Precipitation Behavior of the Second Phase Particles in Grain Oriented Silicon Steel Slabs under Different Reheating Conditions

2014 ◽  
Vol 906 ◽  
pp. 268-274 ◽  
Author(s):  
Xian Hong Chen ◽  
Chen Yi Zhu ◽  
Li Deng ◽  
Guang Qiang Li
Keyword(s):  
Grain Boundary ◽  
Volume Density ◽  
Silicon Steel ◽  
Second Phase ◽  
Precipitation Behavior ◽  
Soaking Time ◽  
Second Phase Particles ◽  
Steel Slabs ◽  
The Common ◽  
Average Size

The grain oriented silicon steel slabs were reheated at 1323K~1623K with different soaking time in this study. The precipitation behavior of the second phase particles in the steel slabs was investigated by using SEM/EDS combined with other analytic tools. The results show that the main precipitations in samples are MnS and AlN bearing a little of CuxS, and they frequently aggregate with each other by two or three types of precipitations. The quantities of the above three types of precipitations are up to 90% in each sample. These complex precipitations change into AlN bearing a little of CuxS or single AlN after being reheated. The shapes of MnS or AlN havent the common spherical or quadrilateral characteristic outline. There are a few of spherical or irregular shape inclusions such as SiO2, Al2O3, TiO2, CaO, CaS and their complex in the samples. Part of MnS or AlN can also grow around with these particles and then dissolves after being reheated. The sizes of the particles are main in the range of 0.05~0.2μm. There are no inclusions larger than 5.0μm in size observed in the fields of view. The volume density of the precipitations 0.05~0.2μm in size extracted from the quenched samples at 1523K using non aqueous solution electroextraction are 4.04×104/mm3, 4.73×104/mm3, 3.70×104/mm3, 3.33×104/mm3, 3.10×104/mm3and 1.56×104/mm3as the corresponding reheating time is 10min, 30min, 60min, 90min, 120min and 240min at 1523K respectively. The average size of them is 0.108μm. It is more precise to statistics the volume density of the particles in the steel by electrolysis extracting method than that of using metallogrphical analysis. No obvious microstructure variation was observed in the quenched samples after annealing different time. When the reheating temperature reaches 1523K and 1623 K, the grain size grows more easily and the grain boundary gets smoothly. The grain boundary of the samples becomes clear with the increase of the annealing temperature during the same annealing time. The reheating temperature in the present slab is chosen at 1523K and the reheating time is kept for 120 min, which will insure the particles in the slab to dissolve more completely and avoid grain growth abnormally at high temperature.

The Study on the Precipitation Behavior of the Second Phase Particles for Fine Grain and High Strength IF Steel

2012 ◽  
Vol 217-219 ◽  
pp. 411-414
Author(s):  
Hong Mei Zhang ◽  
Li Feng Qiao ◽  
Qin Bo Liu
Keyword(s):  
Grain Boundary ◽  
High Strength ◽  
Second Phase ◽  
If Steel ◽  
Precipitation Behavior ◽  
Extraction Replica ◽  
Carbon Extraction Replica ◽  
Fine Grain ◽  
Second Phase Particles ◽  
Precipitate Composition

The new type SFG HSS (super fine grain, high strength steel sheet) has been developed by adding solid-solution strengthening elements to conventional IF steel such as Si, Mn. The precipitation behavior of the second phase particles was observed and studied by a carbon extraction replica technique used transmission electron microscopy (TEM). The shape of the small second particles is similar to spherical and ellipse, the sizes of which are 10~30nm. It is seen that the particles are dispersed on the matrix. The precipitate composition of small particles is Nb (CN) and the precipitate composition of large particles is NbC examined by energy dispersive X-ray (EDX). It is noted that the yield strength is low as well as the tensile strength is high by the PFZ which is free of precipitate called precipitated free zone on the one side of the grain boundary. The results of microstructure shows that the second phase particles pinned on grain boundary not only can inhibit the grain growth, but also the grain can be fined.

Phase-field Model for Diffusional Phase Transformations in Elastically Inhomogeneous Polycrystals

2011 ◽  
Vol 172-174 ◽  
pp. 1084-1089 ◽  
Author(s):  
Tae Wook Heo ◽  
Saswata Bhattacharyya ◽  
Long Qing Chen
Keyword(s):  
Grain Boundary ◽  
Phase Field ◽  
Field Model ◽  
Boundary Segregation ◽  
Phase Field Model ◽  
Transformation Process ◽  
Second Phase ◽  
Perturbation Scheme ◽  
Local Pressure ◽  
Second Phase Particles

A phase-field model is described for predicting the diffusional phase transformation process in elastically inhomogeneous polycrystals. The elastic interactions are incorporated by solving the mechanical equilibrium equation using the Fourier-spectral iterative-perturbation scheme taking into account elastic modulus inhomogeneity. A number of examples are presented, including grain boundary segregation, precipitation of second-phase particles in a polycrystal, and interaction between segregation at a grain boundary and coherent precipitates inside grains. It is shown that the local pressure distribution due to coherent precipitates leads to highly inhomogeneous solute distribution along grain boundaries.

