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.

Deformation Behavior of Polycrystalline Fe-Ga-B Alloy at Elevated Temperature

2011 ◽  
Vol 687 ◽  
pp. 467-473
Author(s):  
Ji Heng Li ◽  
Xue Xu Gao ◽  
Jie Zhu ◽  
Xiaoqian Bao ◽  
Mao Cai Zhang
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Dynamic Recovery ◽  
High Strain ◽  
Strain Rate Range ◽  
Test Machine ◽  
Compression Tests ◽  
Simulation Test ◽  
Deformation Activation Energy

In this work, the hot deformation behavior of Fe83Ga17alloy with 1.0 at.% B addition was investigated by plane strain compression tests on a Gleeble-1500 hot simulation test machine in the deformation temperature range of 350 to 900 °C. The effects of strain rate range 0.1-10 s-1on flow stress and microstructure were also studied. It was indicated that as the temperature increases, significant softening of the material occurred, and significant dynamic recovery at low strain rate (0.1 s-1) and recrystallization at high strain rate (10 s-1) occurred during deformation at 900 °C. The results also suggested that deformation mechanism under low temperature (~500°C) was twinning. The hot deformation activation energy (Q) of the Fe83Ga17with 1.0 at.%B alloy was calculated to be 295.3 kJ/mol.

Formation of (Ferrite+Cementite) Microduplex Structure by Warm Deformation in High Carbon Steels

2007 ◽  
Vol 539-543 ◽  
pp. 155-160 ◽  
Author(s):  
Tadashi Furuhara ◽  
Takuto Yamaguchi ◽  
Shoji Furimoto ◽  
Tadashi Maki
Keyword(s):  
Dynamic Recrystallization ◽  
Critical Strain ◽  
Dynamic Recovery ◽  
Carbon Steels ◽  
Duplex Structure ◽  
High Carbon ◽  
Tempered Martensite ◽  
Warm Deformation ◽  
Microstructure Change ◽  
Microduplex Structure

The microstructure change by warm deformation in high-carbon steels with different initial ferrite (α) + cementite (θ) duplex microstructures has been examined. Three kinds of initial structures, i.e., pearlite, α+spheroidized θ and tempered martensite, were prepared using Fe-0.8C-2Mn and Fe-1.0C-1.4Cr alloys and compressed by 30-75% at 973K at a strain rate of 5x10-4 s-1. Equiaxed fine α grains, approximately 2μm in diameter and mostly bounded by high-angle boundaries, are formed with spheroidized θ by dynamic recrystallization during compression of the pearlite by 75%. When the (α+θ) duplex structure containing spheroidized θ was deformed, the original α grains become elongated and only subgrains are formed within them by dynamic recovery. For the tempered martensite, equiaxed α grains similar to those in the deformed pearlite were obtained after 50% compression. This indicates that the critical strain needed for the completion of dynamic recrystallization of α is smaller for the tempered martensite than for the other structures.

scholarly journals Microstructure Evolution of Allotropic Materials during Thermomechanical Processing

2012 ◽  
Vol 710 ◽  
pp. 93-100 ◽  
Author(s):  
Cecilia Poletti ◽  
Fernando Warchomicka ◽  
Martina Dikovits ◽  
Simon Großeiber
Keyword(s):  
Phase Transformation ◽  
Dynamic Recrystallization ◽  
Constitutive Equations ◽  
Power Dissipation ◽  
Hot Deformation ◽  
Power Efficiency ◽  
Dynamic Recovery ◽  
Carbon Steels ◽  
Processing Maps ◽  
Strain And Strain Rate

The microstructure developed during hot deformation is the result of deformation mechanisms such as dynamic recovery and dynamic recrystallization. Hot deformation can also result in damage and flow localisation, especially in multiphase metal based materials. Several models have been proposed to correlate the parameters of the deformation process (temperature, strain and strain rate) with the flow behaviour such as the processing maps. They were developed based on the dynamic materials model (DMM) and later a modified DMM introduced some changes in the calculation of the processing maps. The correlation of the relevant microstructural changes with thermodynamic parameters are tested and discussed. The data was obtained by using the Gleeble simulator with in situ quenching facilities. Microstructural studies related to the hot deformation of metals were carried out based on alpha-beta and near beta titanium alloys and on low carbon steels. The results are correlated with the efficiency of power dissipation, and the constitutive equations. In diffusion controlled processes such as dynamic recovery, dynamic recrystallization, phase transformation and pore coarsening are related to high power efficiency, and to low n exponent. The efficiency of power dissipation is more sensitive to the deformation parameters than the constitutive equations for materials with phase transformation.

