scholarly journals Effect of pulse frequency on arc behavior and droplet transfer of 2198 Al–Li alloy by ultrahigh-frequency pulse AC CMT welding

2019 ◽  
Vol 8 (5) ◽  
pp. 3950-3958 ◽  
Author(s):  
Dianlong Wang ◽  
Chaofeng Wu ◽  
Yingchao Suo ◽  
Liwei Wang ◽  
Zhimin Liang
Keyword(s):  
Pulse Frequency ◽  
Ultrahigh Frequency ◽  
Droplet Transfer ◽  
Arc Behavior ◽  
Cmt Welding ◽  
Frequency Pulse

scholarly journals Effect of Pulse Frequency on Microstructure and Mechanical Properties of 2198 Al-Li Alloy Joints Obtained by Ultrahigh-Frequency Pulse AC CMT Welding

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 79 ◽  
Author(s):  
Liwei Wang ◽  
Yingchao Suo ◽  
Chaofeng Wu ◽  
Dianlong Wang ◽  
Zhimin Liang
Keyword(s):  
Tensile Strength ◽  
Welded Joints ◽  
Electromagnetic Force ◽  
Molten Pool ◽  
High Performance ◽  
Pulse Frequency ◽  
Ultrahigh Frequency ◽  
Cold Metal Transfer ◽  
Cold Metal ◽  
Frequency Pulse

In this study, 2198 Al-Li alloy, a low density and high-performance material for aerospace equipment, was welded using ultrahigh-frequency pulse alternating current with cold metal transfer (UHF-ACCMT). Influence of different ultrahigh-frequency on the formation, porosity, microstructure, microhardness and tensile strength of the welded joints were investigated. The results showed that the coupled ultrahigh-frequency current generated electromagnetic force to stir the liquid metal of molten pool. The weld formation became much better with metallic luster and uniform ripples at frequency of 60 kHz and 70 kHz. The porosity was the minimum at frequency of 60 kHz. Furthermore, the molten pool was scoured and stirred by the electromagnetic force which provided the thermal and dynamic conditions for nucleation and grain refinement, the width of fine equiaxed grain zone became larger, and the number of equiaxed non-dendrite grains increased. With the grain refining and crystallize transition, the average microhardness and tensile strength of the joints at frequency of 60 kHz reached up the highest value, 116 HV0.1 and 338 MPa, respectively. The fracture of the welded joints presented the characteristics of quasi-cleavage fracture.

Effect of pulse frequency on droplet transfer and weld formation in local dry underwater welding

2021 ◽  
Vol 68 ◽  
pp. 1726-1734
Author(s):  
Zhenmin Wang ◽  
Kai Pei ◽  
Leigang Han ◽  
Haodong Wu ◽  
Sanbao Lin ◽  
...  
Keyword(s):  
Pulse Frequency ◽  
Droplet Transfer ◽  
Underwater Welding ◽  
Weld Formation

Pulsed-DC Electrospray for Biopolymer Particle Production

2009 ◽  
Vol 1239 ◽  
Author(s):  
Cho-Hui Lim ◽  
Kiersten R Schierbeek ◽  
Michael E Mullins
Keyword(s):  
Pulse Width ◽  
Particle Production ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Process Conditions ◽  
High Duty Cycle ◽  
Pulsed Dc ◽  
High Pulse ◽  
Long Pulse ◽  
Frequency Pulse

AbstractPLLA microparticles were successfully fabricated via pulsed-DC electrospray. In this study, we investigated the effect of the pulsed voltage characteristics (e.g. pulse frequency, pulse amplitude and pulse width) on the particle’s size. We found that pulse frequency, pulse amplitude, pulse width, and the combinations of these factors had a statistically significant effect on the particle’s size. The process conditions to obtain smaller particles with uniform shape and size are a low pulse frequency, high pulse amplitude, and long pulse width (or a high duty cycle).

