scholarly journals Research on the Static Recrystallization and Precipitation Behaviors of a V-N Microalloyed Steel

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Baochun Zhao ◽  
Tan Zhao ◽  
Guiyan Li ◽  
Qiang Lu
Keyword(s):  
Static Recrystallization ◽  
Microalloyed Steel ◽  
Time Interval ◽  
Main Role ◽  
Recrystallization Process ◽  
Compression Tests ◽  
Double Compression ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Temperature Strain

Double compression tests were performed on a Gleeble-3800 thermomechanical simulator to study the softening behaviors of deformed austenite in a V-N microalloyed steel. The static recrystallization volume fractions were calculated by stress offset method, and the kinetic model of static recrystallization was constructed. The effects of temperature, strain, and time interval on the softening behaviors were analyzed, and the interactions between precipitation and recrystallization were discussed. The results show that the softening behaviors of the deformed austenite at lower temperature or higher temperature are markedly different. At the temperature of 850°C or 800°C, pinning effects of the precipitates play the main role, and the recrystallization process is inhibited, which leads to the formation of plateaus in the softening curves. An increase in strain promotes the precipitation and recrystallization processes while reduces the inhibition effect of precipitation on recrystallization as well.

Development of Localized Deformation in AA 2024-O

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
S. Kweon ◽  
A. J. Beaudoin ◽  
P. Kurath ◽  
M. Li
Keyword(s):  
Temperature Gradient ◽  
Work Hardening ◽  
Mechanical Response ◽  
High Strain ◽  
Strain Rates ◽  
Compression Tests ◽  
Localized Deformation ◽  
Aa 2024 ◽  
Higher Temperature ◽  
Lower Temperature

An experimental study is presented to (1) quantify the rate-sensitive mechanical response and (2) examine the localized deformation behavior under an applied temperature gradient in the alloy AA 2024. Isothermal flow stresses are obtained at temperatures from −100°C to 495°C and strain rates from 10−2/s to 10−5/s using routine compression tests and a novel cyclic test, which expedites the characterization. The material displays two distinct kinetic responses with both being amenable to localization phenomena. The lower temperature/high strain rate regime displays a rate-insensitive yield with Stage III/IV work hardening. At higher temperature/low strain rates, a rate-sensitive response with little work hardening is observed. In order to relate the material constitutive behavior to the development of localized deformation, a temperature gradient test is performed wherein temperature differences of approximately 30°C are enforced between the top and bottom surfaces of a cylindrical compression test specimen. Deformation heterogeneity developed in the two distinct regimes of material response is illustrative of warm and hot working conditions typical of industrial processes, such as rolling.

Experimental investigation on static recrystallization behavior of a low carbon Nb–V–Ti microalloyed steel

2021 ◽  
Vol 118 (2) ◽  
pp. 202
Author(s):  
Fei Li ◽  
Liwen Zhang ◽  
Chi Zhang ◽  
Qing Yang ◽  
Chaoqun Li ◽  
...  
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Deformation Temperature ◽  
Static Recrystallization ◽  
Microalloyed Steel ◽  
Pipeline Steel ◽  
Low Carbon ◽  
Compression Tests ◽  
X70 Pipeline Steel ◽  
Deformation Parameters

The static recrystallization (SRX) behavior of a low carbon Nb–V–Ti microalloyed steel X70 was investigated by two-pass hot compression tests. The compression tests were carried out at deformation temperatures of 1000–1150 °C, strain rates of 0.01–5 s−1, pre-strains of 0.1–0.2 and interval times of 1–50 s. The effects of deformation parameters on SRX behavior were analyzed. The experimental results showed that deformation temperature, pre-strain and strain rate had significant influence on SRX fraction, while initial grain size had a smaller impact. The effects of deformation parameters on SRX microstructure were discussed, and the microstructure evolution process was analyzed. Higher deformation temperature, strain rate and pre-strain lead to larger SRX fraction. The kinetics and recrystallized grain size models for SRX of X70 pipeline steel were developed. Comparison between the predicted results and the experimental ones indicated that the established equations could give a reasonable description for SRX behavior of X70 pipeline steel.

scholarly journals Effect of Austenitising and Deformation Temperatures on Dynamic Recrystallisation in Nb-Ti Microalloyed Steel

2013 ◽  
Vol 753 ◽  
pp. 431-434 ◽  
Author(s):  
Andrii G. Kostryzhev ◽  
Abdullah Al Shahrani ◽  
Chen Zhu ◽  
Simon P. Ringer ◽  
Elena V. Pereloma
Keyword(s):  
Microalloyed Steel ◽  
Solute Drag ◽  
Grain Structure ◽  
Temperature Deformation ◽  
Mechanical Processing ◽  
Austenite Grain ◽  
Dynamic Recrystallisation ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Gleeble 3500

An investigation into the influence of the reheat temperature and the austenite deformation temperature on Nb precipitation and recrystallisation kinetics was carried out for a steel containing 0.081C–0.021Ti–0.064Nb (wt. %). Thermo-mechanical processing was carried out using a Gleeble 3500 simulator. The austenite grain structure was correlated to the dispersive properties of Nb atom clustering and precipitation. Irrespective of the reheat temperature, deformation to 0.75 strain at 1075 °C produced a fully recrystallised austenitic microstructure. After deformation at 975 °C, only partial recrystallisation was observed in the samples reheated to the higher temperature, whereas samples reheated to the lower temperature were fully recrystallised. The influence of solute drag and particle pinning effects on the recrystallisation rate is discussed.

