Microstructural Observation of Ni-WC Surface Alloyed Carbon Steel

2011 ◽  
Vol 335-336 ◽  
pp. 58-62
Author(s):  
Chang Qing Guo ◽  
Qi Huan Wang
Keyword(s):  
Transitional Zone ◽  
Optical Microscope ◽  
Carbide Precipitation ◽  
Carbon Steels ◽  
Expanded Polystyrene ◽  
Polystyrene Spheres ◽  
Transitional Layer ◽  
The Matrix ◽  
Fine Pearlite ◽  
Carbide Particles

EPS (expanded polystyrene spheres) templates with thickness of a 10 mm coating on a surface that is mainly consisted of Ni-WC particles, are prepared. Carbon steels containing 0.45C%wt are then cast in the templates using V-EPC process (vacuum expandable pattern casting), forming the surface alloyed steels. The microstructures are observed and analyzed using optical microscope, SEM and EDS. Macrostructural observation showed that the surface alloyed zone is dense and there is no obvious defects, such as gas bubbles, occluded gas holes and delimitation. Microstructural investigations indicate that the samples from top to bottom are obviously consisted of three different zones, i.e., the top alloyed zone, the interim transitional zone and the bottom matrix zone. Ni-WC particles are totally decomposed during the molten steel infiltration. The microstructures in the surface alloyed zone are consisted of small amounts of fine WC+W2C carbides, large amounts of M3C+M7C3 carbides and dendritic matrix. There is a fine pearlite strip at the top of the transitional layer. Small amounts of carbide particles within the matrix grains and net carbide precipitation in the grain boundaries at the transitional zone can be observed.

Microstructural Observation of SiC Surface Alloyed Carbon Steel

2011 ◽  
Vol 308-310 ◽  
pp. 2565-2568
Author(s):  
Chang Qing Guo
Keyword(s):  
Casting Process ◽  
Compound Layer ◽  
Optical Microscope ◽  
Carbon Steels ◽  
Expanded Polystyrene ◽  
Surface Compound ◽  
Polystyrene Spheres ◽  
Transitional Layer ◽  
Sic Particles ◽  
Fine Pearlite

EPS (expanded polystyrene spheres) template with a 5 mm coating on a surface that is mainly consisted of SiC particles are prepared. Carbon steels are then poured in the templates using V-EPC (Vacuum Expandable Pattern Casting) process. The microstructures are observed and analyzed using optical microscope, SEM and EDS. Macrostructural observation showed that the surface alloyed zone is dense and there are no obvious defects, such as gas bubbles, occluded gas holes and delimitation. Microstructural investigations indicated that the samples from top to bottom are obviously consisted of three different layers, i.e., the surface compound layer, the interim transitional layer and the bottom matrix layer. SiC particles are totally decomposed during infiltration. The microstructures in the surface compound layer are consisted of a large amount of graphite flakes, carbides, Si rich ferrites and dendritic pearlites. There is a fine pearlite strip at the top of the transitional layer and small amounts of carbide particles within the matrix grains and net carbides at the grain boundaries can be also observed in this layer.

Secondary Hardening during Tempering of Cr-W-Mo-V High Alloy Medium-Upper Carbon Steel and its Hardness Forecast

2011 ◽  
Vol 415-417 ◽  
pp. 813-818 ◽  
Author(s):  
Yong Qing Ma ◽  
Hong Tao Gao ◽  
Yu Fen Liang ◽  
Xiao Jing Zhang
Keyword(s):  
Mass Fraction ◽  
Carbide Precipitation ◽  
Carbon Steels ◽  
Secondary Hardening ◽  
High Alloy ◽  
Quenching Temperature ◽  
Tempering Temperature ◽  
Carbide Phases ◽  
The Matrix ◽  
Exact Temperature