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.

Flow Stress Behavior of Al-3.5Cu-1.0Li-0.4Mg-0.6Zn-0.3Ag Alloy under Hot Tension

2020 ◽  
Vol 1003 ◽  
pp. 20-25
Author(s):  
Dai Hong Xiao ◽  
Ning Liu ◽  
Wen Sheng Liu
Keyword(s):  
Activation Energy ◽  
Dynamic Recovery ◽  
Strain Curve ◽  
Tensile Tests ◽  
Strain Rates ◽  
Stress Strain Curve ◽  
Aluminum Lithium Alloy ◽  
Deformation Activation Energy ◽  
Aluminum Lithium ◽  
Heat Activation

The hot deformation behavior and microstructure evolution of Al-3.5Cu-1.0Li-0.4Mg- 0.6Zn-0.3Ag aluminum lithium alloy were investigated by hot tensile tests on Gleeble-1500 thermal simulator at 480-510 °C and strain rates 0.0001-0.1 s-1. The results show that obvious flow steady-state phenomena occur during hot stretching and the main mechanism changes from dynamic recovery to dynamic recrystallization with the increase of temperature and decrease of strain rate. The constitutive equation was calculated using the true stress-strain curve obtained by the hyperbolic sinusoidal pair of deformation activation energy Q and temperature T proposed by Sellars and Tegart. The deformation heat activation energy is 226.783 KJ/mol.

scholarly journals HOT COMPRESSION DEFORMATION BEHAVIOR AND CONSTITUTIVE ANALYSIS OF EXTRUDED MAGNESIUM-BISMUTH ALLOYS

2021 ◽  
Vol 6 (3) ◽  
pp. 121-130
Author(s):  
Guoyuan XIONG ◽  
Lihua LIU ◽  
Shuping HOU ◽  
Weimin ZHAO ◽  
Hui YU ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Peak Stress ◽  
Test Machine ◽  
Isothermal Compression ◽  
Simulation Test ◽  
Stress Variation ◽  
Softening Mechanism ◽  
Constitutive Analysis ◽  
Higher Temperature

The isothermal compression experiments of Mg-2Bi alloys were carried out under different temperature and strain rate by Gleeble 3500D thermal simulation test machine. The rheological stress variation law of the Mg-2Bi alloy was analysed under 200-350oC and 0.001-1.0 s-1. The results present that the peak stress enhances and the dynamic recrystallization grain size reduces with the decline of deformation temperature and the improvement of strain rate during isothermal compression of the Mg-2Bi alloy. In addition, the activation energy for alloy deformation is 130.03 kJ/mol. The softening mechanism of the Mg-2Bi alloy is mainly twin and dynamic recrystallization under a low temperature (200oC) condition. While at a higher temperature of 350oC, the softening mechanism changes to single dynamic recrystallization.

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.

scholarly journals Hopkinson rod test results and constitutive description of TRIP780 steel resistance spot welding material

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 961-967
Author(s):  
Xiaomin Li ◽  
Jianrong Zhang
Keyword(s):  
Spot Welding ◽  
Steel Strip ◽  
Strain Curve ◽  
Test Machine ◽  
Strain Rates ◽  
Test Results ◽  
Welding Material ◽  
Static Tensile ◽  
Split Hopkinson ◽  
Brittle Fractures

Abstract A quasi-static tensile test was performed on a 1.4 mm-thick TRIP780 steel strip with welding points. An MTS810 material test machine was used in the test, and a Split Hopkinson tension bar device was used in performing impact stretch loading at different strain rates. The dynamic tensile stress–strain curve of the spot welding material with different strain rates was obtained through the finely designed Hopkinson rod test, and the strain rate dependence of a TRIP780 steel spot welding material was discussed. According to the dynamic constitutive equation of the TRIP780 steel spot welding material, the test results were numerically simulated, the constitutive description and test curves were compared, and the simulation results and test results were discussed and analyzed. The fractures of the test recovery specimen were scanned with the scanning electron microscope, and the fracture mechanism of the TRIP780 steel spot welding material was explored by observing the fractures. The surfaces of the fractures surface showed obvious cleavage river patterns, and the evolution process of microcracks was determined and used in characterizing brittle fractures in specimen spot welding sample subjected to dynamic stretch loading.

