The microstructure change of low-carbon electrical steels by residual aluminum

1989 ◽  
Vol 47 ◽  
pp. 286-287
Author(s):  
C.K. Hou ◽  
C.T. Hu ◽  
Sanboh Lee
Keyword(s):  
Annealing Treatment ◽  
Low Carbon ◽  
Electrical Steels ◽  
Vacuum Degassing ◽  
Spherical Inclusions ◽  
Residual Aluminum ◽  
Average Grain Size ◽  
The Matrix ◽  
Fine Size ◽  
To Come

The fully processed low-carbon electrical steels are generally fabricated through vacuum degassing to reduce the carbon level and to avoid the need for any further decarburization annealing treatment. This investigation was conducted on eighteen heats of such steels with aluminum content ranging from 0.001% to 0.011% which was believed to come from the addition of ferroalloys.The sizes of all the observed grains are less than 24 μm, and gradually decrease as the content of aluminum is increased from 0.001% to 0.007%. For steels with residual aluminum greater than 0. 007%, the average grain size becomes constant and is about 8.8 μm as shown in Fig. 1. When the aluminum is increased, the observed grains are changed from the uniformly coarse and equiaxial shape to the fine size in the region near surfaces and the elongated shape in the central region. SEM and EDAX analysis of large spherical inclusions in the matrix indicate that silicate is the majority compound when the aluminum propotion is less than 0.003%, then the content of aluminum in compound inclusion increases with that in steel.

Surface Nanocrystallization of Low Carbon Steel Induced by Circulation Rolling Plastic Deformation

2005 ◽  
Vol 475-479 ◽  
pp. 133-136 ◽  
Author(s):  
Xin Min Fan ◽  
Bosen Zhou ◽  
Lin Zhu ◽  
Heng Zhi Wang ◽  
Jie Wen Huang
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Surface Layer ◽  
Carbon Steel ◽  
Severe Plastic Deformation ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Surface Nanocrystallization ◽  
Average Grain Size ◽  
The Matrix

In this paper, the circulation rolling plastic deformation(CRPD) surface nanocrystallization technology is proposed based on the idea that the severe plastic deformation can induce grain refinement. The equipment of CRPD is designed and manufactured. A nanocrystallization surface layer was successfully obtained in a column sample of low carbon steel. The average grain size in the top surface layer is about 18 nm, and gradually increases with the distance from the surface. The hardness increases gradually from about 200HV0.1 in the matrix to about 600HV0.1 in the surface layer.

Influence of MnS Particles inside Grains on the Boundary Migration before Secondary Recrystallization of Grain Oriented Electrical Steels

2010 ◽  
Vol 160 ◽  
pp. 247-250 ◽  
Author(s):  
W. Mao ◽  
Y. Li ◽  
W. Guo ◽  
Z. An
Keyword(s):  
Particle Density ◽  
Boundary Migration ◽  
Secondary Recrystallization ◽  
Annealing Treatment ◽  
Second Phase ◽  
Electrical Steels ◽  
Second Phase Particles ◽  
Dislocation Densities ◽  
The Matrix ◽  
Hot Band

The precipitation behaviors of fine MnS and other second phase particles in hot band, decarburized sheet and 875 oC annealed sheet before secondary recrystallization of conventional grain oriented electrical steel were investigated. It is indicated that the small particles as inhibitors would dissolve in the matrix during cold rolling, and precipitate again in following annealing treatment. The particles inside grains would keep retarding the grain boundary migration. It was found that the particle densities in all grains were quite different before initiation of secondary recrystallization and might be grain orientation dependent, in which Goss grains showed higher particle density. It is expected that the grain boundaries would move towards the grains with lower particle density more easily and promote the rapid growth of Goss grains. The reason for difference of particle densities in different grains is quite complicated. The influence of possible different dislocation densities and the different precipitation behaviors of second phase particles are mentioned.

scholarly journals Effect of Vanadium Reinforcement on the Microstructure and Mechanical Properties of Magnesium Matrix Composites

