scholarly journals Beneficial use of hyperbaric process conditions for welding of aluminium and copper alloys

2021 ◽  
Author(s):  
K. Treutler ◽  
S. Brechelt ◽  
H. Wiche ◽  
V. Wesling
Keyword(s):  
Energy Density ◽  
Penetration Depth ◽  
Weld Seam ◽  
Ambient Pressure ◽  
Copper Alloys ◽  
Base Material ◽  
Welding Parameters ◽  
Process Conditions ◽  
Novel Approach ◽  
Core Parameter

AbstractThe joining of components with as few weld layers as possible is an important aspect of weld seam design due to the resulting reduced manufacturing effort and reduced influence of thermal cycles on the base material as well as reduced distortion. For materials with good thermal conductivity, this is not easily possible. The energy density of the arc has been found to be the core parameter for determining the penetration. In the present work, it is shown how the use of a hyperbaric process environment (2 to 16 bar) allows an increase of the energy density of the arc and thus an increase of the penetration depth for selected aluminium and copper alloys. Furthermore, the effects of this novel approach on weld metal metallurgy are presented. It is shown that the penetration depth can be doubled by increasing the ambient pressure. Furthermore, a statistical model for the prediction of the penetration depth depending on the welding parameters will be presented.

The Low-Cycle Fatigue Strength of Laser-Welded Ultra-High-Strength Steel

2011 ◽  
Vol 473 ◽  
pp. 281-289 ◽  
Author(s):  
Markku Keskitalo ◽  
Kari Mäntyjärvi ◽  
Toni Kiuru
Keyword(s):  
Fatigue Strength ◽  
Energy Input ◽  
Weld Seam ◽  
Low Cycle Fatigue ◽  
High Surface ◽  
Base Material ◽  
High Strength ◽  
Welding Parameters ◽  
Light Weight ◽  
Design Strength

The UUltra -high -strength (UHS) steels are used in booms, transport vechicles and other light weight structures. It is well -known that it is possible to achieve a strong weld statically, as the base material, by using laser welding as a weld method [1]. The design strength of the light weight structure is often rather high. In the case of booms and transport vechilevehicles, there can be very high dynamic forces in the structure. Therefore it is necessary to study how much fatigue stress the weld seam can resist and at the same time find the optimal welding parameters. The 4 mm bainitic-martensitic UHS steel was welded with laser without filler material to lasercut seam edges by using different weld parameters. Argon gas was blown by pipe onr coaxial nozzle near the key hole and through a 60 mm gas nozzle after the keyhole. Also, the root side of the weld was shielded with argon. The welds were tested by using the bending fatigue test. The test stresses were 800 MPa and 700 MPa. The fatigue strength results showed that with the laser welded seams, the number of cycles wereas about three times lower than with the base material. The fatigue strength was slightly better in welds which were welded with lower energy input. In the case of the weld seam which was welded with lowest energy input by using 300 mm optics, there was some incomplete penetration due to tooexcessively high surface roughness ofat the weld seam edges.

Impact of Welding Parameters on Weld Seam Properties of Seamless X80 Linepipe Steel Grade

2014 ◽  
Author(s):  
Claas Bruns ◽  
Jörg Wiebe ◽  
Dorothee Niklasch ◽  
Denise Mahn ◽  
Tanja Schmidt
Keyword(s):  
Weld Seam ◽  
Mechanical Test ◽  
Base Material ◽  
Welding Process ◽  
Charpy Impact ◽  
High Strength ◽  
Impact Testing ◽  
Welding Parameters ◽  
Test Results ◽  
Linepipe Steel

The challenging exploration conditions appearing in ultra deep offshore projects promoted the development of high strength linepipe steel grades with yield strength of 80 ksi and higher in recent years. With increasing strength more attention has to be paid to welding procedures to realise the required mechanical properties of the weld seam. The combination of demanding toughness requirements at low temperatures and adequate corrosion resistance of welded joints is a key for complex deep offshore riser and linepipe applications. The welding process was optimised by Vallourec with respect to heat input and preheating temperature for joining seamless quenched and tempered pipes in grade X80. A root welding strategy has been developed particularly with regards to sour service applications. Extensive mechanical test results including Charpy impact testing, hardness, CTOD and SSC testing will be presented. In addition Gleeble trials were carried out using different thermal cycles to simulate multilayer welding. The aim was to improve the understanding of the base material behaviour in the heat affected zone (HAZ) during welding. The microstructure was characterized by LOM, SEM and furthermore hardness and Charpy impact tests were executed. Based on the gathered knowledge and test results welding recommendations and welding strategies for high strength steel X80 seamless line pipes are deduced.

