Microstructural Characterization by Color Tint Etching of a TRIP-800 Steel Welded by Laser CO2 Process.

2012 ◽  
Vol 1381 ◽  
Author(s):  
G.Y. Pérez-Medina ◽  
P. Zambrano ◽  
H.F. López ◽  
F.A. Reyes-Valdés ◽  
V H. López-Cortés
Keyword(s):  
Retained Austenite ◽  
Process Condition ◽  
Welding Process ◽  
Microstructural Characterization ◽  
Blue Color ◽  
X Ray Diffraction ◽  
Controlled Cooling ◽  
X Ray ◽  
The Impact ◽  
Holding Temperature

ABSTRACTThis paper presents results on the impact of Laser CO2 process variables on the weldability, phase transformations and exhibited tensile properties in a TRIP800 Steel. The microstructures of this steel consist of ferrite, bainite, martensite, and substantial amount of retained austenite, which is obtained by controlled cooling from the intercritical anneling temperature to the isothermal bainitic holding temperature. These steel has been increasingly used in the last 10 years in the automotive industries and for these materials to be used effectively, the influence of material and the Laser CO2 process condition must be clearly understood. Hence, in this work the effect of the welding process on the resultant microstructures and on the exhibited mechanical properties was investigated. Color tint etching applied in welded for AHSS help us to know the phase transformation, the colors of each phase viewed under the microscopy. The weld was etching with Klemm´s 1 solution, in this work; it was found that the bainite is clearly identify by blue color, the martensite brown, yellow ferrite and the retained austenite white. Additional X ray Diffraction (XRD) is employed in characterization to estimate the quantity of retained austenite.

Microstructural and Mechanical Characterization of a TRIP-800 Steel Welded By Laser-CO2 Process

2010 ◽  
Vol 1276 ◽  
Author(s):  
G. Y. Perez-Medina ◽  
P. Zambrano ◽  
H. F. López ◽  
F. A. Reyes-Valdés ◽  
V. H. López-Cortés
Keyword(s):  
Laser Welding ◽  
Automotive Industry ◽  
Annealing Temperature ◽  
Process Condition ◽  
Welding Process ◽  
Controlled Cooling ◽  
The Impact ◽  
Holding Temperature ◽  
Laser Welding Process

AbstractThis paper presents results on the impact of Laser CO2 process variables on the weldability, phase transformations and tensile properties of a TRIP800 Steel. The microstructure of this steel is comprised of ferrite, bainite and retained austenite phases. This is obtained by controlled cooling from the intercritical annealing temperature to the isothermal bainitic holding temperature. These steels have been increasingly used in the last 10 years in the automotive industry and for these materials to be used effectively; the influence of material and the CO2 laser welding process condition must be clearly understood. Hence, in this work the effect of the welding process on the resultant microstructures and on the exhibited mechanical properties is investigated. It is found that the tensile strength of welded specimens falls below 800 MPa and that the elongation becomes 15 % or lower. In turn, this clearly indicates that the implemented laser welding process leads to a reduction in the TRIP800 steel toughness.

Effects of Long-Term Aging in Arsenical Copper Alloys

2015 ◽  
Vol 21 (6) ◽  
pp. 1413-1419 ◽  
Author(s):  
Filipa Pereira ◽  
Rui J. C. Silva ◽  
António M. Monge Soares ◽  
Maria F. Araújo ◽  
Maria J. Oliveira ◽  
...  
Keyword(s):  
Copper Alloys ◽  
Equilibrium Phase ◽  
Microstructural Characterization ◽  
Arsenic Content ◽  
Crystallographic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Impact ◽  
Arsenical Copper