Microstructural Evolution of Ultrafine-Grained Steel during Tandem Rolling Process

2010 ◽  
Vol 667-669 ◽  
pp. 415-420
Author(s):  
Xiang Dong Huo ◽  
Xin Ping Mao ◽  
Yi Zhong Chai
Keyword(s):  
Plastic Deformation ◽  
Grain Refinement ◽  
Microalloyed Steel ◽  
Rolling Process ◽  
Strain Accumulation ◽  
Beneficial Effects ◽  
Ultrafine Grained ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Ultrafine Grained Steel

Titanium microalloyed steel whose grain size is around 3μm has been developed by CSP process. Samples after different plastic deformation were obtained by suddenly stopping the six-stand finishing train during tandem rolling. Experimental results and analysis show that plastic deformation during tandem rolling plays a major role for grain refinement. With the successive severe strain, microstructure of the same stock during tandem rolling is further refined because of repeated recrystallization at higher temperature and strain accumulation at lower temperature. Technological features of CSP process, such as large reduction per pass, rapid cooling after rolling and high solidification and of thin slab, are important reasons for obtaining ultafine-grained structure. Besides these, chemical composition of titanium microalloyed steel has beneficial effects on grain refinement.

Study of static recrystallization behavior of austenite in a Ti–V microalloyed steel

2020 ◽  
Vol 10 (7) ◽  
pp. 1047-1056
Author(s):  
Li Wang ◽  
Sufen Xiao ◽  
Zhenghua Tang ◽  
Pingping Qian ◽  
Charles W. Siyasiya
Keyword(s):  
Static Recrystallization ◽  
Microalloyed Steel ◽  
Kinetic Equations ◽  
Processing Parameters ◽  
Compression Tests ◽  
Experimental Conditions ◽  
Kinetics Parameters ◽  
Austenite Grain Size ◽  
Static Softening ◽  
Gleeble 3500

The static recrystallization (SRX) behavior in Ti–V microalloyed steel was studied through two-pass compression tests using a Gleeble-3500 thermo-mechanical simulator. Under the experimental conditions with the deformation temperatures of 950–1050 °C, strain rates of 0.01–1 s–1, pass strains of 0.1–0.2 and inter-pass time of 1–100 s, respectively. The influence of various processing parameters on the static softening were discussed seriously and the results showed that the softening fractions raise quickly with the deformation temperature, the strain rate, the pass strain and the inter-pass time; Oppositely, it is reduced as the initial austenite grain size raises. In addition, the kinetic equations have been adopted and the required parameters have been determined based on the experiments, the calculated results are consistent with the experimental results, indicating the SRX behavior and microstructural evolutions of Ti–V microalloyed steel could be estimated by the determined kinetics parameters.

The effects of experimental conditions on the 950°C kaolinite exotherm in some tropical soil clays

Clay Minerals ◽  
1979 ◽  
Vol 14 (1) ◽  
pp. 21-28 ◽  
Author(s):  
J. C. Hughes
Keyword(s):  
Organic Carbon ◽  
Nitrogen Atmosphere ◽  
Tropical Soil ◽  
Recrystallization Process ◽  
Experimental Conditions ◽  
Exothermic Reactions ◽  
Soil Clays ◽  
Higher Temperature ◽  
Lower Temperature

AbstractSome predominantly kaolinitic tropical soil clays when examined by DTA in a nitrogen atmosphere gave two exothermic reactions (at ∼880°C and ∼950°C) instead of the usual single exotherm. During heating, iron present in the samples is reduced, possibly by organic carbon, and reacts with the metakaolin phase to form hercynite (FeAl2O4). The presence of Fe2+ also causes mullite to form at a lower temperature than normal. These reactions accompany the lower-temperature exotherm. The higher-temperature exotherm is due to formation of γ-alumina. Although this exothermic doublet is an artifact of the experimental conditions, its occurrence may help to elucidate the sequence of reactions involved in the metakaolinite recrystallization process.

scholarly journals Sprouting of Sorghum (Sorghum bicolor [L.] Moench): Effect of Drying Treatment on Protein and Starch Features