The plasticity and cleavage of polycrystalline beryllium II. The cleavage strength and ductility transition temperature

1980 ◽  
Vol 370 (1740) ◽  
pp. 29-39 ◽  
Keyword(s):  
Transition Temperature ◽  
Flow Stress ◽  
Grain Boundary ◽  
Stress Axis ◽  
Second Phase ◽  
Temperature Dependent ◽  
Second Phase Particles ◽  
Cleavage Strength ◽  
Dependent Flow ◽  
Strength And Ductility

For a grain diameter d, the cleavage strength is proportional to d -1/2 , but intercepts the stress axis. Initiation of cleavage in second phase particles of a size that varies suitably with d could produce this relation. More likely, the cleavage strength is determined by the condition for propagation of a microcrack across a grain boundary. An explanation of the stress intercept is given in terms of the probability that the critical microcrack size is an increasing multiple of d as the grains become finer. Directly measured ductility transition temperatures agree with those deduced from the intersection of a temperature dependent flow stress with a temperature independent cleavage strength.

Combined Effects of Grain Boundary Convection and Migration in Dynamic Phase Transformations

2016 ◽  
Vol 879 ◽  
pp. 72-77
Author(s):  
Frank Montheillet ◽  
David Piot
Keyword(s):  
Grain Boundary ◽  
Phase Transformations ◽  
Large Strain ◽  
Second Phase ◽  
Grain Boundary Mobility ◽  
Dynamic Phase ◽  
Second Phase Particles ◽  
Interphase Boundaries ◽  
And Migration ◽  
Analytical Approaches

During large strain deformation of polycrystals, grain or interphase boundaries are driven by the material flow, which is a convection movement. By contrast, upon static recrystallization or grain growth, their motion takes place with respect to matter, which is referred to as grain boundary or interphase migration. During hot working, where dynamic phase transformations commonly occur, convection and migration operate simultaneously. According to local geometrical (e.g., prescribed velocity field, grain boundary curvature) and physical (e.g., grain boundary mobility, dislocation densities) conditions, they can reinforce or oppose each other, but generally combine in more complex ways. The aim of this work is to analyze such effects on the basis of simple analytical approaches. The results suggest that second phase particles or grains dynamically generated (i.e., during straining) exhibit approximately equiaxed shapes.

Annealing in a Natural Laboratory: an EBSD and Cl Study of Calcite and Quartz Growth from Volumes of Rock Heated by a Nearby Melt Intrusion

2007 ◽  
Vol 550 ◽  
pp. 333-338 ◽  
Author(s):  
Sandra Piazolo ◽  
David J. Prior ◽  
M.D. Holness ◽  
Andreas O. Harstad
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Crystallographic Orientation ◽  
Lattice Distortion ◽  
Temperature History ◽  
Second Phase ◽  
Gradual Change ◽  
Twin Boundaries ◽  
Second Phase Particles ◽  
Crystallographic Orientations

Annealing is an important mechanism of microstructural modification both in rocks and metals. In order to relate directly changes in crystallographic orientation to migrating boundaries the researcher has the option to investigate either samples where the grain boundary motion can be directly tracked or a series of samples exhibiting successively higher degrees of annealing. Here we present results from rock samples collected from two well characterised contact aureoles (a volume of rock heated by the intrusion of a melt in its vicinity): One quartz sample in which patterns revealed by Cathodoluminescence (CL) indicate the movement of grain boundaries and a series of calcite samples of known temperature history. Electron backscatter diffraction (EBSD) analysis is used to link the movement of grain, twin boundaries and substructures with the crystallographic orientation / misorientation of a respective boundary. Results from the quartz bearing rock show: (a) propagation of substructures and twin boundaries in swept areas both parallel and at an angle to the growth direction, (b) development of slightly different crystallographic orientations and new twin boundaries at both the growth interfaces and within the swept area, and (c) a gradual change in crystallographic orientation in the direction of growth. Observations are compatible with a growth mechanism where single atoms are attached and detached both at random and at preferential sites i.e. crystallographically controlled sites or kinks in boundary ledges. Strain fields caused by defects and/or trace element incorporation may facilitate nucleation sites for new crystallographic orientations at distinct growth interfaces but also at continuously migrating boundaries. Calcite samples show with increasing duration and temperature of annealing: (a) systematic decrease of the relative frequency of low angle grain boundaries (gbs), (b) decrease in lattice distortion within grains, (c) development of distinct subgrains with little internal lattice distortion, (d) change in lobateness of gbs and frequency of facet parallel gbs and (e) change in position of second phase particles. These observations point to an increasing influence of grain boundary anisotropy with increasing annealing temperature, while at the same time the influence of second phase particles and subtle driving-force variations decrease. This study illustrates the usefulness of using samples from natural laboratories and combining different analysis techniques in microprocess analysis.

