Influence of original structure and heating rate on the initial grain size of austenite in hypoeutectoid steel

1968 ◽  
Vol 9 (7) ◽  
pp. 497-500
Author(s):  
K. Z. Shepelyakovskii ◽  
G. A. Ostrovskii
Keyword(s):  
Grain Size ◽  
Heating Rate ◽  
Original Structure ◽  
Hypoeutectoid Steel

A TEM study of the influence of microstructure on the superplastic behavior of a U-5.8 wt.% Nb alloy

1986 ◽  
Vol 44 ◽  
pp. 568-569
Author(s):  
G. Mackiewicz Ludtka
Keyword(s):  
Grain Size ◽  
Heating Rate ◽  
Phase Field ◽  
Single Phase ◽  
Superplastic Behavior ◽  
Two Phase ◽  
Single Phase Field

Historically, metals exhibit superplasticity only while forming in a two-phase field because a two-phase microstructure helps ensure a fine, stable grain size. In the U-5.8 Nb alloy, superplastici ty exists for up to 2 h in the single phase field (γ1) at 670°C. This is above the equilibrium monotectoid temperature of 647°C. Utilizing dilatometry, the superplastic (SP) U-5.8 Nb alloy requires superheating to 658°C to initiate the α+γ2 → γ1 transformation at a heating rate of 1.5°C/s. Hence, the U-5.8 Nb alloy exhibits an anomolous superplastic behavior.

Sintering Process of Nd:YAG Transparent Ceramic

2013 ◽  
Vol 281 ◽  
pp. 475-479
Author(s):  
Bo Wang ◽  
Quan Xi Cao ◽  
Guang Xu ◽  
Sen Tian
Keyword(s):  
Grain Size ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Crystal Structures ◽  
Heating Rate ◽  
Optical Transmittance ◽  
Sintering Process ◽  
X Ray ◽  
Polycrystalline Ceramics ◽  
Scanning Electron

1.0at% Nd:YAG polycrystalline ceramics were sintered at 1420°C, 1500°C, 1600°C and 1730°C respectively by different heating rate (1°C/min and 5°C/min). The crystal structures were indexed by X-ray diffractometer (XRD). The microstructure and the grain size of the samples were characterized by scanning electron microscope (SEM). The optical transmittance spectra of the samples were measured using V-570 UV spectrophotometer. The sintering process of Nd:YAG ceramics and the effect of heating rate on the microstructure of samples have been investigated.

STRUCTURAL CHARACTERISTICS OF (Ba,Sr)TiO3 THIN FILMS BY RAPID THERMAL ANNEALING

2007 ◽  
Vol 14 (01) ◽  
pp. 141-145
Author(s):  
Q. Y. ZHANG ◽  
S. W. JIANG ◽  
Y. R. LI
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Heating Rate ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Rapid Heating ◽  
Structural Characteristics ◽  
High Heating Rate ◽  
Duration Time ◽  
Temperature Heating

The rapid thermal annealing (RTA) process was adapted to crystallize the amorphous ( Ba,Sr ) TiO 3 thin films prepared on Si (111) substrates by RF magnetic sputtering deposition. The effect of annealing temperature, heating rate and duration time on crystallization was studied through X-ray diffraction and atomic force microscopy. The result shows that the crystallinity and grain size were strongly dependent on the temperature, heating rate, and duration time. Higher heating rate leads to smaller grain size. In high heating rate, the grain size shows different dependence of temperature from that of low heating rate. For a heating rate of 50°C/s, the grain size decreased with temperature increasing below 700°C, while after that temperature, the grain size increased slightly with the temperature increasing. At a certain temperature, the crystallinity and surface roughness improved with increase in annealing time, while grain size changed little. The effect of rapid heating rate on the nucleation and grain growth has been discussed, which contributes to the limited grain size of the annealed ( Ba,Sr ) TiO 3 thin films.

scholarly journals The Effect of Ultra-Fast Heating on the Microstructure, Grain Size and Texture Evolution of a Commercial Low-C, Medium-Mn DP Steel

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 877 ◽  
Author(s):  
Alexandros Banis ◽  
Eliseo Hernandez Duran ◽  
Vitaliy Bliznuk ◽  
Ilchat Sabirov ◽  
Roumen H. Petrov ◽  
...  
Keyword(s):  
Grain Size ◽  
Heating Rate ◽  
Rapid Heating ◽  
Texture Evolution ◽  
Heating Time ◽  
Manganese Steel ◽  
Low Carbon ◽  
Fast Heating ◽  
Suitable Alternative ◽  
Heated Sample

