Three-Dimensional Observation and Growth Kinetics of Proeutectoid Ferrite Formed at Austenite Grain Boundary in a Low Carbon Microalloyed Steel

2007 ◽  
Vol 539-543 ◽  
pp. 4578-4583 ◽  
Author(s):  
Kai Ming Wu ◽  
A.M. Guo ◽  
Lin Cheng
Keyword(s):  
Grain Boundary ◽  
Growth Kinetics ◽  
Three Dimensional ◽  
Low Carbon ◽  
Austenite Grain ◽  
Ferrite Allotriomorphs ◽  
Proeutectoid Ferrite ◽  
Carbon Microalloyed ◽  
Austenite Grain Boundary ◽  
Kinetics Of

Three-dimensional observations of proeutectoid ferrite formed at grain boundary in an Fe-0.09%C-1.48%Mn vanadium microalloyed alloy was revealed by techniques of serial sectioning along with computer-aided reconstruction. The ferrite allotriomorphs nucleated at grain boundary edges were approximately prolate ellipsoids. Not all the ferrite allotriomorphs formed at grain boundary faces were oblate ellipsoids. The growth kinetics of ferrite allotriomorphs nucleated at grain boundary edges was greater than that of ferrite allotriomorphs nucleated at grain boundary faces.

On the growth kinetics of grain boundary ferrite allotriomorphs

1973 ◽  
Vol 4 (3) ◽  
pp. 783-792 ◽  
Author(s):  
C. Atkinson ◽  
H. B. Aaron ◽  
K. R. Kinsman ◽  
H. I. Aaronson
Keyword(s):  
Grain Boundary ◽  
Growth Kinetics ◽  
Ferrite Allotriomorphs ◽  
Kinetics Of ◽  
Grain Boundary Ferrite

Formation of Martensite Austenite Constituent in Continuously Cooled Nb-Bearing Low Carbon Steels

2010 ◽  
Vol 638-642 ◽  
pp. 3080-3085 ◽  
Author(s):  
Naoki Takayama ◽  
Goro Miyamoto ◽  
Naoya Kamikawa ◽  
Hidenori Nako ◽  
Tadashi Maki ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Volume Fraction ◽  
Bainitic Ferrite ◽  
Carbon Steels ◽  
Low Carbon ◽  
Cooling Rates ◽  
Microstructure Observation ◽  
Austenite Grain ◽  
Austenite Grain Boundary ◽  
Nb Addition

Fe-0.15%C-1.5%Mn-0.2%Si (Nb-free alloy) and Fe-0.15%C-1.5%Mn-0.2%Si-0.03%Nb (Nb-added alloy) were continuously cooled to room temperature at constant cooling rates in the range from 0.1 to 20K/s. At lower cooling rates, such as 0.1K/s, the Nb addition retards the ferrite transformation, resulting in a decrease in the transformation temperature and an increase in the volume fraction of bainite. The fraction of martensite-austenite constituent (MA) increases by the Nb addition and the largest fraction of MA, about 0.5 %, is observed in the Nb-added specimen cooled at 5K/s. In the specimens cooled at 5K/s, relatively coarse bainite without cementite precipitation is formed near the austenite () grain boundary in both alloys. Most of MA is localized between such relatively coarse bainitic ferrite (BF). On the other hand, MA is hardly observed in the bainite formed with cementite precipitation in  grain. Based on microstructure observation of the continuously cooled specimens down to intermediate temperatures followed by quenching, it is concluded that small-sized untransformed  near  grain boundary partly remains as MA whereas relatively larger untransformed  in the  grain decompose into bainite with cementite precipitation.

scholarly journals The Three-Dimensional Morphology and Distribution of CaS Inclusions in Continuous Casting Slab of Ni20Mn6 Steel

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3891
Author(s):  
Jing Chen ◽  
Jing Zhang ◽  
Shaobo Zheng ◽  
Jieyu Zhang
Keyword(s):  
Grain Boundary ◽  
Continuous Casting ◽  
Three Dimensional ◽  
Solidification Structure ◽  
Calcium Sulfide ◽  
Electrolytic Extraction ◽  
X Ray ◽  
Continuous Casting Slab ◽  
Austenite Grain ◽  
Austenite Grain Boundary

