A Study of Abnormal Behavior of Grain Growth in High-Strength Boron-Added Steel

2007 ◽  
Vol 558-559 ◽  
pp. 767-770
Author(s):  
You Hwan Lee ◽  
Sang Yoon Lee ◽  
Duk Lak Lee
Keyword(s):  
Grain Growth ◽  
High Strength ◽  
Production Costs ◽  
Abnormal Behavior ◽  
Manufacturing Processes ◽  
Optimum Amount ◽  
Grain Coarsening ◽  
Production Processes ◽  
Austenite Grain ◽  
Tensile Fatigue

In order to save natural resources and to reduce production costs, many industries have conducted studies on new developed steels and manufacturing processes. For instance, the use of high-strength bolts can decrease the number, size and weight of bolts used in a car, thereby decreasing fuel consumption. For this reason, steel makers are developing boron-added steel for high-strength bolts, which eliminates production processes. However, it has been pointed out that this boron-added steel is sensitive to austenite grain coarsening. The austenite grain coarsening does not occur uniformly, hence it can affect mechanical properties such as tensile, fatigue and so on. Therefore, the aim of this study is to investigate the abnormal behavior of grain growth and to determine the optimum amount of alloying elements in boron-added steel for use in making high-strength bolts.

Austenite Grain Stability of Titanium-Modified Carburizing Steel

2006 ◽  
Vol 118 ◽  
pp. 3-8 ◽  
Author(s):  
Takashi Tanaka ◽  
Takeshi Fujimatsu ◽  
Kazuya Hashimoto ◽  
Kazuhiko Hiraoka
Keyword(s):  
Grain Growth ◽  
Hot Forging ◽  
High Strength ◽  
Cold Forging ◽  
Austenite Grain Size ◽  
Grain Coarsening ◽  
Growth Property ◽  
Austenite Grain ◽  
Automobile Components ◽  
The Cost

It is important to suppress grain coarsening during the carburizing treatment of automobile components such as gears and shafts so that high strength is maintained and heat treatment distortion is minimized. Two manufacturing methods are often used for the cost reduction. One is the increasing carburizing temperature. The other is the adoption of cold forging instead of hot forging. These methods are likely to result in grain coarsening in the case of conventional steels. It is well known that the key factors to control the grain growth are the initial austenite grain size and the volume and mean size of precipitates. In this study, the grain growth property of Ti-modified steel was investigated to confirm the influence of precipitates, and compared with those of Nb-modified and conventional steels. The influence of forging temperature on the grain growth property in a Ti-modified steel was also investigated.

scholarly journals Precipitation Criterion for Inhibiting Austenite Grain Coarsening during Carburization of Al-Containing 20Cr Gear Steels

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 504
Author(s):  
Huasong Liu ◽  
Yannan Dong ◽  
Hongguang Zheng ◽  
Xiangchun Liu ◽  
Peng Lan ◽  
...  
Keyword(s):  
Grain Growth ◽  
Abnormal Grain Growth ◽  
Grain Structure ◽  
Pinning Force ◽  
Grain Coarsening ◽  
Zener Pinning ◽  
Austenite Grain ◽  
Composition Optimization ◽  
Gear Steels ◽  
Grain Growth Behavior

AlN precipitates are frequently adopted to pin the austenite grain boundaries for the high-temperature carburization of special gear steels. For these steels, the grain coarsening criterion in the carburizing process is required when encountering the composition optimization for the crack-sensitive steels. In this work, the quantitative influence of the Al and N content on the grain size after carburization is studied through pseudocarburizing experiments based on 20Cr steel. According to the grain structure feature and the kinetic theory, the abnormal grain growth is demonstrated as the mode of austenite grain coarsening in carburization. The AlN precipitate, which provides the dominant pinning force, is ripened in this process and the particle size can be estimated by the Lifshitz−Slyosov−Wagner theory. Both the mass fraction and the pinning strength of AlN precipitate show significant influence on the grain growth behavior with the critical values indicating the grain coarsening. These criteria correspond to the conditions of abnormal grain growth when bearing the Zener pinning, which has been analyzed by the multiple phase-field simulation. Accordingly, the models to predict the austenite grain coarsening in carburization were constructed. The prediction is validated by the additional experiments, resulting in accuracies of 92% and 75% for the two models, respectively. Finally, one of the models is applied to optimize the Al and N contents of commercial steel.

scholarly journals Characteristics of Precipitates and Austenite Grain Growth in Nb and Ti Bearing High Strength Steels

1981 ◽  
Vol 67 (11) ◽  
pp. 1990-1999 ◽  
Author(s):  
Hiroshi KOBAYASHI ◽  
Yutaka KASAMATU
Keyword(s):  
Grain Growth ◽  
High Strength Steels ◽  
High Strength ◽  
Austenite Grain ◽  
Austenite Grain Growth

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.

