scholarly journals Hot deformation behavior of nano-Al2O3-dispersion-strengthened Cu20W composite

2021 ◽  
Vol 28 (1) ◽  
pp. 500-509
Author(s):  
Junchao An ◽  
Meng Zhou ◽  
Baohong Tian ◽  
Yongfeng Geng ◽  
Yijie Ban ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Thermal Deformation ◽  
Dynamic Recovery ◽  
Optical Microscope ◽  
Strain Rates ◽  
Sintering Process ◽  
Optimal Processing ◽  
Transmission Electron ◽  
Hot Pressing Sintering ◽  
The Relationship

Abstract Nano-Al2O3 dispersion-strengthened Cu20W composite was fabricated by vacuum hot-pressing sintering process. The electrical conductivity, relative density, and Brinell hardness were tested, respectively. The gleeble-1500D thermomechanical simulator was used to conduct isothermal compression with strain rates ranging from 0.001 to 10 s−1 and the temperatures ranging from 650 to 950°C. The microstructure of the Cu–Al2O3/20W composite was observed using an optical microscope and a transmission electron microscope, and the true stress–strain curves were analyzed. In addition, the influence of the nano-Al2O3 and tungsten on the thermal deformation process of the composite was analyzed. The relationship and interaction among work hardening, dynamic recovery, and dynamic recrystallization were illustrated. The results show that nano-Al2O3 particles pin dislocations and inhibit dynamic recovery and dynamic recrystallization. Consequently, the Cu–Al2O3/20W composite has typical dynamic recovery characteristics. Hence, the Cu–Al2O3/20W composite possesses outstanding high-temperature performance. The optimal processing domain of the Cu–Al2O3/20W composite ranged from 760 to 950°C with strain rates ranging from 0.01 to 0.1 s−1. Furthermore, the constitutive equation of the Cu–Al2O3/20W composite is established, and the activation energy is 155.069 kJ mol−1.

Deformation Behavior and Dynamic Recrystallization of Hot Deformed GH625 Superalloy

2010 ◽  
Vol 146-147 ◽  
pp. 798-804
Author(s):  
Qing Miao Guo ◽  
De Fu Li ◽  
Sheng Li Guo
Keyword(s):  
Dynamic Recrystallization ◽  
Deformation Temperature ◽  
Volume Fraction ◽  
Optical Microscope ◽  
Strain Rates ◽  
Compression Tests ◽  
Continuous Dynamic Recrystallization ◽  
Transmission Electron ◽  
Lower Strain ◽  
Continuous Dynamic

Microstructure evolution during dynamic recrystallization (DRX) of hot deformed GH625 superalloy was investigated by optical microscope (OP) and transmission electron microscope (TEM). Hot compression tests were conducted using Gleeble-1500 simulator. It was found that the nucleation mechanism of DRX for the alloy deformed at 1150°C is composed of discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) in the vicinity of the serrated grain boundaries. With the increasing strain, the fraction of the DRX grains increases, while the size of the DRX grains almost remains in the same range. As the deformation temperature increasing, the size and fraction of the DRX grains increase, and no precipitation of intergranular carbides are found when the deformation temperature increases to 1150°C. At lower strain rate, the size and volume fraction of DRX grains decrease with the increasing strain rates. However, the size and volume fraction of DRX grains increase at higher strain rates due to the deformation thermal effect.

Growth Kinetics of Interfacial Intermetallic Compound in Al(AA4343)/Steel(SUS316) Clad Strip

2020 ◽  
Vol 993 ◽  
pp. 447-456
Author(s):  
Xiao Jun Zhang ◽  
Kun Yuan Gao ◽  
Xiu Hua Hu ◽  
Yu Sheng Ding ◽  
Guo Zhan Wang ◽  
...  
Keyword(s):  
Growth Kinetics ◽  
Annealing Temperature ◽  
Optical Microscope ◽  
Alloy Layer ◽  
Kinetics Analysis ◽  
Growth Constant ◽  
Transmission Electron ◽  
Dispersive System ◽  
The Relationship ◽  
Kinetics Of