Along with increasing W and Mo contents in Cr-W-Mo-V high alloy medium-upper carbon steels, the maximal hardness of secondary hardening during tempering is increasing gradually and arrives to 66.8HRC, and the congruent quenching temperature and the tempering temperature corresponding to maximal hardness are ascending. The quenching microstructure of experimental steels is matrix and a small quantity of undissolved carbides when the hardness is maximal, wich is corresponding to tempering temperature of remnant austenitic decomposing acutely. The precipitation of M6C and MC carbides was detected, and M7C3 and M3C carbides was detected too. But M23C6 carbide did not appear and M2C carbide was detected undistinguishably. The temperature range of tempering maximal hardness is 500°C-550°C, and an exact temperature is opposite to the mass fraction ratio of equilibrium carbide phases at the temperature. The tempering hardness value can be obtained from HS= a(1+b)/(0.0127a+0.00297), in which a is square root of saturation level of the carbon in the matrix and b is correction factor having something to do with alloy elements of carbide precipitation.

scholarly journals Durability of Modified Expanded Polystyrene Concrete after Dynamic Cyclic Loading

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Wenbo Shi ◽  
Linchang Miao ◽  
Junhui Luo ◽  
Jiaqi Wang ◽  
Yinan Chen
Keyword(s):  
Compressive Strength ◽  
Cyclic Loading ◽  
Volume Ratio ◽  
Inclusion Size ◽  
Expanded Polystyrene ◽  
Practical Significance ◽  
Polystyrene Spheres ◽  
Durability Test ◽  
The Matrix

EPS concrete was produced by mixing the expanded polystyrene spheres (EPS) and polymer emulsion and thickener to the matrix concrete, and this concrete had good vibration energy absorption characteristics. Based on the experimental data obtained on EPS volume ratio of 0%, 20%, 30%, and 40% by replacing matrix or coarse aggregate, the two design styles had nearly the same compressive strength. By applying frequency of 5 Hz, 50000 or 100000 times, 40 KN, 50 KN, and 60 KN cyclic loading, it is shown that the higher the inclusion size was, the lower the compressive strength of the EPS concrete would be; the larger the applying dynamic cyclic load was, the more obvious the compressive strength changing would be. Meanwhile, the strength of EPS concrete had no evident change after durability test. The results of this research had practical significance on using EPS concrete in some long-term cyclic dynamic load engineering.

Analysis and lattice imaging of a transitional event on garnets

1978 ◽  
Vol 36 (1) ◽  
pp. 270-271
Author(s):  
J.Y. Laval
Keyword(s):  
Yttrium Iron Garnet ◽  
Reciprocal Lattice ◽  
Transitional Zone ◽  
Lattice Imaging ◽  
Yttrium Iron ◽  
X Ray ◽  
Ionic Process ◽  
The Matrix ◽  
High Resolution Technique ◽  
Iron Garnet

The exsolution of magnetite from a substituted Yttrium Iron Garnet, containing an iron excess may lead to a transitional event. This event is characterized hy the formation of a transitional zone at the center of which the magnetite nucleates (Fig.1). Since there is a contrast between the matrix and these zones and since selected area diffraction does not show any difference between those zones and the matrix in the reciprocal lattice, it is of interest to analyze the structure of the transitional zones.By using simultaneously different techniques in electron microscopy, (oscillating crystal method microdiffraction and X-ray microanalysis)one may resolve the ionic process corresponding to the transitional event and image this event subsequently by high resolution technique.

Mechanical characterization of LM25 alloy matrix composite reinforced with boron carbide

2021 ◽  
pp. 002199832110055
Author(s):  
Zeeshan Ahmad ◽  
Sabah Khan
Keyword(s):  
Tensile Strength ◽  
Boron Carbide ◽  
Mechanical Characterization ◽  
Stir Casting ◽  
Surface Mapping ◽  
Alloy Matrix ◽  
Casting Technique ◽  
The Matrix ◽  
Carbide Particles

