Investigation of the Austenite Grain Growth in HY-TUF Steel

2020 ◽  
Vol 299 ◽  
pp. 482-486
Author(s):  
Mikhail V. Maisuradze ◽  
Maksim A. Ryzhkov
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Heating Temperature ◽  
High Strength ◽  
Silicon Steel ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Austenite Grains ◽  
Austenite Grain Growth ◽  
Intensive Growth

The high strength silicon steel HY-TUF, applied for manufacturing of the heavy loaded aerospace and engineering parts, was investigated. The effect of the heating temperature in the range 900...1000 °C on the austenite grain size was studied. The steel under consideration had a significant scatter of the austenite grain size. The most intensive growth of the austenite grains was observed in the temperature range 975...1000 °C.

The Effect of B and Microalloying Elements (V, Ti, Nb) Additions on the Austenite Grain Growth of Low Alloy Steel

2013 ◽  
Vol 197 ◽  
pp. 25-32
Author(s):  
Henryk Adrian ◽  
Marta Pelczar ◽  
Anna Adrian ◽  
Joanna Augustyn-Pieniążek
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Alloy Steel ◽  
Growth Inhibitor ◽  
Vanadium Content ◽  
Low Alloy Steel ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Austenite Grains ◽  
Austenite Grain Growth

The effect of B and microalloying additions of V, V+Ti, V+Nb on austenite grain growth of low alloy steel containing 0.3% C, 1 % Cr and 0.2 % Mo was investigated. As a measure of austenite grain size the mean chord length of austenite grains was assumed. The boron content in investigated steel was in the range of 0 to 0.008 %. The investigations were carried out in austenitising temperature range of 850 to 1100oC. Using the thermodynamic model the contents of undissolved compounds of carbonitride V(C,N) and boron nitride BN were calculated and the effect of undissolved compounds content on austenite grain size was investigated. Obtained results showed, that vanadium content below 0.1 % was ineffective as austenite grain growth inhibitor of boron containing steel and austenite grain size of steel was higher compare to non-alloyed steel. The most effective for decreasing of austenite grains size of boron containing steel was addition of 0.18 % V + 0.03 % Nb

Austenite Grain Evolution Mechanism of High Carbon Rail Based on Thermal Technology

2020 ◽  
Vol 837 ◽  
pp. 74-80
Author(s):  
Jun Yuan ◽  
Zhen Yu Han ◽  
Yong Deng ◽  
Da Wei Yang
Keyword(s):  
Grain Size ◽  
Tensile Strength ◽  
Rail Steel ◽  
Heating Temperature ◽  
Great Influence ◽  
Stable Operation ◽  
High Carbon ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Austenite Grains

In view of the special requirements of rails to ensure the safe and stable operation of Railways in China, the formation characteristics of austenite grains in high carbon rail are revealed through industrial exploration, the process of industrial rail heating and rolling is simulated, innovative experimental research methods such as different heating and heat treatment are carried out on the actual rails in the laboratory. Transfer characteristics of austenite grain size, microstructures and key properties of high carbon rail during the process are also revealed. The results show that the austenite grain size of industrial produced U75V rail is about 9.0 grade. When the holding temperature is increased from 800 C to 1300 C, the austenite grain size of high carbon rail steel decreases, the austenite grain are gradually coarsened, and the tensile strength increases slightly. The tensile strength is affected by the heating temperature. With the increase of heating temperature, the elongation and impact toughness of high carbon rail decrease. The heating temperature of high carbon rail combined with austenite grain size shows that the heating temperature has a great influence on austenite grain size, and has the most obvious influence on the toughness of high carbon rail.

Evaluation of Austenite Grains Growth in High Nb and Low Nb HSLA Steel

2020 ◽  
Vol 1000 ◽  
pp. 404-411
Author(s):  
Eddy S. Siradj
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Oil And Gas ◽  
Hsla Steel ◽  
Large Diameter ◽  
Low Carbon ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Reheating Process ◽  
Austenite Grain Growth

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.