Foods ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 407 ◽  
Author(s):  
Mia Marchini ◽  
Alessandra Marti ◽  
Claudia Folli ◽  
Barbara Prandi ◽  
Tommaso Ganino ◽  
...  
Keyword(s):  
Food Production ◽  
Cost Effective ◽  
High Exposure ◽  
Effective Technology ◽  
Drying Treatment ◽  
Higher Temperature ◽  
Lower Temperature ◽  
The One ◽  
Drying Conditions ◽  
Sorghum Bicolor L

The nutritional and physicochemical properties of sorghum proteins and starch make the use of this cereal for food production challenging. Sprouting is a cost-effective technology to improve the nutritional and functional profile of grains. Two drying treatments were used after sorghum sprouting to investigate whether the drying phase could improve the protein and starch functionalities. Results showed that the drying treatment at lower temperature/longer time (40 °C for 12 h) extended the enzymatic activity that started during sprouting compared to the one performed at higher temperature/shorter time (50 °C for 6 h). An increased protein hydrolysis and water- and oil-holding capacity were found in the flour obtained by the former treatment. Higher protein matrix hydrolysis caused high exposure of starch to enzymes, thus increasing its digestibility, while worsening the technological functionality. Overall, modulating drying conditions could represent a further way, in addition to sprouting, to improve sorghum flour’s nutritional profile.

MICROSTRUCTURAL EVOLUTION OF Al-Cu-Mg-Ag ALLOY WITH TRACE Zr ADDITION DURING TWO-STEP HOMOGENIZATION

2009 ◽  
Vol 23 (06n07) ◽  
pp. 855-862 ◽  
Author(s):  
FEIYUE MA ◽  
ZHIYI LIU
Keyword(s):  
Melting Point ◽  
Grain Boundaries ◽  
Microstructural Evolution ◽  
Cast Alloy ◽  
Scanning Calorimetry ◽  
Zr Addition ◽  
Homogenization Time ◽  
The Matrix ◽  
Higher Temperature ◽  
Lower Temperature

The microstructural evolution in an Al - Cu - Mg - Ag alloy with trace Zr addition during homogenization treatment was characterized by Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray Spectroscopy (EDS). It was shown that the low-melting-point phase segregating toward grain boundaries is Al 2 Cu , with a melting point of 523.52°C. A two-step homogenization process was employed to optimize the microstructure of the as-cast alloy, during which the alloy was first homogenized at a lower temperature, then at a higher temperature. After homogenized at 420°C for 6 h, Al 3 Zr particles were finely formed in the matrix. After that, when the alloy was homogenized at an elevated temperature for a longer time, i.e., 515°C for 24 h, most of the precipates at the grain boundaries were removed. Furthermore, the dispersive Al 3 Zr precipitates were retained, without coarsening greatly in the final homogenization step. A kinetics model is employed to predict the optimal homogenization time at a given temperature theoretically, and it confirms the result in present study, which is 420°C/6h+515°C/24h.

Effects of Sr Addition on Mechanical Properties and Microstructure of Mg-6Al Magnesium Alloy

2011 ◽  
Vol 686 ◽  
pp. 120-124
Author(s):  
Jin Ping Fan ◽  
She Bin Wang ◽  
Bing She Xu
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Magnesium Alloy ◽  
Strengthening Mechanism ◽  
Microstructure And Mechanical Properties ◽  
Higher Temperature ◽  
Lower Temperature

The effects of Sr addition on the mechanical properties and microstructure of Mg-6Al mag- nesium alloy both at 25 °C and at 175 °C were investigated by means of OM, SEM and EDS and XRD. Upon the Sr addition of 2%, the tensile strength was increased by 7.2% to 184.4MPa at 25 °C, while it was increased by 30% to 155.4MPa at 175 °C. The strengthening mechanism of Mg-6Al-xSr at lower temperature (25 °C) was different from that at higher temperature (175°C). The results show that the addition of strontium effectively improved the microstructure and mechanical properties of magnesium alloy.

The Effect of Uniaxial Cyclic Deformation on the Evolution of Phase Transformation Fronts in Pseudoelastic NiTi Wire

2001 ◽  
Author(s):  
Mark A. Iadicola ◽  
John A. Shaw
Keyword(s):  
Mechanical Response ◽  
Infrared Imaging ◽  
Partial Transformation ◽  
Niti Wire ◽  
Full Field ◽  
Temperature Experiment ◽  
Background Temperature ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Niti Wires

Abstract Experiments are presented of the response of pseudoelastic NiTi wires subjected to displacement controlled cycles. A custom built thermo-mechanical testing apparatus is used to control the background temperature field of the wire specimen while allowing the evolution of transformation fronts to be tracked by full field infrared imaging. Two experiments under similar end-displacement histories, but at temperatures ≈8°C apart, are shown to give remarkably different cyclic responses. The mechanical response for the lower temperature experiment continued to soften but retained its shape through 43 partial transformation cycles, and the pattern of transformation fronts seemed to reach a steady state. The response for the higher temperature experiment showed a change in shape of the mechanical response and distinct changes in transformation front patterns over 31 partial transformation cycles.

Sign in / Sign up

Export Citation Format

Share Document