The Aging Behavior for Low Carbon Bainitic Steel Bearing Cu-Nb

2005 ◽  
Vol 475-479 ◽  
pp. 129-132
Author(s):  
Xue Min Wang ◽  
G.F. Zhou ◽  
Cheng Jia Shang ◽  
Shan Wu Yang ◽  
Xin Lai He
Keyword(s):  
Hardness Measurement ◽  
Optical Microscope ◽  
Quantitative Phase Analysis ◽  
Low Carbon ◽  
Precipitation Behavior ◽  
Niobium Carbonitride ◽  
Aging Precipitation ◽  
Analysis Technique ◽  
Carbonitride Precipitation ◽  
Aging Hardening

By the aid of optical microscope, Hardness measurement, SEM, TEM and the chemical quantitative phase analysis technique, the influence of copper, niobium, and chromium on the aging hardness has been investigated. The aging precipitation behavior and the interaction between various precipitates have also been discussed. The results indicate that since there are multi aging-hardening elements in the steel the aging hardening behaviors are complicated. During the aging the ε－copper， and carbides containing iron and chromium will precipitate. Also, new niobium carbonitride precipitation occurs. These precipitation processes cause marked hardening effect and various hardness peaks. The ε－copper can precipitate at dislocation and lath boundaries preferentially. During the aging the bainite lath united and became wider and then gradually vanished.

Aging Precipitation Behavior of Cu-Ag-Cr Alloy

2006 ◽  
Vol 118 ◽  
pp. 41-46 ◽  
Author(s):  
Jing Guo Lei ◽  
Ping Liu ◽  
Bao Hong Tian ◽  
Xiao Zhi ◽  
Xiao Tian Jing
Keyword(s):  
Cold Deformation ◽  
High Strength ◽  
Intermediate Stage ◽  
Precipitation Behavior ◽  
Annealing Temperatures ◽  
Aging Precipitation ◽  
Coarsening Behavior ◽  
High Annealing ◽  
Effects Of Aging ◽  
Aging Hardening

The Cu-Ag-Cr alloy is a kind of aging hardening copper alloy and has excellent combination properties of high strength and good electrical and thermal conductivity. In the present investigation, the aging precipitation behavior of Cu-Ag-Cr alloy is studied, and the effects of aging processes on the microstructure and properties are discussed. Emphasis is on the correlation between the coherency and coarsening behavior of the Cr precipitates. When the alloy aging at low annealing temperatures, the homogeneous dispersed Cr precipitates are observed to be approximately spherical and keep coherent with Cu matrix in the Cu-Ag-Cr alloy, the coherency is lost between at 450°C~520°C, coherency on coarsening process of Cr precipitates at high annealing temperatures, the radium for coherent / semi-coherent transition of the Cr precipitates is determined from TEM micrographs as 15-45nm. Aging in the intermediate stage, coherent and semi-coherent particles can co-exist(15<r<45nm). The precipitation can be accelerated by cold deformation before aging, the 60% deformed Cu-Ag-Cr alloy aging at 480°C for 1h, the hardness and electrical conductivity can respectively reach to 158HV and 85%IACS.

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.

Effect of Warm Deformation on Ferrite Microstructure Evolution in a Ti-Microalloyed Steel

2007 ◽  
Vol 558-559 ◽  
pp. 497-504
Author(s):  
Beitallah Eghbali
Keyword(s):  
Microstructure Evolution ◽  
Microalloyed Steel ◽  
Early Stage ◽  
Microstructural Analysis ◽  
Optical Microscope ◽  
Low Carbon ◽  
High Angle ◽  
Warm Deformation ◽  
Continuous Dynamic Recrystallization ◽  
Continuous Dynamic

Warm deformation is one of the promising hot rolling strategies for producing thin hot rolled steel strips. A better understanding of the microstructure evolution during warm deformation is important for a successful introduction of such processing into the industrial production. In the present research, the effect of deformation strain on the ferrite microstructure development in a low carbon Ti-microalloyed steel was investigated through warm torsion testing. Microstructural analysis with optical microscope and electron back-scattering diffraction was carried out on the warm deformed ferrite microstructures. The results show that at the early stage of deformation an unstable subboundaries network forms and low angle boundaries are introduced in the original grains. Then, with further straining, low angle boundaries transform into high angle boundaries and stable fine equiaxed ferrite grains form. It was considered that dynamic softening and dynamically formation of new fine ferrite grains, with high angle boundaries, were caused by continuous dynamic recrystallization of ferrite.

scholarly journals PELAPISAN PERMUKAAN DALAM NOSEL ROKET RKX100 DENGAN Cr2C3-NiCr HVOF: OPTIMASI KEKUATAN LEKAT MELALUI VARIASI KEKASARAN PERMUKAAN

2010 ◽  
Vol 2 (1) ◽  
Author(s):  
Bondan T.Sofyan ◽  
Yus Prasetyo ◽  
Sayid Ardiansyah ◽  
Yus Prasetyo ◽  
Edy Sofyan
Keyword(s):  
Surface Roughness ◽  
Thermal Spray ◽  
Bonding Strength ◽  
Spray Coating ◽  
Hardness Measurement ◽  
Thermal Spray Coating ◽  
Optical Microscope ◽  
Mechanical Interlocking ◽  
Micro Hardness ◽  
Scanning Electron

Nozzle of RKX100 rocket contributes 30 percent to the total weight of the structure, so that allowing further research on weight reduction. An alternative for this is by substitution of massive graphite, which is currently used as thermal protector in the nozzle, with thin layer of HVOF (High Velocity Oxy-Fuel) thermal spray layer. A series of study on the characteristics of various type of HVOF coating material have been being conducted. This paper presented the investigation on the HVOF Cr2C3-NiCr thermal spray coating, in particular, the optimization of bonding strength by varying surface roughness of substrates. Characterization included bonding strength test, micro hardness measurement and micro structural observation with optical microscope and scanning electron micriscope (SEM). The results showed that grit blasting pressure increass the surface roughness from 4,54 um to 5.72 um at the pressure of 6 bar. Average micro hardness of the coating was 631 VHN 300. Coating applied to the surface with rougness of 5.42 um possessed the highest bonding strength, 44 MPa. Microstructural observation by using optical microscope and scanning electron microscope (SEM) confirmed dense lamellae structure with variable composition. High coating adherence was found to be due to mechanical interlocking.

