Topic
Shielding gas
About: Shielding gas is a research topic. Over the lifetime, 6697 publications have been published within this topic receiving 58668 citations.
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TL;DR: In this paper, a water-cooled anode calorimeter was designed and manufactured to measure the arc thermal efficiency, which was determined as a function of current, arc length, polarity and gas flow rate for GTAW of mild steel.
Abstract: Arc efficiency of Gas Tungsten Arc Welding (GTAW) was determined by calorimetric method. A water-cooled anode calorimeter was designed and manufactured to measure the arc thermal efficiency, which was determined as a function of current, arc length, polarity and gas flow rate for GTAW of mild steel. With Direct Current Electrode Negative (DCEN) polarity and 5 mm arc length, a thermal efficiency of 67±4% was obtained, which was independent of the welding current. With Direct Current Electrode Positive (DCEP) polarity and 5 mm arc length, arc thermal efficiency was determined as 52±4%. The experimental data show that the arc efficiency decreases from 67% to 58% and 51% as the arc length increases from 5 mm to 11 and 17.5 mm, respectively. The experimental results also show that the arc efficiency is not significantly affected by the shielding gas flow rate.
18 citations
TL;DR: In this paper, the authors measured the process efficiency of laser beam welding as a function of travel speed and temperature measurements were carried out during the bead-on-plate laser welding of mild steel with a focused 2KW CO2 laser beam at various welding travel speeds.
Abstract: The process efficiency of laser beam welding was measured as a function of travel speed Temperature measurements were carried out during the bead‐on‐plate laser welding of mild steel with a focused 2KW CO2 laser beam at various welding travel speeds The laser welding process efficiency (power delivered to work/power in the beam) was calculated from the ratio of the heat content of the welded the specimen to the available laser beam energy (power × time) In the deep penetration welding region at intermediate travel speeds, the laser beam welding process efficiency (equal to the beam absorptance) was about 65%; but it was only about 28% in the shallow penetration region at high travel speeds In deep penetration welding, multiple reflections within the penetration cavity enhance absorptance A calculation based on four reflections within the cavity can account for the observed process efficiency
18 citations
TL;DR: In this article, a tensile test was performed on two different copper canister welds in combination with digital image correlation (DIC) to study hydrogen trapping in the weld material.
18 citations
TL;DR: In this article, a thermal anemometer along with an automated probe-placement system enables the space-resolved measurement of the flow speed and its turbulence in laser powder bed fusion (L-PBF) machines.
Abstract: Purpose
The purpose of this paper is to introduce an approach in measuring the shielding gas flow within laser powder bed fusion (L-PBF) machines under near-process conditions (regarding oxygen content and shielding gas flow).
Design/methodology/approach
The measurements are made sequentially using a hot-wire anemometer. After a short introduction into the measurement technique, the system which places the measurement probe within the machine is described. Finally, the measured shielding gas flow of a commercial L-PBF machine is presented.
Findings
An approach to measure the shielding gas flow within SLM machines has been developed and successfully tested. The use of a thermal anemometer along with an automated probe-placement system enables the space-resolved measurement of the flow speed and its turbulence.
Research limitations/implications
The used single-normal (SN) hot-wire anemometer does not provide the flow vectors’ orientation. Using a probe with two or three hot-films and an improved placement system will provide more information about the flow and less disturbance to it.
Originality/value
A measurement system which allows the measurement of the shielding gas flow within commercial L-PBF machines is presented. This enables the correlation of the shielding gas flow with the resulting parts’ quality.
18 citations
TL;DR: In this paper, the analysis of five different mechanisms of porosity formation during laser melt injection (LMI) technology were performed, and experiments were supported by thermodynamic and fluid-flow analysis.
Abstract: In the present study the analysis of 5 different mechanisms of porosity formation during laser melt injection (LMI) technology were performed. Experiments were supported by thermodynamic and fluid-flow analysis. Special attention should be paid to i. clean the surface of the substrate, ii. use inert shielding gas, iii. use proper particle size and gas velocity, iv. use proper laser power and laser beam velocity to control bath temperature and v. deoxidize the surface of the added particles.
18 citations