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 806
Author(s):  
Liqing Sun ◽  
Shuai Sun ◽  
Haiping Zhou ◽  
Hongbin Zhang ◽  
Gang Wang ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Milling Process ◽  
Mg Alloy ◽  
Matrix Composites ◽  
Magnesium Matrix Composites ◽  
Pinning Effect ◽  
Average Grain Size ◽  
The Matrix ◽  
Hot Press Sintering

In this work, vanadium particles (VP) were utilized as a novel reinforcement of AZ31 magnesium (Mg) alloy. The nanocrystalline (NC) AZ31–VP composites were prepared via mechanical milling (MM) and vacuum hot-press sintering. During the milling process, the presence of VP contributed to the cold welding and fracture mechanism, resulting in the acceleration of the milling process. Additionally, increasing the VP content accelerated the grain refinement of the matrix during the milling process. After milling for 90 h, the average grain size of AZ31-X wt % Vp (X = 5, 7.5, 10) was refined to only about 23 nm, 19 nm and 16 nm, respectively. In the meantime, VP was refined to sub-micron scale and distributed uniformly in the matrix, exhibiting excellent interfacial bonding with the matrix. After the sintering process, the average grain size of AZ31-X wt % VP (X = 5, 7.5, 10) composites still remained at the NC scale, which was mainly caused by the pinning effect of VP. Besides that, the porosity of the sintered composites was no more than 7.8%, indicating a good densification effect. As a result, there was little difference between the theoretical and real density. Compared to as-cast AZ31 Mg alloy, the microhardness of sintered AZ31-X wt % VP (X = 5, 7.5, 10) composites increased by 65%, 87% and 96%, respectively, owing to the strengthening mechanisms of grain refinement strengthening, Orowan strengthening and load-bearing effects.

Optimization of thermal conductivity in composites loaded with the solid-solid phase-change materials

2018 ◽  
Vol 25 (6) ◽  
pp. 1157-1165
Author(s):  
Taoufik Mnasri ◽  
Adel Abbessi ◽  
Rached Ben Younes ◽  
Atef Mazioud
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Phase Change Materials ◽  
Solid Phase ◽  
Spherical Inclusions ◽  
First Case ◽  
The Matrix ◽  
Composite Conductivity ◽  
First Time

AbstractThis work focuses on identifying the thermal conductivity of composites loaded with phase-change materials (PCMs). Three configurations are studied: (1) the PCMs are divided into identical spherical inclusions arranged in one plane, (2) the PCMs are inserted into the matrix as a plate on the level of the same plane of arrangement, and (3) the PCMs are divided into identical spherical inclusions arranged periodically in the whole matrix. The percentage PCM/matrix is fixed for all cases. A comparison among the various situations is made for the first time, thus providing a new idea on how to insert PCMs into composite matrices. The results show that the composite conductivity is the most important consideration in the first case, precisely when the arrangement plane is parallel with the flux and diagonal to the entry face. In the present work, we are interested in exploring the solid-solid PCMs. The PCM polyurethane and a wood matrix are particularly studied.

Recrystallization in Ultra-Fine Grain Structures of AA3104 Alloy Processed by ECAP and HPT

2012 ◽  
Vol 715-716 ◽  
pp. 346-353
Author(s):  
H. Paul ◽  
T. Baudin ◽  
K. Kudłacz ◽  
A. Morawiec
Keyword(s):  
High Pressure Torsion ◽  
Deformation Mode ◽  
Second Phase ◽  
Orientation Measurement ◽  
Angular Pressing ◽  
Second Phase Particles ◽  
Average Grain Size ◽  
The Matrix ◽  
Electron Microscopes ◽  
Different Strains

The objective of this study was to determine the effect of deformation mode on recrystallization behavior of severely deformed material. Commercial purity AA3104 aluminum alloy was deformed via high pressure torsion and equal channel angular pressing to different strains and then annealed to obtain the state of partial recrystallization. The microstructure and the crystallographic texture were analysed using scanning and transmission electron microscopes equipped with orientation measurement facilities. The nucleation of new grains was observed in bulk recrystallized samples and during in-situ recrystallization in the transmission microscope. Irrespective of the applied deformation mode, a large non-deformable second phase particles strongly influenced strengthening of the matrix through deformation zones around them. It is known that relatively high stored energy stimulates the nucleation of new grains during the recrystalization. In most of the observed cases, the growth of recrystallized grains occurred by the coalescence of neighboring subcells. This process usually led to nearly homogeneous equiaxed grains of similar size. The diameter of grains in the vicinity of large second phase particles was only occasionally significantly larger than the average grain size. Large grains were most often observed in places far from the particles. TEM orientation mapping from highly deformed zones around particles showed that orientations of new grains were not random and only strictly defined groups of orientations were observed.