Alumnium alloy LM 25 based composites reinforced with boron carbide at different weight fractions of 4%, 8%, and 12% were fabricated by stir casting technique. The microstructures and morphology of the fabricated composites were studied by scanning electron microscopy and energy dispersive spectroscopy. Elemental mapping of all fabricated composites were done to demonstrate the elements present in the matrix and fabricated composites. The results of microstructural analyses reveal homogenous dispersion of reinforcement particles in the matrix with some little amount of clustering found in composites reinforced with 12% wt. of boron carbide. The mechanical characterization is done for both alloy LM 25 and all fabricated composites based on hardness and tensile strength. The hardness increased from 13.6% to 21.31% and tensile strength 6.4% to 22.8% as reinforcement percentage of boron carbide particles increased from 0% to 12% wt. A fractured surface mapping was also done for all composites.

scholarly journals Study on the Dissolution and Precipitation Behavior of Self-Designed (NbTi)C Nanoparticles Addition in 1045 Steel

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 184
Author(s):  
Hongwei Zhu ◽  
Haonan Li ◽  
Furen Xiao ◽  
Zhixiang Gao
Keyword(s):  
Tensile Strength ◽  
Electron Microscope ◽  
Optical Microscope ◽  
Cast Steels ◽  
Uniform Dispersion ◽  
The Matrix ◽  
Thermo Calc Software ◽  
Particle Strengthening ◽  
1045 Steel ◽  
Addition Amount

Self-designed (NbTi)C nanoparticles were obtained by mechanical alloying, predispersed in Fe powder, and then added to 1045 steel to obtain modified cast steels. The microstructure of cast steels was investigated by an optical microscope, scanning electron microscope, X-ray diffraction, and a transmission electron microscope. The results showed that (NbTi)C particles can be added to steels and occur in the following forms: original ellipsoidal morphology nanoparticles with uniform dispersion in the matrix, cuboidal nanoparticles in the grain, and microparticles in the grain boundary. Calculations by Thermo-Calc software and solubility formula show that cuboidal (NbTi)C nanoparticles were precipitated in the grain, while the (NbTi)C microparticles were formed by eutectic transformation. The results of the tensile strength of steels show that the strength of modified steels increased and then declined with the increase in the addition amount. When the addition amount was 0.16 wt.%, the modified steel obtained the maximum tensile strength of 759.0 MPa, which is an increase of 52% compared with to that with no addition. The hardness of the modified steel increased with the addition of (NbTi)C nanoparticles. The performance increase was mainly related to grain refinement and the particle strengthening of (NbTi)C nanoparticles, and the performance degradation was related to the increase in eutectic (NbTi)C.

The Influence of Oxide Inclusion on the Refinement of Bainite and Toughness in HAZ for Low Carbon Steels

2013 ◽  
Vol 651 ◽  
pp. 163-167
Author(s):  
Shu Rui Li ◽  
Xue Min Wang ◽  
Xin Lai He
Keyword(s):  
Mechanical Properties ◽  
Acicular Ferrite ◽  
Oxide Inclusion ◽  
Optical Microscope ◽  
Carbon Steels ◽  
Low Carbon ◽  
Low Carbon Steels ◽  
The Core ◽  
Ti Oxides ◽  
Bainitic Steels

The influence of Ti oxide on the toughness of heat affected zone for low carbon bainitic steels has been investigated. The optical microscope, SEM and TEM were used to analyze the composition, size and distribution of the inclusions, and the microstructure and mechanical properties after welding thermal simulation were also investigated. The effect of Ti oxide inclusion on the transformation of acicular ferrite has also been studied. The results show that after the melting with Ti dioxide technique the inclusion is complex, in the core is Ti oxides about 1-3 micron and around it is MnS. It has been found the acicular ferrite can nucleate at the inclusions and the Ti oxide inclusion will promote the nucleation of acicular ferrite, and the acicular ferrite will block the growth of bainite. Therefore by introducing the Ti oxide in the steels the microstructure of HAZ could be refined markedly therefore the toughness of HAZ can be improved evidently.

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.

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