Calcium sulfide (CaS) inclusion with large and irregular shape is detrimental to the properties of steel. Understanding the shape and distribution of CaS inclusions in a continuous casting (CC) slab is of significance for improving the rolling properties. In this study, CaS inclusions were extracted from CC slab of Ni20Mn6 steel using the electrolytic extraction and investigated by scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDX). The CaS inclusions morphologies vary with their locations in the CC slab and, thus, are classified into five categories. The thermodynamics calculated results showed that CaS inclusions precipitated at the end of solidification due to the microsegregation of sulfur and calcium in the interdendrite liquid and finally precipitated along the austenite grain boundary. The macrosegregation degree of solutes in different regions is one of the reasons that affect the size of CaS inclusion. The morphologies of CaS inclusion are affected by the solidification structure of slab and austenite grain boundary.

Growth kinetics of grain boundary ferrite allotriomorphs in Fe−C alloys

1977 ◽  
Vol 8 (2) ◽  
pp. 323-333 ◽  
Author(s):  
J. R. Bradley ◽  
J. M. Rigsbee ◽  
H. I. Aaronson
Keyword(s):  
Grain Boundary ◽  
Growth Kinetics ◽  
Ferrite Allotriomorphs ◽  
Kinetics Of ◽  
Grain Boundary Ferrite

scholarly journals Anisotropic Pinning-Effect of Inclusions in Mg-Based Low-Carbon Steel

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2241
Author(s):  
Chi-Kang Lin ◽  
Hsuan-Hao Lai ◽  
Yen-Hao Su ◽  
Guan-Ru Lin ◽  
Weng-Sing Hwang ◽  
...  
Keyword(s):  
Grain Size ◽  
Carbon Steel ◽  
Grain Boundary ◽  
Low Carbon Steel ◽  
In Situ Observation ◽  
Low Carbon ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Austenite Grain Boundary

In this study, the effect of austenite grain size on acicular ferrite (AF) nucleation in low-carbon steel containing 13 ppm Mg is determined. The average austenite grain size was calculated using OM Leica software. Results show that the predicted and experimental values of austenite grain size are extremely close, with a deviation of less than 20 µm. AF formation is difficult to induce by either excessively small and large austenite grain sizes; that is, an optimal austenite grain size is required to promote AF nucleation probability. The austenite grain size of 164 µm revealed the highest capacity to induce AF formation. The effects of the maximum distance of carbon diffusion and austenite grain size on the microstructure of Mg-containing low carbon steel are also discussed. Next, the pinning ability of different inclusion types in low-carbon steel containing 22 Mg is determined. The in situ observation shows that not every inclusion could inhibit austenite grain migration; the inclusion type influences pinning ability. The grain mobility of each inclusion was calculated using in situ micrographs of confocal scanning laser microscopy (CSLM) for micro-analysis. Results show that the austenite grain boundary can strongly be pinned by Mg-based inclusions. MnS inclusions are the least effective in pinning austenite grain boundary migration.

Crystallography of Ferrite Nucleation at Austenite Grain Boundary in a Low Carbon Steel

2010 ◽  
Vol 654-656 ◽  
pp. 7-10 ◽  
Author(s):  
Tadashi Furuhara ◽  
Hayato Saito ◽  
Goro Miyamoto ◽  
Tadashi Maki
Keyword(s):  
Grain Boundary ◽  
Transformation Temperature ◽  
Electron Backscatter Diffraction ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Orientation Relationships ◽  
Austenite Grain ◽  
Austenite Grains ◽  
Austenite Grain Boundary ◽  
Ferrite Nucleation

Orientation relationships of proeutectoid ferrite formed at an austenite grain boundary with respect to adjacent austenite grains were investigated by means of electron backscatter diffraction in an isothermally transformed Fe-1.5Mn-0.2C (mass%) alloy. A grain bounadry ferrite holds nearly the Kurdjumov-Sachs (K-S) orientation relationship with some small misorientation against at least one of the adjacent austenite grains. There is strong variant selection by the austenite grain boundary for ferrite nucleation. At a higher transformation temperature, the fraction of ferrites holding a near K-S relationship with respect to the opposite austenite grain is lower. As the transformation temperature becomes lower, the misorientation from the K-S relationship becomes smaller against the near K-S related austenite grain whereas the misorientation against the irrationally oriented austenite grain becomes larger.

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