scholarly journals Induction Brazing for Rapid Localized Repair of Inconel 718

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1096
Author(s):  
Aprilia Aprilia ◽  
Jin Lee Tan ◽  
Yongjing Yang ◽  
Sung Chyn Tan ◽  
Wei Zhou
Keyword(s):  
Adverse Effects ◽  
Grain Growth ◽  
Inconel 718 ◽  
Vacuum Furnace ◽  
Slow Process ◽  
Prolonged Heating ◽  
Induction Brazing ◽  
Heating And Cooling ◽  
Short Period ◽  
Different Temperatures

Vacuum furnace has been used for brazing repair of aerospace components, but it is a slow process which typically takes a few hours. The prolonged heating and cooling cycles could cause some adverse effects on the components such as excessive grain growth. A rapid brazing technique using induction coil was studied to evaluate its suitability for localized repair. Induction brazing of Inconel 718 was carried out using AMS 4777 brazing paste at different temperatures (950 °C, 1050 °C and 1150 °C ) for various durations (2 min, 10 min and 20 min). Microstructure and microhardness were evaluated. The experimental results show that brazing at 1050 °C leads to desirable microstructures in a short period of merely 2 min. The study demonstrates the potential application of induction brazing for rapid localized aerospace repair.

scholarly journals Sustainable Modularity Approach to Facilities Development Based on Geothermal Energy Potential

2021 ◽  
Vol 11 (6) ◽  
pp. 2691
Author(s):  
Nataša Ćuković Ignjatović ◽  
Ana Vranješ ◽  
Dušan Ignjatović ◽  
Dejan Milenić ◽  
Olivera Krunić
Keyword(s):  
Geothermal Energy ◽  
Architectural Design ◽  
Pannonian Basin ◽  
Thermal Power ◽  
Chemical Compositions ◽  
Energy Potential ◽  
Southeastern Part ◽  
Geothermal Resources ◽  
Heating And Cooling ◽  
Different Temperatures

The study presented in this paper assessed the multidisciplinary approach of geothermal potential in the area of the most southeastern part of the Pannonian basin, focused on resources utilization. This study aims to present a method for the cascade use of geothermal energy as a source of thermal energy for space heating and cooling and as a resource for balneological purposes. Two particular sites were selected—one in a natural environment; the other within a small settlement. Geothermal resources come from different types of reservoirs having different temperatures and chemical compositions. At the first site, a geothermal spring with a temperature of 20.5 °C is considered for heat pump utilization, while at the second site, a geothermal well with a temperature of 54 °C is suitable for direct use. The calculated thermal power, which can be obtained from geothermal energy is in the range of 300 to 950 kW. The development concept was proposed with an architectural design to enable sustainable energy efficient development of wellness and spa/medical facilities that can be supported by local authorities. The resulting energy heating needs for different scenarios were 16–105 kW, which can be met in full by the use of geothermal energy.

Short-period (Si14 / Si0.75 Ge0.25)20 Superlattices for the Growth of High-quality Si0.75 Ge0.25

2003 ◽  
Vol 765 ◽  
Author(s):  
M.M. Rahman ◽  
T. Tambo ◽  
C. Tatsuyama
Keyword(s):  
Low Temperature ◽  
Alloy Layer ◽  
Buffer Layers ◽  
Threading Dislocations ◽  
Strained Layers ◽  
Temperature Growth ◽  
Low Temperature Growth ◽  
Defect Sites ◽  
Short Period ◽  
Different Temperatures

AbstractIn the present experiment, we have grown 2500-Å thick Si0.75Ge0.25 alloy layers on Si(001) substrate by MBE process using a short-period (Si14/Si0.75Ge0.25)20 superlattice (SL) as buffer layers. In the SL layers, first a layer of 14 monolayers (MLs) of Si (thickness about 20Å) then a thin layer of Si0.75Ge0.25 (thickness 5-6Å) were grown. This Si/(Si0.75Ge0.25) bilayers were repeated for 20 times. The buffer layers were grown at different temperatures from 300-400°C and the alloy layers were then grown at 500°C on the buffer layers. The alloy layer showed low residual strain (about -0.16%) and smooth surface (rms roughness ~15Å) with 300°C grown SL buffer. Low temperature growth of Si in SL layer introduces point defects and low temperature growth of Si1-xGex in SL layer reduces the Ge segregation length, which leads to strained SL layer formation. Strained layers are capable to make barrier for the propagation of threading dislocations and point defect sites can trap the dislocations.