The composition and microstructure of intermetallic compounds (IMC) at the interface of aluminum(AA4343)-stainless steel(SUS316) were studied upon annealing at 550°C for 1h to 20h and at 610°C for 15min to 10h by means of optical microscope(OM) , scanning electron microscope (SEM) with energy dispersive system(EDS) and transmission Electron Microscopy (TEM). The results showed that the IMC was of 4.3μm to 36.1μm thick during heat treatment at 550°C for 1h to 20h, and the IMC contained Al-Fe-Si-Cr-Ni-Mo and Al-Fe-Si -Ni. During annealing at 610°C for 15min to 5h, the thickness of IMC was 31.2 μm to 208 μm, and the IMC were mainly of η-Fe2Al5 and τ10- Al4Fe1.7Si at 550°C for 10h. As the annealing time extended to 10h, natural delamination occurred at the interface between the aluminum alloy layer and IMC layer. The growth kinetics analysis showed that the relationship between the thickness of IMC “X” and time “t” followed the relational equation X=(kt)n. For AA4343(solid) - SUS316(solid), n was 1/2, and the growth constant k = 1.9×10-13m2/s at annealing temperature of 550 °C. When the temperature was 610°C, AA4343 - SUS316 was a liquid-solid contact reaction, n was 1, the growth constant k=1.45×10-8m/s.

scholarly journals Dynamic Recrystallization in a Naturally Deformed Albite

1983 ◽  
Vol 5 (4) ◽  
pp. 219-237 ◽  
Author(s):  
J. D. Fitz Gerald ◽  
M. A. Etheridge ◽  
R. H. Vernon
Keyword(s):  
Dynamic Recrystallization ◽  
Grain Boundaries ◽  
Boundary Migration ◽  
Experimental Studies ◽  
Shear Zones ◽  
Optical Microscope ◽  
Coarse Grained ◽  
Transmission Electron ◽  
Subgrain Growth ◽  
Diffraction Patterns

Coarse-grained, deformed albite occurs in veins within a blueschist from the Cazadero region, California. In some grains, deformation and recrystallization are concentrated in narrow shear zones less than 50 μm wide. We have examined the substructural progression across these zones by transmission electron microscopy (TEM), in an attempt to determine the details of the dynamic recrystallization mechanism. The misorientation across subgrain and recrystallized grain boundaries has been determined by analysis of electron diffraction patterns.Dynamic recrystallization apparently proceeded by the following stages: 1) the formation of a well-ordered substructure from a more tangled, cell-like array, 2) increasing misorientation between subgrains, 3) rapid growth of subgrains at a misorientation between 3° and 5° to produce new “grains” with straighter grain boundaries and lower internal dislocation densities and 4) continued deformation and rotation of the recrystallized grains with local grain-boundary migration to maintain relatively equiaxed shapes. The ultimate recrystallized structure in the narrow deformation zones consists of grains misoriented by between 5° and at least 30°, most of them containing a well-developed substructure.The combination of subgrain growth and rotation explains a number of features common to dynamically recrystallized minerals. The smaller subgrains present prior to growth and also within recrystallized grains form a population distinct from the larger subgrains and recrystallized grains of approximately equal size, which are those observed in an optical microscope. The smaller subgrains are visible only in TEM. Individual recrystallized grains may remain through substantial straining, rotating in response to dislocation and sub-boundary motion within them, thus preserving and even enhancing the crystallographic fabric (texture). The retention of an initial recrystallized grain population throughout significant continuing deformation may explain the absence of strain softening in some recent experimental studies.

Effect of Rare Earth Addition on Dynamic Recrystallization and Precipitation Behavior of a Niobium-Containing Microalloy Steel

2013 ◽  
Vol 762 ◽  
pp. 189-193
Author(s):  
Hai Yan Wang ◽  
Hui Ping Ren ◽  
Hui Yang ◽  
S.D. Wang ◽  
D.X. Li
Keyword(s):  
Rare Earth ◽  
Dynamic Recrystallization ◽  
Dynamic Recovery ◽  
Microalloyed Steel ◽  
Carbon Activity ◽  
Precipitation Behavior ◽  
Rare Earth Addition ◽  
Transmission Electron ◽  
Nb Microalloyed Steel ◽  
Means Of Transmission

Hot compression experiments were carried out on rare earth (RE) added and RE-free Nb-containing steels by using a Gleeble simulator. Stress-strain curves obtained at various temperatures were analyzed to investigate the dynamic recovery and dynamic recrystallization softening behaviours. Morphology, size and number of precipitates in the both steels were examined by means of transmission electron microscopy (TEM). The results showed that, for the experimental Nb-containing steel, the grain size was fined by the RE addtion. In general, dynamic recrystallization cant occur in two steel under 40% deformation rates, and the deformation resistance of RE-containing steel is higher than that of RE-free steel in both the the austenite and ferrite temperatures range.While under the higher deformation rate, the dynamic recovery starting strains of the RE addition steel are higher than that of RE-free steel.It is also shown that the number of precipitate in the RE-containing steel more than that in the RE-free steel, which is due to the RE increasing nucleation rate and promoting Nb carbonitrides precipitation growth in the austenite region. Furthermore, the carbon activity may change by the RE addition, and thereby promote the precipitation strengthening of Nb-microalloyed steel.

