scholarly journals Analysis of the Drawing Process of Small-Sized Seam Tubes

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 709 ◽  
Author(s):  
Alexander Schrek ◽  
Alena Brusilová ◽  
Pavol Švec ◽  
Zuzana Gábrišová ◽  
Ján Moravec
Keyword(s):  
Gas Flow ◽  
Weld Line ◽  
Small Diameter ◽  
Inert Gas ◽  
Limiting Factors ◽  
Protective Atmosphere ◽  
Drawing Process ◽  
Tube Production ◽  
Process Stability ◽  
Significant Temperature

This article is focused on an analysis of factors negatively affecting the tube production process of tubes made from austenitic stainless steel with a very small diameter of ϕ 0.34 mm. The analysis was concentrated on factors that affect the drawing process stability of the seam tubes where the desired final dimensions—a diameter of ϕ 0.34 mm and a wall thickness of 0.057 mm—are limiting factors. Seam tubes made from steel 1.4306 and 1.4301, from producers KT and EW with a longitudinal weld line made by tungsten inert gas (TIG) welding, were used as blanks for constituent drawing operations. It is desirable to provide sufficient inert gas flow and cooling during the formation of a weld joint in a protective atmosphere chamber. A significant temperature gradient prevents the formation of undesirable Cr23C6 carbides in the heat-affected zone (HAZ) which negatively affects the plasticity and formability of the steel and is the cause of technological fractures.

Effect of Inert Gas Flow Nature on SiC Microtube Synthesis

2005 ◽  
pp. 220-225 ◽  
Author(s):  
Jae Won Kim ◽  
Seoung Soo Lee ◽  
Dong Ho Park ◽  
Yeon Gil Jung ◽  
Je Hyun Lee ◽  
...  
Keyword(s):  
Gas Flow ◽  
Inert Gas

Semi-Solid Slurry Casting Using Gas Induced Semi-Solid Technique to Enhance the Microstructural Characteristics of Al-4.3Cu Alloy

2019 ◽  
Vol 285 ◽  
pp. 253-258
Author(s):  
M. Abdi ◽  
S.G. Shabestari
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Temperature Drop ◽  
Inert Gas ◽  
Globular Structure ◽  
Cast Sample ◽  
A206 Alloy ◽  
Gas Purging ◽  
Semi Solid ◽  
Conventionally Cast

Semi-solid processing of Al-4.3%Cu (A206) alloy was performed by Gas Induced Semi-Solid (GISS) process in different condition. The flow rate of argon gas, starting temperature for gas purging (the temperature of superheated-melt) and the duration of gas purging were three key process variables which were changed during this investigation. It was found that inert gas purging near liquidus, significantly, led to the microstructural modification from fully dendritic to globular structure. Thermal analysis was successfully implemented through CA-CCTA technique to understand the cause of the microstructure change during GISS process. The results showed that gas purging into the melt leads to temperature drop of the melt to its liquidus just after a few seconds from start of gas purging. In fact, copious nucleation was induced by cooling effect of inert gas bubbles. Microstructural features were characterized in semi-solid as well as on conventionally cast samples. The optimum gas purging temperature, injection time, and inert gas flow rate was determined in semi-solid processing to obtain the best globularity in the microstructure of a long freezing range alloy. However, the microstructure of the conventionally cast sample was fully dendritic with shrinkage which affects the soundness of casting products.

Respiratory and inert gas exchange during high-frequency ventilation

1982 ◽  
Vol 52 (3) ◽  
pp. 683-689 ◽  
Author(s):  
H. T. Robertson ◽  
R. L. Coffey ◽  
T. A. Standaert ◽  
W. E. Truog
Keyword(s):  
Gas Exchange ◽  
High Frequency ◽  
Gas Flow ◽  
Inert Gases ◽  
Inert Gas ◽  
High Frequency Ventilation ◽  
Physiological Dead Space ◽  
Volume Ventilation ◽  
Frequency Ventilation ◽  
Carrier Gases

Pulmonary gas exchange during high-frequency low-tidal volume ventilation (HFV) (10 Hz, 4.8 ml/kg) was compared with conventional ventilation (CV) and an identical inspired fresh gas flow in pentobarbital-anesthetized dogs. Comparing respiratory and infused inert gas exchange (Wagner et al., J. Appl. Physiol. 36: 585--599, 1974) during HFV and CV, the efficiency of oxygenation was not different, but the Bohr physiological dead space ratio was greater on HFV (61.5 +/- 2.2% vs. 50.6 +/- 1.4%). However, the elimination of the most soluble inert gas (acetone) was markedly enhanced by HFV. The increased elimination of the soluble infused inert gases during HFV compared with CV may be related to the extensive intraregional gas mixing that allows the conducting airways to serve as a capacitance for the soluble inert gases. Comparing as exchange during HFV with three different density carrier gases (He, N2, and Ar), the efficiency of elimination of Co2 or the intravenously infused inert gases was greatest with He-O2. However, the alveolar-arterial partial pressure difference for O2 on He-O2 exceeded that on N2-O2 by 5.4 Torr during HFV. The finding agrees with similar observations during CV, suggesting that this aspect of gas exchange is not substantially altered by HFV.