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.

Microstructure of the Acid Welding Slag

2012 ◽  
Vol 249-250 ◽  
pp. 914-917
Author(s):  
Yuan Bin Zhang ◽  
Kai Zhang
Keyword(s):  
Electron Microscope ◽  
Amorphous Matrix ◽  
Low Carbon Steel ◽  
Optical Microscope ◽  
Crystal Phase ◽  
Low Carbon ◽  
Extrusion Press ◽  
Transmission Electron ◽  
Welding Slag ◽  
Welding Electrode

Several E4303 type welding electrodes with different coating compositions were designed and manufactured using TL-25 welding electrode extrusion press. Welding slags of these electrodes were collected after welding on the low carbon steel, then the microstructure and the phase constitutes of the slags were investigated by optical microscope,scan electron microscope (SEM), electron probe microanalyzer (EPMA), Transmission electron microscope (TEM) and X-ray diffraction (XRD). It was indicated that the slags were mainly composed of amorphous matrix and Fe2MnTi3O10 crystal phase. Fe, Mn and Ti were the main elements to form the crystal phase, while Si, Al and Ca were mostly distributed in the amorphous matrix. The formation of the crystal phase in the slag could be controlled by adjusting the amount and the proportion of Fe, Mn and Ti in the welding rod coating.

Effect of Ti, Al and Mg Addition on the Impact Toughness of Heat Affected Zone in Low Carbon Steel

2009 ◽  
Vol 79-82 ◽  
pp. 143-146
Author(s):  
Jiang Hua Ma ◽  
Dong Ping Zhan ◽  
Zhou Hua Jiang ◽  
Ji Cheng He
Keyword(s):  
Carbon Steel ◽  
Impact Toughness ◽  
Heat Affected Zone ◽  
Low Carbon Steel ◽  
Optical Microscope ◽  
Carbon Steels ◽  
Low Carbon ◽  
Welding Simulation ◽  
Mg Addition ◽  
The Impact

In order to understand the effects of deoxidizer such as aluminium, titanium and magnesium on the impact toughness of heat affected zone (HAZ), three low carbon steels deoxidized by Ti-Al, Mg and Ti-Mg were obtained. After smelting, forging, rolling and welding simulation, the effects of Al, Ti and Mg addition on the impact toughness of HAZ in low carbon steel were studied. The inclusion characteristics (size, morphology and chemistry) of samples before welding and the fracture pattern of the specimens after the Charpy-type test were respectively analyzed using optical microscope and scanning electron microscopy (SEM). The following results were found. The density of inclusion in Ti-Mg deoxidized steel is bigger than Ti-Al deoxidized steel. The average diameter is decreased for the former than the latter. The addition of Ti-Mg can enhance the impact toughness of the HAZ after welding simulation. The maximal value of the impact toughness is 66.5J/cm2. The complex particles of MgO-TiOx-SiO2-MnS are most benefit to enhance impact toughness. The improvement of HAZ is attributable to the role of particle pinning and the formation of intergranular ferrite.

Influence of Li addition on mechanical property and aging precipitation behavior of Al-3.5Cu-1.5Mg alloy

2014 ◽  
Vol 24 (6) ◽  
pp. 1653-1658 ◽  
Author(s):  
Yun-lai DENG ◽  
Jin-long YANG ◽  
Si-yu LI ◽  
Jin ZHANG ◽  
Xin-ming ZHANG
Keyword(s):  
Mechanical Property ◽  
Precipitation Behavior ◽  
Aging Precipitation

scholarly journals PERUBAHAN NILAI KEKERASAN DAN KONDUKTIVITAS LISTRIK ALUMINIUM AKIBAT PROSES EQUAL CHANNEL ANGULAR PRESSING (ECAP)

ROTASI ◽  
2014 ◽  
Vol 16 (4) ◽  
pp. 41
Author(s):  
Rusnaldy Rusnaldy ◽  
Norman Iskandar ◽  
Muhammad Khairul Rais ◽  
Wisnu Tri Erlangga
Keyword(s):  
Electrical Conductivity ◽  
Plastic Deformation ◽  
Equal Channel Angular Pressing ◽  
Hardness Test ◽  
Hardness Measurement ◽  
Optical Microscope ◽  
Pure Aluminium ◽  
Angular Pressing ◽  
Ecap Process ◽  
Number Of Passes

In current study, Equal Channel Angular Pressing (ECAP) process was applied to pure aluminium rod. The effect of the number of passes on hardness and electrical conductivity ECAP samples was investigated. The dimensions of ECAP die for 12 mmm diameter workpieces are designed with intersect angle of 120o. The experiments were carried out by using samples cut from an ingot and a rod and machined to a size of 12 mm in diameter and 50 mm in length. The workpiece was pressed into the ECAP die up to 7 passes at room temperature.After deformation, all samples were subjected to a hardness test, an electrical conductivity test and for optical microscope study. The hardness measurement of the ECAP samples suggested that enhanced hardness would be obtained by repeating ECAP process.Increasing the electrical conductivity of the ECAP samples indicatesthat there is no dislocation formation due to increasing plastic deformation in ECAP process

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