Kisspeptin 10 Infusion Increases LH Pulse Frequency, Pulse Size and Testosterone Secretion in Men

2011 ◽  
pp. OR35-5-OR35-5
Author(s):  
Jyothis T George ◽  
Johannes D Veldhuis ◽  
Richard A Anderson ◽  
Robert P Millar
Keyword(s):  
Pulse Frequency ◽  
Testosterone Secretion ◽  
Frequency Pulse

scholarly journals Detection of tiny amounts of fissile materials in large-sized containers with radioactive waste

2018 ◽  
Vol 170 ◽  
pp. 05005
Author(s):  
V.F. Batyaev ◽  
S.V. Skliarov
Keyword(s):  
Radioactive Waste ◽  
Neutron Flux ◽  
Thermal Neutron Flux ◽  
Pulse Frequency ◽  
Matrix Type ◽  
Neutron Interrogation ◽  
Interrogation Technique ◽  
Non Destructive ◽  
Frequency Pulse ◽  
Param Eters

The paper is devoted to non-destructive control of tiny amounts of fissile materials in large-sized containers filled with radioactive waste (RAW). The aim of this work is to model an active neutron interrogation facility for detection of fissile ma-terials inside NZK type containers with RAW and determine the minimal detectable mass of U-235 as a function of various param-eters: matrix type, nonuniformity of container filling, neutron gen-erator parameters (flux, pulse frequency, pulse duration), meas-urement time. As a result the dependence of minimal detectable mass on fissile materials location inside container is shown. Nonu-niformity of the thermal neutron flux inside a container is the main reason of the space-heterogeneity of minimal detectable mass in-side a large-sized container. Our experiments with tiny amounts of uranium-235 (<1 g) confirm the detection of fissile materials in NZK containers by using active neutron interrogation technique.

Parameters of the electric strength of air in a surface antenna during the emission of an ultrahigh-frequency pulse with a trapezoidal envelope

2020 ◽  
Vol 23 (3) ◽  
pp. 62-67
Author(s):  
Aleksey A. Volkov
Keyword(s):  
Pulse Duration ◽  
Electric Strength ◽  
Peak Amplitude ◽  
Breakdown Field ◽  
Ultrahigh Frequency ◽  
Energy Parameters ◽  
Microwave Generators ◽  
Powerful Microwave ◽  
Frequency Pulse

On the basis of the breakdown criterion and the equation of continuity of electrons in air, the amplitude and energy parameters of the electric strength of air in the surface antenna of a powerful microwave relativistic generator are determined when pulses are emitted with a trapezoidal envelope. Triangular and rectangular envelopes were considered as boundary cases of a trapezoidal envelope. The dependence of the parameters of electric strength on the shape of the envelope has been established. The calculation of the dependences of the breakdown field and the maximum permissible energy in a flat aperture on the pulse duration in the range of realizable durations of powerful relativistic microwave generators is carried out. For the same duration, the largest breakdown field has a pulse with a triangular envelope, and the smallest a pulse with a rectangular envelope. Wherein a pulse with a triangular envelope has the lowest maximum permissible energy, and a rectangular one has the highest. The relationships between the maximum permissible energy and the breakdown field for the pulses under consideration are determined. With the same maximum permissible peak amplitude, the highest energy has a pulse with a triangular envelope, and the smallest a pulse with a rectangular envelope.

Microstructure and Fatigue Property of Ti–6Al–4V by Ultrahigh Frequency Pulse Welding

2016 ◽  
Vol 139 (4) ◽  
Author(s):  
Mingxuan Yang ◽  
Hao Zheng ◽  
Bojin Qi ◽  
Zhou Yang
Keyword(s):  
Fusion Zone ◽  
Low Cycle Fatigue ◽  
Fatigue Property ◽  
Ultrahigh Frequency ◽  
Butt Welding ◽  
Gas Tungsten Arc ◽  
Secondary Cracks ◽  
Gtaw Process ◽  
Pulse Welding ◽  
Frequency Pulse

Butt welding tests of 1.5 mm thickness Ti–6Al–4V were treated by conventional gas tungsten arc welding (C-GTAW) and ultrahigh frequency pulse GTAW (UHFP-GTAW). The low cycle fatigue (LCF) experiments were conducted on the welded joints. The results of fatigue experiment showed that the number of fatigue cycles was increased with UHFP-GTAW. Changes in the microstructure resulting from reduced heat input were expected to enhance the fatigue propagation resistance. The morphology of the martensites in fusion zone was smaller compared to C-GTAW process, and a larger distribution density of basketweave structure was also obtained by UHFP-GTAW. Furthermore, the decreased fatigue crack rate was accompanied as the increased grain boundaries produced by the reduced grain size in fusion zone. Observation of fatigue fractographs revealed that the UHFP-GTAW has obvious slip traces at fatigue initiation sites and more deep secondary cracks in the crack propagation regions associated with the smaller dimples of final fracture zones. The proportion of propagation regions was much larger than C-GTAW. As a result, it can be considered as the representation of the improvement in ductility.

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