Experimental Investigations on Aluminium Ultrasonic Welding Parameters

2014 ◽  
Vol 657 ◽  
pp. 306-310
Author(s):  
Lăcrămioara Apetrei ◽  
Vasile Rață ◽  
Ruxandra Rață ◽  
Elena Raluca Bulai
Keyword(s):  
Microstructural Analysis ◽  
Base Material ◽  
Welding Process ◽  
Ultrasonic Welding ◽  
Experimental Investigations ◽  
Welding Parameters ◽  
Material Structure ◽  
Welding Temperature ◽  
Wide Range ◽  
Made In

Research evolution timely tendencies, in the nonconventional technologies field, are: manufacture conditions optimization and complex equipments design. The increasing of ultrasonic machining use, in various technologies is due to the expanding need of a wide range materials and high quality manufacture standards in many activity fields. This paper present a experimental study made in order to analyze the welded zone material structure and welding quality. The effects of aluminium ultrasonic welding parameters such as relative energy, machining time, amplitude and working force were compared through traction tests values and microstructural analysis. Microhardness tests were, also, made in five different points, two in the base material and three in the welded zone, on each welded aluminium sample. The aluminum welding experiments were made at the National Research and Development Institute for Welding and Material Testing (ISIM) Timişoara. The ultrasonic welding temperature is lower than the aluminium melting temperature, that's so our experiments reveal that the aluminium ultrasonic welding process doesn't determine the appearance of moulding structure. In the joint we have only crystalline grains deformation, phase transformation and aluminium diffusion.

OCT-Einschweißtiefenüberwachung bei Unterdruck/OCT-based weld penetration monitoring at reduced ambient pressure – Influence of reduced ambient pressure on the OCT signal quality in laser deep penetration welding

2021 ◽  
Vol 111 (11-12) ◽  
pp. 863-868
Author(s):  
Thorsten Mattulat ◽  
Ronald Pordzik ◽  
Peer Woizeschke
Keyword(s):  
Penetration Depth ◽  
Ambient Pressure ◽  
Laser Beam Welding ◽  
In Situ Monitoring ◽  
Deep Penetration ◽  
Weld Penetration ◽  
Laser Deep Penetration Welding ◽  
Deep Penetration Welding ◽  
Non Destructive

Die optische Kohärenztomographie (OCT) erlaubt die zerstörungsfreie In-situ-Überwachung der Einschweißtiefe beim Laserstrahlschweißen. Für dieses Verfahren wird hier der Einfluss von verringerten Umgebungsdrücken auf die Messqualität untersucht. Es wird gezeigt, dass sich bei niedrigerem Umgebungsdruck deutlich größere Signalanteile aus dem Bereich des Bodens der Dampfkapillare zurückerhalten lassen. Auf diese Weise steigen die effektive Messfrequenz und die Erkennbarkeit von Änderungen der Einschweißtiefe.   Optical coherence tomography (OCT) enables non-destructive in-situ monitoring of the weld penetration depth during laser beam welding. For this technology, the influence of reduced ambient pressures on the measurement quality is investigated. It is shown that significantly larger signal components are obtained from the bottom of the vapor capillary at lower ambient pressure increasing the applicable measurement frequency and the detectability of changes in the weld penetration depth.

Possibilities to Apply Friction Stir Processing FSP in Surface Engineering

2021 ◽  
Vol 890 ◽  
pp. 56-65
Author(s):  
Cristian Ciucă ◽  
Lia Nicoleta Boțilă ◽  
Radu Cojocaru ◽  
Ion Aurel Perianu
Keyword(s):  
Aluminum Alloys ◽  
Friction Stir Processing ◽  
Surface Engineering ◽  
Copper Alloys ◽  
Welding Process ◽  
Industrial Applications ◽  
Process Conditions ◽  
Cast Aluminum ◽  
Friction Stir ◽  
Cast Aluminum Alloys