AbstractArchaeological materials present unique records on natural processes allowing the study of long-term material behaviors such as structural modifications and degradation mechanisms. The present work is focused on the chemical and microstructural characterization of four prehistoric arsenical copper artifacts. These artifacts were characterized by micro-energy dispersive X-ray fluorescence spectrometry, optical microscopy, scanning electron microscopy with X-ray microanalysis, micro-X-ray diffraction and synchrotron radiation micro-X-ray diffraction. Cu3As is the expected intermetallic arsenide in arsenical copper alloys, reported in the literature as exhibiting a hexagonal crystallographic structure. However, a cubic Cu3As phase was identified by X-ray diffraction in all of our analyzed archaeological artifacts, while the hexagonal Cu3As phase was clearly identified only in the artifact with higher arsenic content. Occurrence of the cubic arsenide in these particular objects, suggests that it was precipitated due to long-term aging at room temperature, which points to the need of a redefinition of the Cu-As equilibrium phase constitution. These results highlight the importance of understanding the impact of structural aging for the assessment of original properties of archaeological arsenical copper artifacts, such as hardness or color.

scholarly journals The impact of point defects in n-type GaN layers on thermal decomposition of InGaN/GaN QWs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mikolaj Grabowski ◽  
Ewa Grzanka ◽  
Szymon Grzanka ◽  
Artur Lachowski ◽  
Julita Smalc-Koziorowska ◽  
...  
Keyword(s):  
Quantum Wells ◽  
High Temperatures ◽  
Point Defects ◽  
X Ray Diffraction ◽  
Helium Ions ◽  
X Ray ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
The Impact ◽  
Ingan Quantum Wells

AbstractThe aim of this paper is to give an experimental evidence that point defects (most probably gallium vacancies) induce decomposition of InGaN quantum wells (QWs) at high temperatures. In the experiment performed, we implanted GaN:Si/sapphire substrates with helium ions in order to introduce a high density of point defects. Then, we grew InGaN QWs on such substrates at temperature of 730 °C, what caused elimination of most (but not all) of the implantation-induced point defects expanding the crystal lattice. The InGaN QWs were almost identical to those grown on unimplanted GaN substrates. In the next step of the experiment, we annealed samples grown on unimplanted and implanted GaN at temperatures of 900 °C, 920 °C and 940 °C for half an hour. The samples were examined using Photoluminescence, X-ray Diffraction and Transmission Electron Microscopy. We found out that the decomposition of InGaN QWs started at lower temperatures for the samples grown on the implanted GaN substrates what provides a strong experimental support that point defects play important role in InGaN decomposition at high temperatures.

scholarly journals Functional Bionanocomposite Fibers of Chitosan Filled with Cellulose Nanofibers Obtained by Gel Spinning

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1563
Author(s):  
Sofia Marquez-Bravo ◽  
Ingo Doench ◽  
Pamela Molina ◽  
Flor Estefany Bentley ◽  
Arnaud Kamdem Tamo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Cellulose Nanofibers ◽  
Microstructural Characterization ◽  
Fiber Formation ◽  
Fiber Direction ◽  
Composite Fibers ◽  
X Ray Diffraction ◽  
Gel Spinning ◽  
X Ray

Extremely high mechanical performance spun bionanocomposite fibers of chitosan (CHI), and cellulose nanofibers (CNFs) were successfully achieved by gel spinning of CHI aqueous viscous formulations filled with CNFs. The microstructural characterization of the fibers by X-ray diffraction revealed the crystallization of the CHI polymer chains into anhydrous chitosan allomorph. The spinning process combining acidic–basic–neutralization–stretching–drying steps allowed obtaining CHI/CNF composite fibers of high crystallinity, with enhanced effect at incorporating the CNFs. Chitosan crystallization seems to be promoted by the presence of cellulose nanofibers, serving as nucleation sites for the growing of CHI crystals. Moreover, the preferential orientation of both CNFs and CHI crystals along the spun fiber direction was revealed in the two-dimensional X-ray diffraction patterns. By increasing the CNF amount up to the optimum concentration of 0.4 wt % in the viscous CHI/CNF collodion, Young’s modulus of the spun fibers significantly increased up to 8 GPa. Similarly, the stress at break and the yield stress drastically increased from 115 to 163 MPa, and from 67 to 119 MPa, respectively, by adding only 0.4 wt % of CNFs into a collodion solution containing 4 wt % of chitosan. The toughness of the CHI-based fibers thereby increased from 5 to 9 MJ.m−3. For higher CNFs contents like 0.5 wt %, the high mechanical performance of the CHI/CNF composite fibers was still observed, but with a slight worsening of the mechanical parameters, which may be related to a minor disruption of the CHI matrix hydrogel network constituting the collodion and gel fiber, as precursor state for the dry fiber formation. Finally, the rheological behavior observed for the different CHI/CNF viscous collodions and the obtained structural, thermal and mechanical properties results revealed an optimum matrix/filler compatibility and interface when adding 0.4 wt % of nanofibrillated cellulose (CNF) into 4 wt % CHI formulations, yielding functional bionanocomposite fibers of outstanding mechanical properties.

