Heterogeneous austenite grain growth in ASTM A213 Grade T91 steels: analysis of austenitic grain size distribution using kernel density estimation methodology

This study was presented due to the increasing demand of High Strength Low Alloy (HSLA) steel, such as demand for thinner-walled and large diameter pipes in oil and gas industries. In order to meet the imposed economic restrictions, the high standard of all kinds of steel properties is required and can be achieved by controlling the steel microstructure. The austenite grain size influences the microstructure and properties of steel significantly, in which fine austenite grain size leads to higher strength, better ductility, and higher toughness. Studying the behavior of steel grain growth during the reheating process is still being a fascinating subject. P.R. Rios and D Zollner [1] mentioned that grain growth is the most important unresolved issue that has been a topic of research for many years. In this research, the behavior of austenite grain growth at a high niobium-low carbon (High Nb-low C) and low Nb-high C HSLA steel was evaluated, and the result was compared with other investigation. The results found that the austenite grain growth at high Nb-high C steel was slower than the growth at a low Nb-low C steel. The activation energy of austenite grain growth and both constant A and exponent n ware determined close agreement was obtained between the prediction of the model and the experimental grain size value.

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Local Austenite Grain Size Distribution in Hot Bar Rolling of AISI 4135 Steel

ISIJ International ◽

10.2355/isijinternational.45.706 ◽

2005 ◽

Vol 45 (5) ◽

pp. 706-712 ◽

Cited By ~ 12

Author(s):

Ho-Won LEE ◽

Hyuck-Cheol KWON ◽

Yong-Taek IM ◽

P. D. HODGSON ◽

S. H. ZAHIRI

Keyword(s):

Grain Size ◽

Size Distribution ◽

Grain Size Distribution ◽

Austenite Grain Size ◽

Bar Rolling ◽

Austenite Grain

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Reanalysis of the 3D quasi-stationary grain size distribution based on Hillert's grain growth rate equation

Science in China Series E ◽

10.1007/bf03037688 ◽

2004 ◽

Vol 47 (1) ◽

pp. 112-120

Author(s):

Chao Wang ◽

Guoquan Liu

Keyword(s):

Growth Rate ◽

Grain Size ◽

Size Distribution ◽

Grain Growth ◽

Grain Size Distribution ◽

Rate Equation

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The Correlation Theory of 2D Normal Grain Growth

Materials Science Forum ◽

10.4028/www.scientific.net/msf.467-470.1081 ◽

2004 ◽

Vol 467-470 ◽

pp. 1081-1086 ◽

Cited By ~ 1

Author(s):

M.W. Nordbakke ◽

N. Ryum ◽

Ola Hunderi

Keyword(s):

Grain Size ◽

Size Distribution ◽

Grain Growth ◽

Grain Size Distribution ◽

Computer Simulations ◽

Mean Field Theory ◽

Mean Field ◽

Grain Structures ◽

Spatial Grain ◽

Kinetics Of

Computer simulations of 2D normal grain growth have shown that size correlations between adjacent grains exist in 2D grain structures. These correlations prevail during the coarsening process and influence on the kinetics of the process and on the grain size distribution. Hillert’s analysis starts with the assumption that all grains in the structure have the same environment. Since computer simulations contradict this assumption, the mean-field theory for normal grain growth needs to be modified. A first attempt was made by Hunderi and Ryum, who modified Hillert’s growth law to include the effect of spatial grain size correlations. In the 1D case the distributions derived by means of the modified growth law agreed well with simulation data. However, the distribution derived for 2D grain growth retained unwanted properties of the Hillert distribution. We review some recent progress in developing a mean-field statistical theory. A paradox related to curvilinear polygons is shown to support the expectation that the grain size distribution has a finite cutoff.

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

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.172-174.809 ◽

2011 ◽

Vol 172-174 ◽

pp. 809-814 ◽

Cited By ~ 2

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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