scholarly journals Determination of Grain Growth Kinetics and Assessment of Welding Effect on Properties of S700MC Steel in the HAZ of Welded Joints

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 707 ◽  
Author(s):  
Jaromir Moravec ◽  
Iva Novakova ◽  
Jiri Sobotka ◽  
Heinz Neumann
Keyword(s):  
High Temperature ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Welded Joints ◽  
Material Constant ◽  
Temperature Cycle ◽  
Vacuum Furnace ◽  
Testing Procedures ◽  
Temperature Cycles ◽  
Grain Growth Kinetics

The welding of fine-grained steels is a very specific technology because of the requirement for the heat input limit value. Applying temperature cycles results in an intense grain growth in a high-temperature heat-affected zone (HAZ). This has a significant effect on the changing of strength properties and impact values. The intensity of grain coarsening in the HAZ can be predicted based on the experimentally determined activation energy and material constant, both of which define grain growth kinetics. These quantities, together with real measured welding cycles, can be subsequently used during experiments to determine mechanical properties in a high-temperature HAZ. This paper shows a methodical procedure leading to the obtainment of the material quantities mentioned above that define the grain growth, both at fast and slow temperature cycles. These data were used to define the exposure temperature and the soaking time in a vacuum furnace to prepare test samples with grain sizes corresponding to the high-temperature HAZ of welded joints for the testing procedures. Simultaneously, by means of the thermo-mechanical simulator Gleeble 3500, testing samples were prepared which, due to a temperature gradient, created conditions comparable to those in the HAZ. The experiments were both carried out with the possibility of free sample dilatation and under a condition of zero dilation, which happens when the thermal expansion of a material is compensated by plastic deformation. It has been found that shape of the temperature cycle, maximal achieved cycle temperature, cooling rate, and, particularly, the time in which the sample is in the austenite region have significant effects on the resulting change of properties.

scholarly journals Influence of Various Process Parameters on the Density of Sintered Aluminium Alloys

10.14311/1604 ◽  
2012 ◽  
Vol 52 (4) ◽  
Author(s):  
Mateusz Laska ◽  
Jan Kazior
Keyword(s):  
Sintered Density ◽  
Sintering Temperature ◽  
Compaction Pressure ◽  
Nitrogen Atmosphere ◽  
Chemical Compositions ◽  
Green Density ◽  
Heating And Cooling ◽  
Wide Range ◽  
Different Temperatures ◽  
Metallurgy Industry

This paper presents the results of density measurements carried out on Alumix sintered parts. ECKA Alumix aluminium powders were used because of their wide application in the powder metallurgy industry. The compacts were produced using a wide range of compaction pressures for three different chemical compositions. The compacts were then sintered under a pure dry nitrogen atmosphere at three different temperatures. The heating and cooling rates were the same throughout the entire test. The results showed that the green density increases with compaction pressure, but that sintered density is independent of green density (compaction pressure) for each sintering temperature.

scholarly journals High Temperature Structure in Cool Binary Stars

1996 ◽  
Vol 152 ◽  
pp. 141-145
Author(s):  
A.K. Dupree ◽  
N.S. Brickhouse ◽  
G.J. Hanson
Keyword(s):  
High Temperature ◽  
Binary Stars ◽  
Binary Systems ◽  
Emission Measure ◽  
Temperature Structure ◽  
Differential Emission Measure ◽  
Absolute Size ◽  
Hot Plasma ◽  
Short Period ◽  
Different Temperatures

Strong high temperature emission lines in the EUVE spectra of binary stars containing cool components (Alpha Aur [Capella], 44ι Boo, Lambda And, and VY Ari) provide the basis to define reliably the differential emission measure of hot plasma. The emission measure distributions for the short-period (P ≤ 13 d) binary systems show a high temperature enhancement over a relatively narrow temperature region similar to that originally found in Capella (Dupree et al. 1993). The emission measure distributions of rapidly rotating single stars 31 Com and AB Dor also contain a local enhancement of the emission measure although at different temperatures and width from Capella, suggesting that the enhancement in these objects may be characteristic of rapid rotation of a stellar corona. This feature might be identified with a (polar) active region, although its density and absolute size are unknown; in the binaries Capella and VY Ari, the feature is narrow and it may arise from an interaction region between the components.