Computational Fluid Dynamics Study of New Vacuum Degassing Process

2009 ◽  
Vol 4 (3) ◽  
Author(s):  
Manas Kumar Mondal ◽  
Govind Sharan Gupta ◽  
Shin-ya Kitamura ◽  
Nobuhiro Maruoka
Keyword(s):  
Fluid Flow ◽  
Gas Flow ◽  
Low Carbon Steel ◽  
Momentum Balance ◽  
Low Carbon ◽  
Decarburization Rate ◽  
Vacuum Degassing ◽  
Liquid Phases ◽  
New Process ◽  
Flow Phenomena

Recently, the demand of the steel having superior chemical and physical properties has increased for which the content of carbon must be in ultra low range. There are many processes which can produce low carbon steel such as tank degasser and RH (Rheinstahl-Heraeus) processes. It has been claimed that using a new process, called REDA (Revolutionary Degassing Activator), one can achieve the carbon content below 10ppm in less time. REDA process, in terms of installment cost, is in between the tank degasser and RH processes. As such, REDA process has not been studied thoroughly. Fluid flow phenomena affect the decarburization rate the most besides the chemical reaction rate. Therefore, momentum balance equations along with k-? turbulent model have been solved for gas and liquid phases in two-dimension (2D) for REDA process. The fluid flow phenomena have been studied in details for this process by varying gas flow rate, depth of immersed snorkel in the steel, diameter of the snorkel and change in vacuum pressure. It is found that the design of the snorkel affects the melt circulation of the bath significantly.

Preparation and Magnetic Properties of Dense NiCuZn Ferrite by Spark Plasma Sintering

2008 ◽  
Vol 368-372 ◽  
pp. 601-603
Author(s):  
Xi Wei Qi ◽  
Ji Zhou ◽  
Zhen Xing Yue ◽  
Ming Ya Li ◽  
Xiu Mei Han
Keyword(s):  
Spark Plasma Sintering ◽  
Annealing Temperature ◽  
Annealing Treatment ◽  
Impurity Phase ◽  
Uniaxial Pressure ◽  
Plasma Sintering ◽  
Average Grain Size ◽  
Conventional Sintering ◽  
Spark Plasma ◽  
Nicuzn Ferrite

Dense NiCuZn ferrites consisting of fine grains were prepared by spark plasma sintering (SPS) at 750°C for 3 min under a uniaxial pressure of 15 MPa. The powders were densified to >95% of theoretical density by the SPS process, and the average grain size of the prepared NiCuZn ferrite was < 1 /m. The saturation magnetization of prepared specimens (without further annealing treatment) was approximate 50.54 emu/g, which was slightly smaller than that of 52.21 emu/g for specimens prepared by conventional sintering at 980°C for 4 h. Phase identifications indicated that prepared NiCuZn ferrite existed impurity phase (Cu2O), and Cu2O would gradually transform to CuO when annealing temperature increased.

scholarly journals 3D MORPHOLOGICAL ANALYSIS OF COMPOSITE MATERIALS WITH AGGREGATES OF SPHERICAL INCLUSIONS

2011 ◽  
Vol 22 (1) ◽  
pp. 153 ◽  
Author(s):  
Arnaud Delarue ◽  
Dominique Jeulin
Keyword(s):  
Composite Materials ◽  
Volume Fraction ◽  
Empirical Distribution ◽  
Geodesic Distance ◽  
Shortest Paths ◽  
Morphological Properties ◽  
3D Images ◽  
Spherical Inclusions ◽  
New Information ◽  
The Matrix