The results obtained by ISIM Timisoara to the development of the friction stir welding process (FSW) have supported the extension of the researches on some derived processes, including friction stir processing (FSP). The experimental programs (the researches) were developed within complex research projects, aspects regarding the principle of the process, modalities and techniques of application, experiments for specific applications, being approached. The paper presents good results obtained by friction stir processing of cast aluminum alloys and copper alloys. The optimal process conditions, optimal characteristics of the processing tools were defined. The complex characterization of the processed areas was done, the advantages of the process applying being presented, especially for the cast aluminum alloys: EN AW 4047, EN AW 5083 and EN AW 7021. The characteristics of the processed areas are compared with those of the base materials. The results obtained are a solid basis for substantiating of some specific industrial applications, especially in the automotive, aeronautical / aerospace fields.

INTERACTION EFFECT BETWEEN BEAM DIAMETER AND ENERGY DENSITY IN LASER-INDUCED TACTILE PERCEPTION

2018 ◽  
Vol 18 (07) ◽  
pp. 1840011
Author(s):  
MI-HYUN CHOI ◽  
HYUNG-SIK KIM ◽  
JI-HUN JO ◽  
JI-SUN KIM ◽  
JAE-HOON JUN ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Energy Density ◽  
Penetration Depth ◽  
Interaction Effect ◽  
Laser Energy ◽  
Tactile Sensation ◽  
Beam Diameter ◽  
Effective Energy ◽  
Effective Energy Transfer ◽  
Response Phase

This study aims to investigate the interaction effect between the beam diameter and energy density, which are perceived as laser-induced tactile perception by humans, by diversely varying the laser parameters, beam diameter, and energy. Eight healthy male college students of 23.5[Formula: see text][Formula: see text][Formula: see text]1.7 years participated in the study. The range of the beam diameter of the displayed laser stimulation was between 0.03[Formula: see text]mm and 8[Formula: see text]mm, and a total of 21 sizes were displayed. The laser energy was sequentially displayed from the minimum energy that can be displayed by one beam diameter to the maximum energy range that does not exceed the maximum permissible exposure (MPE) level since the energy varies according to the beam diameter. The laser energy was controlled by an optical density ([Formula: see text]) filter and was measured by an optical power meter (energy meter). Furthermore, the beam diameter was adjusted by moving the lens, which was confirmed with the beam profiler. The experimental test consists of the control phase (19[Formula: see text]s), stimulus phase (7[Formula: see text]s), and response phase (4[Formula: see text]s); the total duration of the test was 30[Formula: see text]s. The stimulus phase is the period in which stimulation was displayed on the skin through laser irradiation, and the stimulation was displayed by changing the beam diameter and the energy from the laser. The total number of beam diameter and energy pairs displayed to the subjects was 113 and 5 trials of irradiation were conducted for each pair. Stimulation perception response was recorded by pressing the response buttons during the response phase, and the responses were predefined as “no feeling,” “tactile sensation”, and “pain.” Through the extracted response data from the response phase, the beam diameter and energy density pair in which more than 50% of the subjects responded as having perceived tactile sensation were selected from the possible laser energy that could be displayed from one beam diameter. The simulation results showed that increasing the beam diameter increased the penetration depth, indicating an effective energy transfer to the skin. Therefore, increasing the beam diameter results in increased scattering, and hence increased penetration depth, and ultimately a more effective energy transfer. Therefore, increased beam diameter results in higher energy transfer efficiency, indicating that the required energy density by more than 50% of the subjects to perceive tactile sensation decreased.

scholarly journals Extraction of Ta and Nb from a Coltan Bearing Ore by Means of Ammonium Bifluoride Fluorination and Sulfuric Acid Leaching

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1392
Author(s):  
Alidor Shikika ◽  
Francois Zabene ◽  
Fabrice Muvundja ◽  
Mac C. Mugumaoderha ◽  
Julien L. Colaux ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Acid Leaching ◽  
Environmental Benefits ◽  
Process Conditions ◽  
Sulfuric Acid Leaching ◽  
Mechanical Agitation ◽  
Ammonium Bifluoride ◽  
Novel Approach ◽  
Pre Treatment ◽  
Subsequent Acid