Effect of Niobium Additions on Austenite Grain Coarsening Behavior of GCr15 Bearing Steel

2015 ◽  
Vol 817 ◽  
pp. 121-126 ◽  
Author(s):  
Xiang Liu ◽  
Fan Zhao ◽  
Zheng Qiang Dong ◽  
Chao Lei Zhang ◽  
Yu Shan Kou ◽  
...  
Keyword(s):  
Grain Growth ◽  
Bearing Steel ◽  
Grain Coarsening ◽  
Soaking Time ◽  
Experimental Steel ◽  
Austenite Grain ◽  
Gcr15 Bearing Steel ◽  
Coarsening Behavior ◽  
Growth Equations ◽  
Soaking Temperature

The effect of 0.018% niobium additions on austenite grain coarsening behavior of GCr15 bearing steel was studied. Results indicate that the coarsening temperatures of No.1 and the No.2 experimental steel were 950°C and 1100°C. The austenite grain coarsening temperature was increased by 150°C by the addition of 0.018% Nb in bearing steel. The grain growth equations of two experimental steels at different soaking temperatures from 850°C to 1250°C with the soaking time of 30 min are as follows: the equation of No.1 steel is D1=1.85×105·exp (-6.57×104/RT); the equations of No.2 steel below and above 1100°C is D2=5.08×102·exp (-2.49×104/RT) and D2=1.06×108·exp (-1.31×105/RT), respectively. The grain growth equations of two experimental steels at different soaking time from 15 to 120 min with the soaking temperature of 840°C are as follows: the equation of No.1 steel is D1=4.83×10-2·t0.72 while that of No.2 steel is D2=1.25·t0.18.

Development of Anti-Coarsening Steel for Carburizing

2007 ◽  
Vol 539-543 ◽  
pp. 4855-4860 ◽  
Author(s):  
M. Kubota ◽  
T. Ochi
Keyword(s):  
Grain Growth ◽  
Volume Fraction ◽  
Manufacturing Processes ◽  
Negative Effects ◽  
New Techniques ◽  
Grain Coarsening ◽  
Coarsening Behavior ◽  
Coarse Grains ◽  
Austenite Grains ◽  
Austenite Grain Growth

There is a glaring need for omitting intermediate heat treatments in the manufacturing processes of carburized parts and increasing the carburizing temperature aimed at cost reduction. It is necessary to develop techniques to inhibit grain-coarsening since some austenite grains tend to grow abnormally during carburizing and coarse grains have negative effects on the properties of parts. Therefore, we developed new techniques to inhibit grain-coarsening by refining precipitates’ size and increasing their volume fraction based on the abnormal grain growth theory by Gladman. In this study, AlN and Nb(CN) were chosen as the precipitate particles for the pinning of austenite grain growth. And we investigated grain-coarsening behavior in several manufacturing processes of parts. As a result, we developed anti-coarsening steels for various manufacturing processes of carburized parts.

scholarly journals Method for Efficient Regeneration of Solvent Mixture: Extractive Heterogeneous-Azeotropic Distillation

2021 ◽  
Vol 15 (1) ◽  
pp. 103-107
Author(s):  
András József Tóth ◽  
Szilvia Schmidt
Keyword(s):  
Azeotropic Distillation ◽  
Solvent Mixture ◽  
Production Costs ◽  
Manufacturing Processes ◽  
Solvent Mixtures ◽  
Methyl Ethyl ◽  
Production Processes ◽  
Efficient Regeneration ◽  
Pharmaceutical Industries ◽  
Process Simulator

Abstract The fine chemical and pharmaceutical industries use large amounts of various organic solvents in their manufacturing processes. By reusing them, production costs can be significantly reduced. If we can regenerate waste solvent mixtures, we have the opportunity to reuse them in the production process or in other production processes. Our study illustrates an efficient regeneration process using the example of a four-component solvent mixture. Calculations were performed in a professional process simulator to demonstrate that the highly non-ideal Water-Ethyl Alcohol-Methyl Ethyl Ketone-Ethyl Acetate solvent mixture can be efficiently decomposed into azeotropic pairs and thus regenerated by the extractive heterogeneous-azeotropic distillation technique.

scholarly journals Control of Upstream Austenite Grain Coarsening during the Thin-Slab Cast Direct-Rolling (TSCDR) Process

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 158 ◽  
Author(s):  
Tihe Zhou ◽  
Ronald O’Malley ◽  
Hatem Zurob ◽  
Mani Subramanian ◽  
Sang-Hyun Cho ◽  
...  
Keyword(s):  
Thermomechanical Processing ◽  
Liquid Core ◽  
High Strength ◽  
Thin Slab ◽  
Delta Ferrite ◽  
Two Phase ◽  
Austenite Grain Size ◽  
Grain Coarsening ◽  
Austenite Grain ◽  
Direct Rolling

Thin-slab cast direct-rolling (TSCDR) has become a major process for flat-rolled production. However, the elimination of slab reheating and limited number of thermomechanical deformation passes leave fewer opportunities for austenite grain refinement, resulting in some large grains persisting in the final microstructure. In order to achieve excellent ductile to brittle transition temperature (DBTT) and drop weight tear test (DWTT) properties in thicker gauge high-strength low-alloy products, it is necessary to control austenite grain coarsening prior to the onset of thermomechanical processing. This contribution proposes a suite of methods to refine the austenite grain from both theoretical and practical perspectives, including: increasing cooling rate during casting, liquid core reduction, increasing austenite nucleation sites during the delta-ferrite to austenite phase transformation, controlling holding furnace temperature and time to avoid austenite coarsening, and producing a new alloy with two-phase pinning to arrest grain coarsening. These methodologies can not only refine austenite grain size in the slab center, but also improve the slab homogeneity.

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