The effect of ultra-fast heating on the microstructures of steel has been thoroughly studied over the last year as it imposes a suitable alternative for the production of ultra high strength steel grades. Rapid reheating followed by quenching leads to fine-grained mixed microstructures. This way the desirable strength/ductility ratio can be achieved while the use of costly alloying elements is significantly reduced. The current work focuses on the effect of ultra-fast heating on commercial dual phase grades for use in the automotive industry. Here, a cold-rolled, low-carbon, medium-manganese steel was treated with a rapid heating rate of 780 °C/s to an intercritical peak temperature (760 °C), followed by subsequent quenching. For comparison, a conventionally heated sample was studied with a heating rate of 10 °C/s. The initial microstructure of both sets of samples consisted of ferrite, pearlite and martensite. It is found that the very short heating time impedes the dissolution of cementite and leads to an interface-controlled α → γ transformation. The undissolved cementite affects the grain size of the parent austenite grains and of the microstructural constituents after quenching. The final microstructure consists of ferrite and martensite in a 4/1 ratio, undissolved cementite and traces of austenite while the presence of bainite is possible. Finally, it is shown that the texture is not strongly affected during ultra-fast heating, and the recovery and recrystallization of ferrite are taking place simultaneously with the α → γ transformation.

Microwave Processing of Ceramics

2006 ◽  
Vol 45 ◽  
pp. 857-862 ◽  
Author(s):  
Isabel K. Lloyd ◽  
Yuval Carmel ◽  
Otto C. Wilson Jr. ◽  
Geng Fu Xu
Keyword(s):  
Thermal Conductivity ◽  
Grain Size ◽  
Heating Rate ◽  
Thermal Gradients ◽  
Heating Rates ◽  
Volumetric Heating ◽  
Wide Range ◽  
Conventional Sintering ◽  
Atmosphere Control ◽  
Very High

Microwave (MW) processing is advantageous for processing ceramics with tailored microstructures. Its combination of volumetric heating, a wide range of controlled heating rates, atmosphere control and the ability to reach very high temperatures allows processing of 'difficult' materials like high thermal conductivity AlN and AlN composites and microstructure control in more readily sintered ceramics such as ZnO. MW sintering promotes development of thermal conductivity in AlN (225 W/mK) and its composites (up to 150W/mK inAlN-TiB2 and up to 129 W/mK in AlN-SiC when solid solution is avoided). In ZnO, heating rate controls sintered grain size. Increasing the heating rate from 5°C/min. to 4900°C decreases grain size from ~10 μm (comparable to conventional sintering of the same powder) to nearly the starting particle size (~ 1μm). Microstructural uniformity increases with sintering rate since ultra-rapid MW sintering minimizes the development of thermal gradients due to heat loss.

Induction Hardening of a 0.40 % C Novel Microalloyed Steel: Effects of Heating Rate on the Prior Austenite Grain Size

2018 ◽  
Vol 941 ◽  
pp. 64-70
Author(s):  
Vahid Javaheri ◽  
Nasseh Khodaei ◽  
Tun Tun Nyo ◽  
David A. Porter
Keyword(s):  
Grain Size ◽  
Heating Rate ◽  
Prior Austenite ◽  
Induction Hardening ◽  
High Wear Resistance ◽  
Heating Rates ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Prior Austenite Grain Size ◽  
Prior Austenite Grain

This work explores the effect of heating rate on the prior austenite grain size and hardness of a thermomechanically processed novel niobium-microalloyed 0.40 % carbon low-alloyed steel intended for use in induction hardened slurry pipelines. The aim was to identify the heating rates that lead to the maximum hardness, for high wear resistance, and minimum prior austenite grain size, for high toughness. For this purpose, a Gleeble 3800 machine has been employed to simulate the induction hardening process and provide dilatometric phase transformation data. The prior austenite grain structure has been reconstructed from the EBSD results using a MatlabR script supplemented with MTEX texture and crystallography analyses. Heating rates ranged from 1 to 50 °C/s and the cooling rate was 50 °C/s. The results show that the prior austenite grain size greatly depended on the heating rate: compared to the lower heating rates, the maximum heating rate of 50 C/s produces remarkably fine prior austenite grains and a fine final martensitic microstructure after quenching. In addition, a relation between the heating rate and the deviation from equilibrium temperature has been established.