Influence of the Residue of Casting by Lost Wax in the Modulus of Elasticity and Porosity of Concretes

2014 ◽  
Vol 805 ◽  
pp. 343-349
Author(s):  
Carine F. Machado ◽  
Weber G. Moravia
Keyword(s):  
Construction Industry ◽  
Modulus Of Elasticity ◽  
Chemical Characterization ◽  
Microstructural Characterization ◽  
Cement Matrix ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hardened State ◽  
Material Powder

This work evaluated the influence of additions of the ceramic shell residue (CSR), from the industries of Lost Wax Casting, in the modulus of elasticity and porosity of concrete. The CSR was ground and underwent a physical, chemical, and microstructural characterization. It was also analyzed, the environmental risk of the residue. In the physical characterization of the residue were analyzed, the surface area, and particle size distribution. In chemical characterization, the material powder was subjected to testing of X-ray fluorescence (XRF). Microstructural characterization was performed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The residue was utilized like addition by substitution of cement in concrete in the percentages of 10% and 15% by weight of Portland cement. It was evaluated properties of concrete in the fresh and hardened state, such as compressive strength, modulus of elasticity, absorption of water by total immersion and by capillarity. The results showed that the residue can be used in cement matrix and improve some properties of concrete. Thus, the CSR may contribute to improved sustainability and benefit the construction industry.

Cleaner Environment Approach by the Utilization of Low Calcium Wood Ash in Geopolymer Concrete

2021 ◽  
Author(s):  
Kadarkarai Arunkumar ◽  
Muthiah Muthukannan ◽  
Arunachalam Suresh Kumar ◽  
Arunasankar Chithambar Ganesh ◽  
Rangaswamy Kanniga Devi
Keyword(s):  
Fly Ash ◽  
Microstructural Characterization ◽  
Wood Ash ◽  
Geopolymer Concrete ◽  
X Ray Diffraction ◽  
High Potassium ◽  
Waste Wood ◽  
Research Findings ◽  
Research Gap ◽  
The Impact

The waste disposal issues were the most severe problems that could cause global warming, which depletes the environment. The research hypothesis was to find the suitability and sustainability of utilizing the waste by-products in the invention of green geopolymer concrete to eliminate the tremendous effects caused by the wastes. Due to the increased demand for fly ash in recent years, the requirement of high alkaline activators, and elevated temperature for curing, there was a research gap to find an alternative binder. The novelty of this research was to utilize the waste wood ash, which is available plenty in nearby hotels and has an inbuilt composition of high potassium that can act as a self alkaline activator. Waste wood ash procured from the local hotels was replaced with fly ash by 0 to 100% at 10% intervals. The setting and mechanical characteristics were found on the prolonged ages to understand the influence of waste wood ash. Microstructural characterization was found using Scanning Electron Microscope and X-Ray Diffraction Analysis to define the impact of waste wood ash in the microstructure. The research findings showed that replacing 30% waste wood ash with fly ash attained better performance in setting properties and all mechanical parameters. The obtained optimum mix could provide the best alternative for fly ash in geopolymer to eliminate the economic thrust by the requirement of alkaline activators and deploy the environmental impact caused by the waste wood ash.