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.

scholarly journals Austenite Grain Growth Kinetics in API X65 and X70 Line-Pipe Steels during Isothermal Heating

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Asiful Hossain Seikh ◽  
Mahmoud S. Soliman ◽  
Abdulhakim AlMajid ◽  
Khaled Alhajeri ◽  
Waleed Alshalfan
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Heating Temperature ◽  
Heating Time ◽  
Austenite Grain Size ◽  
Line Pipe ◽  
Austenite Grain ◽  
Steel Grades ◽  
Grain Growth Kinetics ◽  
Reheating Process

The aim of the present work is to investigate the microstructural behavior of austenite grain size (AGS) during the reheating process of two different API steel grades (X65 and X70). The steel samples were austenitized at 1150°C, 1200°C, and 1250°C for various holding times from 10 to 60 minutes and quenched in ice water. The samples were then annealed at 500°C for 24 hours to reveal the prior AGS using optical microscopy. It was noticed that the AGS in X65 grade is coarser than that of X70 grade. Additionally, the grain size increases with increasing the reheating temperature and time for both steels. The kinetics of grain growth was studied using the equationdn-d0n=Atexp-Q/RT, wheredis the measured grain size,dois the initial grain size,nis the grain size exponent,tis the heating time,Tis the heating temperature,Qis the activation energy,Ris the gas constant, andAis a constant. To characterize the grain growth process the values ofn,Q, andAwere determined. Good agreement is obtained between the prediction of the model and the experimental grain size values.

The Effect of Heating Process on Strength and the Original Austenite Grain Size of Hot Forming Parts

2014 ◽  
Vol 1063 ◽  
pp. 28-31
Author(s):  
Kuan Hui Hu ◽  
Xiang Dong Liu ◽  
Guan Wen Feng ◽  
Rong Dong Han
Keyword(s):  
Grain Size ◽  
Heating Temperature ◽  
Hot Stamping ◽  
Lath Martensite ◽  
Testing Machine ◽  
Heating Process ◽  
Austenite Grain Size ◽  
Heat Temperature ◽  
Austenite Grain ◽  
Austenite Grains

Strength, microstructure and austenitic grain size of a hot formed steel WHT1300HF after simulative hot stamping were studied by using universal testing machine for materials and optical microscopy. The results show that the yield strength of the hot stamping parts presented the tendency of earlier decrease and later increase with the extension of holding time, tensile strength was first reduced and then hold above 1400 MPa. In addition, the microstructure of the hot stamping parts was lath martensite, and martensite lath length and packet width increases with the heating temperature increased from 850 °C to 1050 °C. Especially, the effect of heat temperature on the original austenite grain size was more obvious, such as the austenite grains grew up quickly with the increase of heating temperature, and the original austenite grain diameter was 37.8 μm when the temperature reached 1050 °C.

Austenite Grain Size Model for the Coarse Grain Heat Affected Zone in Line Pipe Steels

2020 ◽  
Author(s):  
Nicolas Romualdi ◽  
Matthias Militzer ◽  
Warren Poole ◽  
Laurie Collins ◽  
Robert Lazor
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Heat Affected Zone ◽  
Arc Welding ◽  
Coarse Grain ◽  
Austenite Grain Size ◽  
Line Pipe ◽  
Austenite Grain ◽  
Girth Welding ◽  
Austenite Grain Growth

Abstract Pipelines are the safest and most cost-effective method of oil and gas transportation to storage and processing facilities. Large diameter welded pipes fabricated by submerged arc welding (SAW) are the preferred product in many cases for pipeline construction. Furthermore, pipelines are constructed by welding segments of pipe, typically by single or dual torch Gas Metal Arc Welding (GMAW). During welding, both during pipe fabrication and girth welding, the Heat Affected Zone (HAZ) experiences rapid thermal cycles with peak temperatures up to the melting temperature of the base metal. Controlling the microstructure evolution in the HAZ during welding of line pipe steels is critical to ensure that these products meet the Charpy impact testing and CTOD requirements imposed by clients and specifications. In particular, the Coarse Grain Heat Affected Zone (CGHAZ) is of concern. Here, austenite grain growth occurs readily due to the combination of high temperature and precipitate dissolution. Controlling the CGHAZ austenite grain size is critical to obtain final microstructures with acceptable impact properties. In this study, austenite grain growth has been measured and modeled for thermal conditions relevant for the CGHAZ in 27 steels, including industrial as well as laboratory steels with systematic variations of alloying element content. Austenite grain size was measured using a Laser Ultrasonics for Metallurgy (LUMet) sensor attached to a Gleeble 3500 Thermomechanical Simulator, which enables high-throughput in-situ monitoring of austenite grain growth. A classical grain growth model has been developed based on a standard test. The grain growth kinetics are described by combining curvature driven grain growth with pinning due to TiN precipitates. A phenomenological relationship has been developed for the grain boundary mobility that decreases with C, Nb and Mo alloying which is consistent with their expected grain boundary segregation. The pinning parameter is rationalized in terms of volume fraction and size of TiN particles. The proposed model has been validated for CGHAZ heat treatment cycles including an industrial welding trial. The results of this study provide a model to predict the austenite grain size in the CGHAZ as a function of steel chemistries and heat treatment paths, i.e. welding parameters. Austenite grain size maps have been constructed as a function of peak local temperature and line pipe steel chemistry. The model can be used both for steel chemistry design and for optimizing welding of steels with known chemical composition to minimize the CGHAZ austenite grain size both during pipe fabrication and girth welding.