Mechanical Properties of Hypereutectoid Steel with Microduplex (α+θ) Structure Formed by Hot Deformation of Undercooled Austenite

2010 ◽  
Vol 654-656 ◽  
pp. 246-249
Author(s):  
Long Fei Li ◽  
Wei Chen ◽  
Wang Yue Yang ◽  
Zu Qing Sun
Keyword(s):  
Mechanical Properties ◽  
Hot Deformation ◽  
Ferrite Matrix ◽  
Subsequent Annealing ◽  
Test Machine ◽  
Compression Tests ◽  
Simulation Test ◽  
Hypereutectoid Steel ◽  
Lamellar Pearlite ◽  
Undercooled Austenite

Microstructure evolution and mechanical properties of hypereutectoid steel with the microduplex (α+θ) structures formed by hot deformation of undercooled austenite were investigated by hot uniaxial compression tests in a Gleeble-1500 simulation test machine, and the effects of subsequent annealing and the addition of Al were analyzed. The results indicated that at the beginning of hot deformation of undercooled austenite the formation of proeutectoid cementite was retrained and only lamellar pearlite was produced. With further strain, dynamic spheroidization of pearlite took place, leading to the formation of microduplex (α+θ) structure consisting of ultrafine ferrite matrix and dispersed cementite particles. In comparison with the normal microstructure consisting of lamellar pearlite and proeutectoid cementite, the microduplex (α+θ) structure presented higher strengths with similar ductility. Subsequent annealing could make the microduplex (α+θ) structure more uniform, which demonstrated better balance between strength and ductility. The addition of Al is disadvantageous to the formation of microduplex (α+θ) structure, but can result in the further refinement. With the addition of Al, the strength of microduplex (α+θ) structure was improved and the ductility was not deteriorated markedly.

Dynamic Recrystallization in Al-Li Based Alloy during Equal Channel Angular Extrusion

2012 ◽  
Vol 715-716 ◽  
pp. 286-291
Author(s):  
Sivaswamy Giribaskar ◽  
Gouthama ◽  
Rajesh Prasad
Keyword(s):  
Dynamic Recrystallization ◽  
Equal Channel Angular Extrusion ◽  
Effective Strain ◽  
Dimensional Change ◽  
Second Phase ◽  
Fine Grained ◽  
Microstructure Observation ◽  
Deformable Particles ◽  
Second Phase Particles ◽  
Angular Extrusion

Development of bulk ultra-fine grained (UFG) materials by severe plastic deformation to attain improved mechanical properties is becoming more attractive and extensively studied nowadays. Equal channel angular extrusion (ECAE) is one of technique used effectively for obtaining bulk UFG materials. Novelty of this technique is one can build up significant amount of plastic strain by increasing the number of passes without much dimensional change. In present investigation dynamic recrystallization at deformation zones around the non-shearable second phase particles in Al-Li based alloy processed by ECAE is reported. Transmission electron microscopy technique involving imaging the regions of such deformation zones with different specimen tilt conditions is used. It is shown that the dynamic recrystallisation occurring in the proximities of second phase particles during the deformation at room temperature, leads to very fine grained microstructure. Observation of multiple active nucleation sites around even sub-micrometer sized non-deformable particles in the as-processed material indicates that the system exhibits efficiency >1 based on the concept of particle stimulated nucleation (PSN). Crystallites of ultra-fine/nanocrystalline size ranges are formed in the deformation zones around the non-deformable particles during deformation itself. Effect of short term post deformation annealing to understand the recovery and recrystallization was undertaken. Based on these results effect of optimal post deformation heat treatment conditions on the thermal stability of the microstructures is emphasized. It is suggested that with significant fraction of non-shearable particles it might be possible to get grain size in the nanocrystalline or ultra-fine range with relatively low effective strain levels using ECAE.

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