Secondary Recrystallization in Grain-Oriented Silicon Steel

2004 ◽  
Vol 467-470 ◽  
pp. 853-862 ◽  
Author(s):  
Yoshiyuki Ushigami ◽  
Tomoji Kumano ◽  
Tsutomu Haratani ◽  
Shuichi Nakamura ◽  
Shigeto Takebayashi ◽  
...  
Keyword(s):  
Boundary Energy ◽  
Secondary Recrystallization ◽  
Silicon Steel ◽  
Second Phase ◽  
In Situ Observation ◽  
Pinning Force ◽  
Goss Texture ◽  
Second Phase Particles ◽  
The Matrix ◽  
Grain Growth Behavior

Mechanism of Goss secondary recrystallization in grain-oriented silicon steel has been investigated by temperature gradient annealing and by in situ observation utilizing synchrotron x-ray topography. The results support the selective growth theory. Migration of Goss grains is controlled by second phase particles (inhibitor) and sharper Goss grains, which have higher frequency of CSL boundaries to the matrix, start to grow preferentially while the other matrix grains are stagnated by inhibitor. CSL boundaries are supposed to have lower grain boundary energy, thus suffer lower pinning force from the inhibitor and start to migrate at higher inhibition level. Based on this model, we have made a computer simulation and have found that this model successfully depicts the important features of secondary recrystallization; grain growth behavior of secondary grains, secondary grain size and sharpness of Goss texture.

The Effect of Grain-Boundary and Matrix Precipitates on High Temperature Strength in Fe3Al Based Alloys

2011 ◽  
Vol 1295 ◽  
Author(s):  
Ryo Makihara ◽  
Satoru Kobayashi ◽  
Takayuki Takasugi
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Tensile Tests ◽  
High Temperature Strength ◽  
Second Phase ◽  
Proof Stress ◽  
Second Phase Particles ◽  
The Matrix

ABSTRACTThe effect of grain boundary (GB) and matrix precipitates on high temperature strength was investigated in Fe3Al base alloys containing Cr, Mo and C. Tensile tests were conducted at 600°C for three types of microstructures consisting of: (I) film-like κ phase precipitates covering GBs and fine M2C particles in the matrix, (II) only fine M2C particles in the matrix and (III) no second-phase particles in the matrix. It was found that κ films on GBs are more than twice as effective as finely dispersed M2C particles for improving the proof stress.

Study on the Second Phase Particles Precipitation Behavior during Deformation and Cooling of T700

2013 ◽  
Vol 703 ◽  
pp. 102-105
Author(s):  
Zhuo Fei Song ◽  
Xiao Ming Hu ◽  
Yun Li Feng ◽  
Run Ming Feng
Keyword(s):  
Electron Microscopy ◽  
Carbide Precipitation ◽  
Holding Time ◽  
Second Phase ◽  
Precipitation Behavior ◽  
Cooling Process ◽  
Simulation Experiments ◽  
Second Phase Particles ◽  
Quenching Process ◽  
Scanning Electron

In this paper, the precipitation behavior of T700 deformation and cooling process was studied by thermal simulation experiments and scanning electron microscopy. Results show that there are two kinds of carbide precipitates, precipitates needle is epsilon carbide precipitation in bainite, and is precipitated in the quenching process, circular granular precipitates during deformation due to strain induced precipitation. When the holding time is short, amount and size of precipitates are same as precipitation in the deformation. As the holding time longer, the number of precipitates in micro alloyed increase gradually, but very little change in size.

Phase Field Study of Second Phase Particles-Pinning on Strain Induced Grain Boundary Migration

2020 ◽  
Vol 993 ◽  
pp. 967-975
Author(s):  
Kai Li ◽  
Yao Shen ◽  
Da Yong Li ◽  
Ying Hong Peng
Keyword(s):  
Grain Boundary ◽  
Phase Field ◽  
Boundary Migration ◽  
Phase Field Model ◽  
Energy Difference ◽  
Second Phase ◽  
Grain Boundary Migration ◽  
Stored Energy ◽  
Second Phase Particles ◽  
Theoretical Predictions

A phase field model was presented to investigate the effect of particles-pinning on grain boundary migration in materials containing stored energy differences across the grain boundaries. The accuracy of the phase field framework was examined by comparing the simulated results with theoretical predictions. The pinning effects of coherent and non-coherent second phase particles on the boundary migration were studied in triple-grain models. 2D simulations with second phase particles of different sizes or different area fractions were performed. The effect of stored energy difference across the boundary on the particles-pinning was also investigated. The results showed that the pinning effect could be enhanced by the decrement of the particle size and the increment of particle area fraction. Increasing the stored energy difference across the grain boundary induced higher grain boundary migration velocity and weaker particles-pinning.

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