Grain Growth during Annealing: Experiments and Modelling

2012 ◽  
Vol 715-716 ◽  
pp. 611-616 ◽  
Author(s):  
M. Candic ◽  
Bao Hui Tian ◽  
Christof Sommitsch
Keyword(s):  
Grain Growth ◽  
Second Phase ◽  
Excellent Correlation ◽  
Grain Sizes ◽  
Second Phase Particles ◽  
Different Temperatures ◽  
Grain Growth Kinetics ◽  
Parameter Approach ◽  
Annealing Experiments ◽  
Two Parameter

In the present work, for the description of grain coarsening, a probabilistic and a deterministic 2D cellular automaton simulation setup were developed. The results of the simulation have been validated by solution annealing experiments of austenitic stainless steel 304L (Fe-18Cr-8Ni) at different temperatures and times. Both cellular automata models show an excellent correlation between the experimental determined data and grain growth kinetics based upon considerations of temperature and second phase particles. Additionally, a two parameter approach of the probabilistic model was implemented, resulting in determining the grain sizes limiting normal and abnormal grains and accurate description of grain growth.

Effects of mesoporous structure on grain growth of nanostructured tungsten oxide

2004 ◽  
Vol 19 (9) ◽  
pp. 2687-2693 ◽  
Author(s):  
Lay Gaik Teoh ◽  
Jiann Shieh ◽  
Wei Hao Lai ◽  
Min Hsiung Hon
Keyword(s):  
Activation Energy ◽  
Surface Area ◽  
Grain Growth ◽  
Pore Diameter ◽  
Mesoporous Structure ◽  
Average Pore ◽  
Transmission Electron ◽  
Show Evidence ◽  
Different Temperatures ◽  
Adsorption Desorption

The effects of mesoporous structure on grain growth were investigated in this study. The synthesis was accomplished using block copolymer as the organic template and tungsten chloride as the inorganic precursor. Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy, x-ray diffractometry (XRD), transmission electron microscopy, and N2 adsorption/desorption isotherms were used to characterize the microstructures obtained for different temperatures. TGA and XRD analyses demonstrate that copolymers were expelled at 150–250 °C, and mesoporous structure was stable up to 350 °C. The pore diameter and the surface area evaluated from the Barrett-Joyner-Halenda model and Brunauer–Emmett–Teller method indicated that the average pore diameter is 4.11 nm and specific surface area is 191.5 m2/g for 250 °C calcination. Arrhenius equation used to calculate the activation energy for grain growth demonstrates that the activation energy for grain growth was about 38.1 kJ/mol before mesostructure collapse and 11.3 kJ/mol after collapse. These results show evidence of two different mechanisms governing the process of grain growth. The presence of the pore can be related to the obstacle for grain growth.

Strain Enhanced High Strength Cu–Ag–Zr Conductors

2009 ◽  
Vol 633-634 ◽  
pp. 707-715 ◽  
Author(s):  
Julia Lyubimova ◽  
Jens Freudenberger ◽  
Alexandere Gaganov ◽  
Hansjörg Klauss ◽  
Ludwig Schultz
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Phase Separation ◽  
Grain Growth ◽  
High Strength ◽  
Homogeneous Material ◽  
Growth Processes ◽  
Heat Treated ◽  
Different Temperatures ◽  
Zr Alloys

Recovery, recrystallisation and grain growth processes as well as the formation of a solid solution and the phase separation of a homogeneous material into a heterogeneous one are observed for Cu-Ag-Zr alloys heat-treated at different temperatures by means of mechanical, electrical and microstructural analyses. Heat treatments are shown to be an effective tool to enhance the strain to failure. If applied between several deformation steps the heat treatment causes an increase of both strain and strength limits.

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