20#,60Si2Mn,9Cr18MoV Steel Ferrite Area Dynamic Recovery and Recrystallization Research

2013 ◽  
Vol 690-693 ◽  
pp. 197-201
Author(s):  
Liang Li ◽  
Wen Kai Xiao ◽  
Tao Tao Fan ◽  
Zhou Quan Zhang
Keyword(s):  
Dynamic Recrystallization ◽  
Dynamic Recovery ◽  
Strain Curve ◽  
Carbon Steels ◽  
Test Machine ◽  
Simulation Test ◽  
Microstructure Observation ◽  
Transmission Electron ◽  
Deformation Activation Energy ◽  
Strain Storage

By using the Gleeble - 1500 hot simulation test machine we studied 20#, 60Si2Mn, 9Cr18MoV the three kinds of low, medium and high carbon steels to observe the dynamic recovery and recrystallization of ferrite while in the process of thermoplastic deformation. We calculated the hot deformation activation energy of each kind of steel by combining the stress-strain curve we got in the experiment and the theoretical model of Z parameter. It turns out Q9Cr18MoV<Q20#<Q60Si2Mn. In the meanwhile, microstructure observation through transmission electron microscope shows that the dynamic recrystallization of ferrite is more likely to happen in 9Cr18MoV steel than in 20# steel and in 60Si2Mn steel. These results indicate that the dynamic recrystallization of ferrite is not only determined by stacking fault energy but also closely related with the strain storage energy release degree.

Study on Thermal Deformation and Recrystallization Behavior of Cu-P Weathering Steel

2011 ◽  
Vol 284-286 ◽  
pp. 1228-1231
Author(s):  
Xin Zhang ◽  
Yi Xiong ◽  
Rong Hui He ◽  
Zhi Qiang Li ◽  
Ya Wei Lin
Keyword(s):  
Activation Energy ◽  
Dynamic Recrystallization ◽  
Deformation Process ◽  
Thermal Deformation ◽  
Weathering Steel ◽  
Strain Rates ◽  
Recrystallization Behavior ◽  
Recrystallization Diagram ◽  
Deformation Activation Energy ◽  
Deformation Equation

Under different deformation temperatures and strain rates, the thermal deformation process of Cu-P weathering steel was studied using Gleeble1500D-type thermal simulator. After the high temperature rheopectic curves at different conditions and thermal deformation equation was got, the dynamic recrystallization diagram of the steel was plotted. The results show that the thermal deformation activation energy of the steel is 345kJ/mol, and the dynamic recrystallization diagram of the steel consisits of three parts as completely dynamic recrystallization zone, partially dynamic recrystallization zone and non-dynamic recrystallization zone.

Recrystallization during Beta Working of IMI834

2006 ◽  
Vol 15-17 ◽  
pp. 965-969 ◽  
Author(s):  
Phuong Vo ◽  
Mohammad Jahazi ◽  
Steve Yue
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Titanium Alloy ◽  
Dynamic Recrystallization ◽  
Dynamic Recovery ◽  
Beta Phase ◽  
Heat Treatments ◽  
Strain Rates ◽  
Metadynamic Recrystallization ◽  
Phase Temperature

The microstructure evolution of near-alpha IMI834 titanium alloy during hot working in the beta phase temperature regime has been investigated with regard to the effects of deformation and heat treatments. Typical cogging conditions were simulated through compression testing at temperatures of 1025°C-1100°C, strain rates of 0.01s-1-1s-1, and post- deformation heat treatments up to 4h. An analysis of flow behaviour and as-deformed microstructures revealed mechanisms of dynamic recovery and recrystallization in operation during deformation. However, complete grain refinement was not achieved through dynamic recrystallization and subsequent heat treatment was required for microstructure homogenization through metadynamic recrystallization and grain growth. The mechanisms of dynamic and metadynamic recrystallization are considered through quantitative measures of beta grain size and available literature models.

scholarly journals Hot working behaviour and processing maps of duplex cast steel