Part II. Research on the Performance of a Type of Internally Air-cooled Turbine Blade

1953 ◽  
Vol 167 (1) ◽  
pp. 351-370 ◽  
Author(s):  
D. G. Ainley
Keyword(s):  
Gas Flow ◽  
Thermal Stresses ◽  
Turbine Blades ◽  
Small Diameter ◽  
Rotor Blades ◽  
Air Cooling ◽  
Gas Temperature ◽  
Flow Through ◽  
Cooling Air ◽  
Practical Feasibility

A comprehensive series of tests have been made on an experimental single-stage turbine to determine the cooling characteristics and the overall stage performance of a set of air-cooled turbine blades. These blades, which are described fully in Part I of this paper had, internally, a multiplicity of passages of small diameter along which cool air was passed through the whole length of the blade. Analysis of the, test data indicated that, when a quantity of cooling air amounting to 2 per cent, by weight, of the total gas-flow through the turbine is fed to the row of rotor blades, an increase in gas temperature of about 270 deg. C. (518 deg. F.) should be permissible above the maximum allowable value for a row of uncooled blades made from the same material. The degree of cooling achieved throughout each blade was far from uniform and large thermal stresses must result. It appears, however, that the consequences of this are not highly detrimental to the performance of the present type of blading, it being demonstrated that the main effect of the induced thermal stress is apparently to transfer the major tensile stresses to the cooler (and hence stronger) regions of the blade. The results obtained from the present investigations do not represent a limit to the potentialities of internal air-cooling, but form merely a first exploratory step. At the same time the practical feasibility of air cooling is made apparent, and advances up to the present are undoubtedly encouraging.

High-temperature annealing of macroporous silicon in an inert-gas flow

2017 ◽  
Vol 51 (9) ◽  
pp. 1153-1163 ◽  
Author(s):  
E. V. Astrova ◽  
N. E. Preobrazhenskiy ◽  
S. I. Pavlov ◽  
V. B. Voronkov
Keyword(s):  
High Temperature ◽  
Gas Flow ◽  
Inert Gas ◽  
Macroporous Silicon ◽  
High Temperature Annealing

Effect of Inert Gas Flow Rate on Homogenization and Inclusion Removal in a Gas Stirred Ladle

2010 ◽  
Vol 81 (12) ◽  
pp. 1056-1063 ◽  
Author(s):  
M. Ek ◽  
L. Wu ◽  
P. Valentin ◽  
D. Sichen
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Inert Gas ◽  
Gas Flow Rate ◽  
Inclusion Removal

Numerical Modeling of CO2 Splitting in High-Temperature Solar-Driven Oxygen Permeation Membrane Reactors

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Heng Pan ◽  
Youjun Lu ◽  
Liya Zhu
Keyword(s):  
Membrane Reactor ◽  
Continuous Production ◽  
Oxygen Permeation ◽  
Conversion Ratio ◽  
Inert Gas ◽  
Limiting Factors ◽  
Co2 Conversion ◽  
Permeable Membrane ◽  
Concentrated Solar Energy ◽  
Oxygen Permeation Membrane

Abstract H2/CO production via H2O/CO2 splitting powered by concentrated solar energy is a promising pathway for energy conversion/storage. Oxygen permeable membrane reactor serves as an alternative reactor concept for realizing this chemical path with the advantages of continuous production, easy integration, and high product selectivity. In this paper, a mathematical model of steady-state mass and heat transfer coupled with reaction kinetics in the oxygen permeation membrane reactor was established. CO2 splitting in the ceria membrane reactor was simulated and the effects of various factors, including inert/CO2 flow configurations, reaction conditions, and geometric parameters of the membrane, on the CO2 conversion process, were studied. The increase of operating temperature could effectively improve the CO2 conversion ratio, and the effect of decreasing the oxygen pressure of the inert gas is very limited. The oxygen accumulation in the inert gas could lead to considerably high inert demand. Furthermore, conversion-limiting factors were studied under different conditions and there are two critical rate constants of reactions signifying a transition from a chemical kinetics limited conversion to oxygen diffusion limited conversion. This work helps guide reactor design and operate toward achieving the maximum CO2 conversion ratio.

Accelerated Cooling of Optical Fiber

1989 ◽  
Vol 172 ◽  
Author(s):  
S. Kyriacou ◽  
C. E. Polymeropoulos ◽  
V. Sernas
Keyword(s):  
Optical Fiber ◽  
Gas Flow ◽  
Small Diameter ◽  
Experimental Results ◽  
Accelerated Cooling ◽  
Fiber Motion

AbstractA novel apparatus for accelerated cooling of optical fiber has been used at different fiber speeds using Nitrogen and Helium as the cooling gases. The gas flow was counter to the direction of the fiber motion inside a small diameter tube. The experimental results show significant improvement over natural cooling, as well as over available transverse cooling.

Enhancing fatigue resistance of activated tungsten inert gas welded UNS S32750 super duplex stainless steel by optimizing its technological properties

2020 ◽  
pp. 1-11
Author(s):  
A. Arunmani ◽  
T. Senthilkumar
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Duplex Stainless Steel ◽  
Fatigue Resistance ◽  
Process Parameters ◽  
Gas Flow ◽  
Welding Process ◽  
Travel Speed ◽  
Inert Gas ◽  
Super Duplex Stainless Steel

In engineering industries and heavy manufacturing plants, fatigue life of joints plays a pivotal role in determining the overall life span of the welded joint. In this paper, an advanced fusion joining technique, namely activated tungsten inert gas welding, was used for joining UNS S32750 super duplex stainless steel, with ZnO as activation flux. For the enhancement of fatigue resistance of joints, important welding process parameters were fluctuated according to a developed central composite design model. Empirical relationships were developed between the process parameters and the fatigue strength of the joints, which was correlated with the number of cycles to failure (NCF). Using analysis of variance, the significance of the developed fatigue model was ascertained. Using response surface methodology, optimization of process parameters for enhancement of fatigue resistance was done. It was observed that at the optimized activated tungsten inert gas weld process parameters of travel speed of welding torch at 69.85 mm/min, weld current at 125.20 A, and shielding gas flow rate at 14.77 L/min, a high fatigue life of 7.66396 × 108 NCF was obtained and the model was validated to very high predictability. Microstructural variations in the fatigue-tested specimens were evaluated for identifying the grain modifications.

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