A novel approach for Ta and Nb extraction consisting of the pre-treatment of a coltan-bearing ore with an ammonium bifluoride sub-molten salt and subsequent acid leaching has been studied. The effects from ore granulometry, ammonium bifluoride (ABF) to ore mass ratio, temperature and duration of fluorination on the degree of Ta and Nb extraction were examined. The ABF to ore ratio and process temperature were found to have the most pronounced impact on extraction efficiency. The following optimal process conditions were determined: ore granulometric fraction (−75 + 45 µm), ABF-ore (5/1), fluorination temperature (200 °C) and fluorination time (2.5 h). Maintaining these parameters enabled about 94% of Ta and 95% of Nb to be brought into solution during the sulfuric-acid-leaching stage. A comparison of the proposed method with previously reported studies suggests that due to the effects of mechanical agitation and the recirculation of the HF-containing gaseous phase back into the process, the dosage rate of ABF at the fluorination stage could be reduced significantly without sacrificing the overall recovery of Ta and Nb. In such a way, the approach could offer added environmental benefits since release of fluoride-containing effluents into the environment could be limited.

scholarly journals Flashboiling atomization in nozzles for GDI engines

2017 ◽  
Author(s):  
Sebastian Bornschlegel ◽  
Chris Conrad ◽  
Lisa Eichhorn ◽  
Michael Wensing
Keyword(s):  
Penetration Depth ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Ambient Pressure ◽  
Rapid Expansion ◽  
Gasoline Direct Injection ◽  
Coolant Temperature ◽  
Concentrated Mass ◽  
Flash Boiling ◽  
Gdi Engines

Flashboiling denotes the phenomenon of rapid evaporation and atomization at nozzles, which occurs when fluidsare injected into ambient pressure below their own vapor pressure. It happens in gasoline direct injection (GDI) engines at low loads, when the cylinder pressure is low during injection due to the closed throttle valve. The fuel temperature at the same time approaches cylinder head coolant temperature due to the longer dwell time of the fuel inside the injector. Flash boiling is mainly beneficial for atomization quality, since it produces small droplet sizes and relative broad and homogenous droplet distributions within the spray. Coherently, the penetration depth normally decreases due to the increased aerodynamic drag. Therefore the thermal properties of injectors are often designed to reach flash boiling conditions as early as possible. At the same time, flash boiling significantly increases the risk of undesired spray collapsing. In this case, neighbouring jets converge and form a single jet. Due to the now concentrated mass, penetration depth is enhanced again and can lead to liner or piston wetting in addition to the overall diminished mixture formation.In order to understand the underlying physics, it is important to study the occurring phenomena flashboiling and jet-to-jet interacting i.e. spray collapsing separately. To this end, single hole injectors are built up to allow for an isolated investigation of flashboiling. The rapid expansion at the nozzle outlet is visualized with a microscopic high speed setup and the forces that lead to the characteristic spray expansion are discussed. Moreover, the results on the macroscopic spray in terms of penetration, cone angles and vapor phase are shown with a high speed Schlieren setup. Resulting droplet diameters and velocities are measured using LDA/PDA.As a result, we find a comprehensive picture of flash boiling. The underlying physics can be described and discussed for the specific case of high pressure injection at engine relevant nozzle geometries and conditions, but independently from neighbouring jets. These findings provide the basis to understand and investigate flashboilingand jet-to-jet interaction as distinct, but interacting subjects rather than a combined phenomenon.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4750 

Friction Stir Welding of Elements Made of Cast Aluminium Alloys

2014 ◽  
Vol 59 (1) ◽  
pp. 385-392
Author(s):  
B. Rams ◽  
A. Pietras ◽  
K. Mroczka
Keyword(s):  
Friction Stir Welding ◽  
Aluminium Alloy ◽  
Aluminium Alloys ◽  
Welding Parameters ◽  
Process Conditions ◽  
Friction Stir ◽  
Seam Weld ◽  
Cast Aluminium ◽  
Weld Structure ◽  
Welding Stability

Abstract The article presents application of FSW method for joining elements made of cast aluminium alloys which are hardly weldable with other known welding techniques. Research’s results of plasticizing process of aluminium and moulding of seam weld during different FSW process’ conditions were also presented. Influence of welding parameters, shape and dimensions of tool on weld structure, welding stability and quality was examined. Application of FSW method was exemplified on welding of hemispheres for valves made of cast aluminium alloy EN AC-43200.

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