2021 ◽  
Vol 112 (7) ◽  
pp. 518-526
Author(s):  
Ignacio Alcelay ◽  
Esteban Peña ◽  
Anas Al Omar
Keyword(s):  
Energy Dissipation ◽  
Dynamic Recrystallization ◽  
Dynamic Recovery ◽  
Cast Steel ◽  
Hot Working ◽  
Strain Rates ◽  
Processing Maps ◽  
Compression Tests ◽  
Temperature Range ◽  
Peak Energy

Abstract In this paper the hot working behaviour of medium carbon duplex cast steel is studied using uniaxial hot compression tests over a temperature range varying from 700 ˚C to 1 000 °C and at different strain rates ranging from 10–4 to 10–1 s–1. A model based on a variant of a dynamic materials model was employed to construct processing maps. These maps delineate the safe and unsafe domains. The safe domains, associated with dynamic recrystallization and dynamic recovery, can be chosen to optimize the hot workability of the studied material. Whereas, the unsafe domain is to be avoided because it is associated with plastic deformation instabilities. The domain associated with dynamic recrystallization is centred at 1000 °C and 10–4 s–1 with a peak energy dissipation efficiency of about 40%, while the domain associated with dynamic recovery is centred at 700 °C and 10–4 s–1 with a peak energy dissipation efficiency of about 27%. The unsafe hot working domain, spread over the entire temperature range and moderate to high strain rates, predicts the appearance of flow instabilities, in the form of shear bands and intergranular cracks. To validate the obtained results, microstructural observations corresponding to different processing conditions are presented.

Hot Deformation Microstructure and Mechanical Properties of Mg-Zn-Nd-Cd-Zr Alloy

2011 ◽  
Vol 311-313 ◽  
pp. 690-696
Author(s):  
Xian Lan Liu ◽  
Chu Ming Liu ◽  
Wen Yu Zhang ◽  
Hui Zhong Li ◽  
Su Min Zeng
Keyword(s):  
Strain Rate ◽  
Elevated Temperatures ◽  
Constant Strain Rate ◽  
Optical Microscope ◽  
Hot Compression ◽  
Strain Rates ◽  
Compression Tests ◽  
Transmission Electron ◽  
Deformation Activation Energy ◽  
Zr Alloy

Hot compression tests of the homogenized Mg-Zn-Nd-Cd-Zr magnesium alloy were performed on Gleeble-1500 at temperatures between 300 °Cand 420 °C and at strain rates ranging from 0.001 to 1 s-1 with maximum strain of 0.8. The microstructure of the experimental alloy in the hot-compression procedure at elevated temperatures was observed by OM (optical microscope) and TEM (transmission electron microscope). The results provide the experimental basis for selecting hot wrought conditions of the alloy. The peak flow stress becomes larger with the increasing strain rate at constant temperature, and gets smaller with the increasing deformation temperature at constant strain rate. The deformation activation energy increases greatly in the range of higher than 420°C, and no more change in the range of 340-380°C. The alloy can be extruded successfully at 360°C with of δb 310 Mpa, δ2 of 290Mpa, and δof 16%。

Effect of Processing Conditions on the Microstructure Development during Constrained Groove Pressing of Aluminium

2014 ◽  
Vol 783-786 ◽  
pp. 331-337 ◽  
Author(s):  
Jozef Zrník ◽  
Libor Kraus ◽  
Miroslav Cieslar ◽  
Peter Sláma
Keyword(s):  
Tensile Strength ◽  
Room Temperature ◽  
Dynamic Recovery ◽  
Processing Conditions ◽  
Structure And Properties ◽  
Transmission Electron ◽  
The Impact ◽  
The Relationship ◽  
Strength And Ductility ◽  
Strain Increase

In this study, the relationship between the structure and properties of commercial purityaluminium (AW-1199) was investigated by applying constrained groove pressing (CGP) method.The refinement of the coarse grain aluminium microstructure to submicrocrystalline size by largeplastic strain at room temperature defined. The impact of various strains upon microstructurechanges is investigated using transmission electron microscopy (TEM) and electron back scatterdiffraction (EBSD). A mixture of subgrains produced by grains subdivision and polygonizedsubgrains formed locally due to dynamic recovery was found in the deformed aluminium. Thetensile properties and resulting hardness are related to microstructural evolution induced by CGP. Asubstantial impact of straining upon the increasing in tensile strength was observed after the firstpass. Further strain increase had an insignificant effect on tensile strength but was accompanied byductility loss. The post deformation annealing effect was then explored with aim to increase theductility. The results indicate that changes in strength and ductility may be related to formation of abimodal structure.

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