation mechanisms, such as deformation in dynamic recrystallization conditions, superplasticity, globularization and dynamic recovery, occur. Thanks to the use of such maps the processes can be optimized by selecting proper deformation rates and forming temperatures.

scholarly journals The Effect of α-Al(MnCr)Si Dispersoids on Activation Energy and Workability of Al-Mg-Si-Cu Alloys during Hot Deformation

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xiaoguo Wang ◽  
Jian Qin ◽  
Hiromi Nagaumi ◽  
Ruirui Wu ◽  
Qiushu Li
Keyword(s):  
Activation Energy ◽  
Aluminum Alloys ◽  
Constitutive Equation ◽  
Hot Deformation ◽  
Flow Instability ◽  
Void Formation ◽  
Activation Energies ◽  
Compression Tests ◽  
Softening Mechanism ◽  
Dynamic Softening

The hot deformation behaviors of homogenized direct-chill (DC) casting 6061 aluminum alloys and Mn/Cr-containing aluminum alloys denoted as WQ1 were studied systematically by uniaxial compression tests at various deformation temperatures and strain rates. Hot deformation behavior of WQ1 alloy was remarkably changed compared to that of 6061 alloy with the presence of α-Al(MnCr)Si dispersoids. The hyperbolic-sine constitutive equation was employed to determine the materials constants and activation energies of both studied alloys. The evolution of the activation energies of two alloys was investigated on a revised Sellars’ constitutive equation. The processing maps and activation energy maps of both alloys were also constructed to reveal deformation stable domains and optimize deformation parameters, respectively. Under the influence of α dispersoids, WQ1 alloy presented a higher activation energy, around 40 kJ/mol greater than 6061 alloy’s at the same deformation conditions. Dynamic recrystallization (DRX) is main dynamic softening mechanism in safe processing domain of 6061 alloy, while dynamic recovery (DRV) was main dynamic softening mechanism in WQ1 alloy due to pinning effect of α-Al(MnCr)Si dispersoids. α dispersoids can not only resist DRX but also increase power required for deformation of WQ1 alloy. The microstructure analysis revealed that the flow instability was attributed to the void formation and intermetallic cracking during hot deformation of both alloys.

The Constitutive Model for High Temperature Flow Behavior of SiC/6168Al Composite

2015 ◽  
Vol 1089 ◽  
pp. 37-41
Author(s):  
Jiang Wang ◽  
Sheng Li Guo ◽  
Sheng Pu Liu ◽  
Cheng Liu ◽  
Qi Fei Zheng
Keyword(s):  
Constitutive Model ◽  
Hot Deformation ◽  
Flow Behavior ◽  
Type Equation ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Stress Strain ◽  
Hollomon Parameter ◽  
Proposed Model ◽  
Relationship Of

The hot deformation behavior of SiC/6168Al composite was studied by means of hot compression tests in the temperature range of 300-450 °C and strain rate range of 0.01-10 s-1. The constitutive model was developed to predict the stress-strain curves of this composite during hot deformation. This model was established by considering the effect of the strain on material constants calculated by using the Zenter-Hollomon parameter in the hyperbolic Arrhenius-type equation. It was found that the relationship of n, α, Q, lnA and ε could be expressed by a five-order polynomial. The stress-strain curves obtained by this model showed a good agreement with experimental results. The proposed model can accurately describe the hot flow behavior of SiC/6168Al composite, and can be used to numerically analyze the hot forming processes.

scholarly journals PRELIMINARY INVESTIGATION OF BILLET PROCESSING ROUTE ON MICROSTRUCTURE, TEXTURE AND FATIGUE RESPONSE OF Ti834 FORGED DISC PRODUCTS

2020 ◽  
Vol 321 ◽  
pp. 11031
Author(s):  
B. Fernandez-Silva ◽  
B. P. Wynne ◽  
M. Jackson ◽  
M. Bodie ◽  
K. Fox
Keyword(s):  
Fatigue Life ◽  
Texture Analysis ◽  
Fatigue Fracture ◽  
Thermomechanical Processing ◽  
Preliminary Investigation ◽  
Processing Route ◽  
Bimodal Microstructure ◽  
Primary Alpha ◽  
Dwell Fatigue ◽  
Beta Matrix

Non-standard processing routes for the manufacture of industrial scale Ti834 billet have been undertaken to investigate their effect on macrozones in final forged product. Microstructure, texture and dwell fatigue fracture surfaces were characterised from forged disc samples fabricated from these new billets. All processing routes showed a bimodal microstructure consisting of 25pct of primary alpha grains in a transformed beta matrix. Texture analysis has revealed variations in the presence and size of macrozones with relatively weak textures. Quasi-cleavage facets were present in all dwell fatigue samples although the fatigue life was doubled for the sample whose thermomechanical processing has the highest imposed strain.

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