Composite materials containing aggregates of spherical inclusions are studied from 3D images obtained by X-ray microtomography. Using two point statistics in different directions, and the empirical distribution of orientations of pairs of inclusions, interesting details concerning the anisotropy of the distribution of inclusions are obtained and are related to the method of construction for these materials. Some 3D morphological properties, available on the 3D images, give new information on the shape and the distribution of aggregates: tortuosity of shortest paths in the matrix, local volume fraction, geodesic distance function, local histograms of numbers of objects.

scholarly journals Investigation of Primary Recrystallization and Decarbonization with Different Heating Rates of Intermediate Annealing Using Nb-Containing Grain-Oriented Silicon Steel

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1655
Author(s):  
Xin Tian ◽  
Shuang Kuang ◽  
Jie Li ◽  
Jing Guo ◽  
Yunli Feng
Keyword(s):  
Heating Rate ◽  
Electron Backscatter Diffraction ◽  
Optical Microscope ◽  
Primary Recrystallization ◽  
Silicon Steel ◽  
Intermediate Annealing ◽  
Heating Rates ◽  
Average Grain Size ◽  
The Matrix ◽  
20 Nm

An Nb-containing grain-oriented silicon steel was produced through double-stage cold rolling in order to investigate the effect of the heating rate during intermediate annealing on primary recrystallization and decarburization behavior. The microstructure and texture were observed and analyzed by an optical microscope and an electron backscatter diffraction system. A transmission electron microscope was used to observe the precipitation behavior of inhibitors. The decarburization effect during intermediate annealing was also calculated and discussed. The results show that primary recrystallization takes place after intermediate annealing. As the heating rate increases, the average grain size decreases gradually. The textures of {411}<148> and {111}<112> were found to be the strongest along the thickness direction in all of the annealed specimens and are mainly surrounded by HEGB and HAGB (> 45°). A large number of inhibitors with the size of 14~20 nm precipitate are distributed evenly in the matrix. The above results indicate that the higher heating rate during intermediate annealing contributes to both an excellent microstructure and magnetic properties. From the calculation, as the heating rate increases, decarbonization tends to proceed in the insulation stage, and the total amount of carbonization declines.

Corrosion Behavior of Al-Si-Cr-Cu Bearing Low Carbon Steel in A Cyclic Dry/Wet Laboratory Test

2009 ◽  
Vol 79-82 ◽  
pp. 1017-1020 ◽  
Author(s):  
Hui Shu Zhang ◽  
Dong Ping Zhan ◽  
Song Lian Bai ◽  
Zhou Hua Jiang
Keyword(s):  
Carbon Steel ◽  
Electrochemical Impedance ◽  
Low Carbon Steel ◽  
Optical Microscope ◽  
Low Carbon ◽  
Rust Layer ◽  
Electrochemical Behaviors ◽  
Corrosion Rates ◽  
The Matrix ◽  
Corrosion Behaviors

The corrosion behaviors of Al-Si-Cr-Cu bearing low carbon steel and a reference steel Q235 were tested in a cyclic dry/wet environment containing 0.01mol/L NaHSO3 in laboratory. Rust layers were observed by optical microscope (OM), scanning electron microscopy (SEM) and XRD. The electrochemical behaviors of the steels were studied on the polarization curves and electrochemical impedance spectroscopy (EIS). The results indicate that after 120h corrosion test, the annual corrosion rates of the designed steels reduce 42 % than Q235 at least. The corrosion products are generally iron oxyhydroxides and oxides such as FeOOH, γ-FeOOH, α-FeOOH, γ-Fe2O3, Fe3O4. The α-FeOOH possesses good stabilization mainly exits and can improve the corrosion resistance. There are the enrichments of Cu, Cr, Si and Al in the rust layer close to the matrix, which make the rust layer be more compact and protected. The corrosion currents of the two designed steels are lower than that of Q235, the corrosion potentials are higher than that of Q235 after Tafel fitting. The rust layer impedances of the designed steels are higher than that of Q235.

Sign in / Sign up

Export Citation Format

Share Document