Ionic conductivity in nanocrystalline Gd doped ceria

2008 ◽  
Vol 1122 ◽  
Author(s):  
Gianguido Baldinozzi ◽  
David Simeone ◽  
Dominique Gosset ◽  
Mickael Dollé ◽  
Georgette Petot-Ervas
Keyword(s):  
Grain Size ◽  
Ionic Conductivity ◽  
Sol Gel ◽  
Doped Ceria ◽  
Narrow Size Distribution ◽  
Conductivity Measurements ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
The Impact

AbstractWe have synthesized Gd-doped ceria polycrystalline samples (5, 10, 15 %mol), having relative densities exceeding 95% and grain sizes between 30 and 160 nm after axial hot pressing (750 °C, 250 MPa). The samples were prepared by sintering nanopowders obtained by sol-gel chemistry methods having a very narrow size distribution centered at about 16 nm. SEM and X-ray diffraction were performed to characterize the sample microstructures and to assess their structures. We report ionic conductivity measurements using impedance spectroscopy. It is important to investigate the properties of these systems with sub-micrometric grains and as a function of their composition. Therefore, samples having micrometric and nanometric grain sizes (and different Gd content) were studied. Evidence of Gd segregation near the grain boundaries is given and the impact on the ionic conductivity, as a function of the grain size and Gd composition, is discussed and compared to microcrystalline samples.

Effect of Different Coiling Temperature on Mechanical Properties in Hot Rolled TRIP Steel

2011 ◽  
Vol 239-242 ◽  
pp. 1092-1095
Author(s):  
Xu Tao Gao ◽  
Ai Min Zhao ◽  
Zheng Zhi Zhao ◽  
Ming Ming Zhang ◽  
Di Tang
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
X Ray Diffraction ◽  
Coiling Temperature ◽  
Experimental Steel ◽  
Transformation Induced Plasticity ◽  
X Ray ◽  
Trip Steels ◽  
Hot Rolled ◽  
Scanning Electron

By means of optical microscopy(OM), scanning electron microscopy(SEM),X-ray diffraction(XRD),And tensile test, Mechanical Properties of hot rolled transformation -induced plasticity (TRIP) steels which were prepared through three different coiling temperature was investigated. Result reveals that the formability index of the experimental steel descends when the coiling temperature becomes low. Different coiling temperature has greater impact on retained austenite. Amount and carbon content of retained austenite in the experimental steel get less with lower coiling temperature.

scholarly journals Microstructural Development in a TRIP-780 Steel Joined by Friction Stir Welding (FSW): Quantitative Evaluations and Comparisons with EBSD Predictions

2016 ◽  
Vol 21 (2) ◽  
pp. 146-155 ◽  
Author(s):  
Gladys Perez Medina ◽  
Hugo Lopez Ferreira ◽  
Patricia Zambrano Robledo ◽  
Argelia Miranda Pérez ◽  
Felipe A. Reyes Valdés
Keyword(s):  
Retained Austenite ◽  
Shear Fracture ◽  
Grain Structure ◽  
Microstructural Development ◽  
Grain Texture ◽  
X Ray Diffraction ◽  
Significant Drop ◽  
X Ray ◽  
Friction Stir ◽  
Lap Shear

Abstract The present work describes the effect of FSW on the result microstructure in the stir zone (SZ), thermo-mechanically affected zone (TMAZ), heat affected zone (HAZ) and base metal (BM) of a TRIP-780 steel. X-ray diffraction (XRD), optical microscopy (OM) and EBSD were used for determinations retained austenite (RA) in the SZ, It was found that the amount of RA developed in SZ was relatively large, (approximately 11% to 15%). In addition, recrystallization and the formation of a grain texture were resolved using EBSD. During FSW, the SZ experienced severe plastic deformation which lead to an increase in the temperature and consequently grain recrystallization. Moreover, it was found that the recrystallized grain structure and relatively high martensite levels developed in the SZ lead to a significant drop in the mechanical properties of the steel. In addition, microhardness profiles of the welded regions indicated that the hardness in both the SZ and TMAZ were relatively elevated confirming the development of martensite in these regions. In particular, to evaluate the mechanical strength of the weld, lap shear tensile test was conducted; exhibited the fracture zone in the SZ with shear fracture with uniformly distributed elongation shear dimples.

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