Austenite Grain Growth Kinetics during Continuous Heating of a Microalloyed X-80 Linepipe Steel

2012 ◽  
Vol 715-716 ◽  
pp. 292-296
Author(s):  
Kumkum Banerjee ◽  
Michel Perez ◽  
Matthias Militzer
Keyword(s):  
Grain Size ◽  
Heating Rate ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Continuous Heating ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Grain Growth Kinetics ◽  
Austenite Grain Growth ◽  
Linepipe Steel

Non-isothermal austenite grain growth kinetics has been studied in a microalloyed linepipe steel with complex precipitates containing Ti, Nb and/or Mo. The goal of these experimental studies is to provide the basis for the development of a grain growth model to predict the austenite grain size evolution in the weld heat affected zone (HAZ). Detailed electron microscopic investigations of the as received steel proved the presence of Ti-rich, Nb-rich and Mo-rich precipitates. The steel was subjected to austenitizing heat treatments to selected peak temperatures of 950, 1150 and 1350 °C at heating rates of 10, 100 and 1000 °C/s, respectively. Thermal cycles have been found to have a strong effect on the austenite grain size. Austenite grain sizes increase with peak temperature and decreasing heating rate. However, the increase in heating rate from 100 to 1000 °C/s has a negligible effect on the austenite grain size. The observed austenite grain growth kinetics can be explained taking into account the potential dissolution of Nb-rich precipitates.

Effect of Cooling Rate and Nb Composition on Non-Isothermal Austenite Grain Growth Kinetics in Nb-HSLA Steel during Hot Rolling

2012 ◽  
Vol 479-481 ◽  
pp. 414-420 ◽  
Author(s):  
Myrna Ariati ◽  
Azwar Manaf ◽  
Eddy S. Siradj
Keyword(s):  
Grain Size ◽  
Cooling Rate ◽  
Grain Growth ◽  
Hot Rolling ◽  
Isothermal Condition ◽  
Growth Equation ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Hot Rolled ◽  
Austenite Grain Growth

Abstract. The strength of a final product of steel is affected by its final austenite grain size.Almost applied models for grain growth based on Beck and Sellars equation , which has the isothermal condition assumption; whilst most of the materials processing take place under non-isothermal condition. The purpose of this research is to find the effect of Nb and cooling rate to the austenite grain growth model of HSLA-Nb steel to predict the Austenite grain size after hot rolling process in non-isothermal condition .The two composition of 0.019 and 0.056% Nb of HSLA-Nb was hot-rolled about 0.3-0.4 deformation at a temperature of 900-11000 C, followed by cooling rate of 7-11 0 C/s, in a time period of 25-40 second, and quenched by using water jetspray. Austenite final grain size was measured . The work shows that the higher Nb content of steel with higher cooling rate will reduce the final austenite grain size . It was also found that the new non-isothermal austenite grain growth after hot-rolled illustrated as a function of cooling rate,which obtained by modifying the previous established model by a cooling rate parameter 1/Crm, and it was more precision compared to previous grain growth equation.

The Nitrogen Content Effect on Carbonitride Coagulation in 40Cr8 Steel with Micro-Additions V and V + Al

2013 ◽  
Vol 58 (2) ◽  
pp. 607-611 ◽  
Author(s):  
E. Głowacz ◽  
H. Adrian ◽  
W. Osuch
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Grain Size ◽  
Nitrogen Content ◽  
Grain Growth ◽  
Metallographic Analysis ◽  
Coagulation Rate ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Austenite Grain Growth

The work examines the effect of nitrogen and micro-additions V and V+Al on the austenite grain size and the coagulation of carbonitride precipitates in 40Cr8 steel. The analyzed materials underwent heat treatment consisting in holding the material at 1200ºC for 1h, which was next exposed to furnace cooling down to 820ºC and maintained at this temperature for 20hrs, and subsequently quenched in water. With the application of electron microscopy, the microstructure and the formed carbonitride precipitates were examined. The SigmaScanPro software was used to perform the quantitative metallographic analysis of the precipitates. The study demonstrated that increase in the content of nitrogen inhibits the coagulation rate of carbonitrides, whereas aluminium favours the tendency for coagulation and efficiently inhibits the austenite grain growth.

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