Surface Dissolution of Hydroxyapatite Prepared by Microwave Sintering

2007 ◽  
Vol 330-332 ◽  
pp. 227-230
Author(s):  
Dong Seok Seo ◽  
Hwan Kim ◽  
Kyu Hong Hwang ◽  
Jong Kook Lee
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Heating Rate ◽  
Microwave Sintering ◽  
Starting Material ◽  
Dissolution Behavior ◽  
Distilled Water ◽  
Sintering Process ◽  
Conventional Sintering ◽  
Boundary Dissolution

The aim of this study was to prepare dense hydroxyapatite (HA) by microwave sintering and to evaluate the dissolution behavior in distilled water. Commercially-obtained HA powders having Ca/P ratio of 1.67 were used as a starting material. The as-received powder of granular type consists of nano-sized particles. Microwave sintering was operated at 1200°C for 5 min with a heating rate of 50°C/min. Microwave sintering process reduced grain size of HA, compared with the case of conventional sintering. During the immersion in distilled water for 3-14 days, grain boundary dissolution occurred and the dissolution extended into the bulk following this path. As a result, particles were separated from the structure leaving micron-scale defects.

Effect of Gel-Calcination on Piezoelectric Property in (1-x)BiScO3-xPbTiO3 Ferroelectrics

2010 ◽  
Vol 434-435 ◽  
pp. 335-339
Author(s):  
Han Wang ◽  
Xiao Hui Wang ◽  
Shao Peng Zhang ◽  
Long Tu Li ◽  
Zhao Hui Huang
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Piezoelectric Property ◽  
Relative Density ◽  
Heating Rate ◽  
Piezoelectric Coefficient ◽  
Piezoelectric Properties ◽  
Processing Condition ◽  
Powder Particle Size ◽  
Different Temperatures

In this paper, the effect of gel-calcination on piezoelectric property in (1-x) BiScO3-xPbTiO3 with the composition of x=0.635 is investigated. According to previous work, the heating rate of 200°C/h and holding for 210min having been taken as the basic processing condition. The BSPT powders were obtained from the same sol solution but calcined at different temperatures, and then the powders were used to prepare BSPT ceramics. The result shows that for the bulk ceramics with higher relative density ( higher than 95%), with the increasing calcining temperature of the gel (from 420°C to 500°C), the piezoelectric coefficient d33 of ceramic specimens first increases to maximum of 636pC/N at 450°C, then shows a fluctuation. In this work how the powder activity and the grain size affect (which was leaded by powder particle size) piezoelectric properties of BSPT ceramics are discussed.

Non-Isothermal Austenite Grain Growth Kinetics in the HAZ of a Microalloyed X-80 Linepipe Steel

2011 ◽  
Vol 172-174 ◽  
pp. 809-814 ◽  
Author(s):  
Kumkum Banerjee ◽  
Michel Perez ◽  
Matthias Militzer
Keyword(s):  
Grain Size ◽  
Heating Rate ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Electron Microscopic ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Grain Growth Kinetics ◽  
Austenite Grain Growth ◽  
Linepipe Steel

Non-isothermal austenite grain growth kinetics under the influence of several combinations of Nb, Ti and Mo containing complex precipitates has been studied in a microalloyed linepipe steel. The goal of these studies is the development of a grain growth model to predict the austenite grain size in the weld heat affected zone (HAZ). A detailed electron microscopic investigations of the as-received steel proved the presence of Ti-rich, Nb-rich and Mo-rich precipitates. Inter and intragranular precipitates of ~5-150 nm have been observed. The steel has been subjected to austenitizing heat treatments to selected peak temperatures of 950, 1150 and 1350°C at various heating rates of 10, 100 and 1000°C/s. Thermal cycles have been found to have a strong effect on the final austenite grain size. The increase in heating rate from 100 to 1000°C/s has a negligible difference in the austenite grain size irrespective of the austenitizing temperature. However, the increase in grain size has been noticed at 10°C/s heating rate for all the austenitizing temperatures. The austenite grain growth kinetics have been explained taking into account the austenite growth in the presence of precipitates.

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