Comparison between methods measuring arc efficiency of gas tungsten arc welding

Fujiyama, Shoji; Shigeta, Masaya; Tanaka, Manabu

doi:10.1080/13621718.2021.1921101

Cited by 12 publications

(4 citation statements)

References 12 publications

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“…Liquid nitrogen was filled up to 300 mm from an inner bottom of the dewar and drop height from the liquid nitrogen surface was 199 mm, which was minimum distance because of mechanical design. It was confirmed that heat loss of forced convection and thermal radiation during free fall of base metals was negligible 17) . The measurement procedure was automated in order to remove uncertainty of manual operations.…”

Section: Methodsmentioning

confidence: 80%

“…As mentioned by Fujiyama et al 17) , however, it is inferred that heat input to entire base metal depends on temperature gradient in the base metal (surface temperature of the base metal can also affect arc efficiency) and arc efficiency and temperature distribution are indivisible. Moreover, if one think using the value of arc efficiency, not only the instantaneous heat input but also heat input in realistic welding conditions would be required in validation phase of numerical simulation.…”

Section: Definition Of Arc Efficiencymentioning

confidence: 99%

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Dependency of arc efficiency on welding current in gas metal arc welding

Fujiyama

Komen

Tanaka

2022

QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY

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Arc efficiency of gas metal arc welding was measured in changing welding current. Increasing welding current, arc efficiency showed convex curve. Estimating amount of heat transferred by metal droplets, it was concluded that increase of arc efficiency in the welding current less than 186 A was caused by heat of metal transfer, while decrease in the welding current more than 186 A was caused by overwhelming arc radiation.

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Section: Methodsmentioning

confidence: 80%

Section: Definition Of Arc Efficiencymentioning

confidence: 99%

Dependency of arc efficiency on welding current in gas metal arc welding

Fujiyama

Komen

Tanaka

2022

QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY

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“…where H is heat input per unit length (J/mm), I is welding current (A), V is arc voltage (V), S is travel speed (mm/s) and η is arc efficiency (60% [54]). The plate after the root pass is depicted in Figure 1d.…”

Section: Methodsmentioning

confidence: 99%

Influence of PWHT Parameters on the Mechanical Properties and Microstructural Behavior of Multi-Pass GTAW Joints of P92 Steel

et al. 2022

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The 9% Cr steels were developed for ultra-supercritical (USC) power plants to meet the requirements of high operating temperature and pressure. These steels are produced to operate at high temperatures where impact toughness is not a concern; however, it becomes important for the welded joints to have good impact toughness at room temperature for manufacturing. The present work investigates the effect of the post-weld heat treatment (PWHT) parameters, i.e., temperature and time, on the impact toughness of multi-pass gas tungsten arc welded (GTAW) joints of ferritic/martensitic grade P92 steel. The microstructural evolution in welded joints given varying post-weld temperatures and times was studied. The lath martensitic structure of the weld metal for the as-welded joints resulted in high hardness and low impact toughness. The weld fusion zone toughness was 12 J, which was lower than the minimum specified values of 41 J (ASME standards) and 47 J (EN ISO 3580:2017). The PWHT temperature and time were found to have a significant effect on the impact toughness of the weld metal. A drastic increase in the impact toughness of the weld metal was noticed, which was attributed to lath break-up, reduction in dislocation density and reduction in solid solution hardening. The maximum impact toughness of 124 J was measured for PWHT temperature and time of 760 °C and 120 min, respectively. The effect of PWHT parameters on tensile strength was also investigated, and test results showed that the joint was safe for USC boiler application as it failed from the region of the P92 base metal. The variation in microstructural evolution along the weldments resulted in hardness variation. PWHT led to homogeneity in microstructure and, ultimately, reduction in hardness value. According to the study, the optimum temperature and time for PWHT of a GTAW joint of P92 steel were found to be 760 °C and 120 min, respectively.

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“…127) Additionally, the thermal energy transferred from an arc plasma to a base metal was measured for a GTA welding condition. 128) Despite those efforts, it is still difficult to measure the temperature and flow velocity in the molten metals.…”

Section: Mpbulkmentioning

confidence: 99%

Progress of computational plasma fluid mechanics

Shigeta

2023

Jpn. J. Appl. Phys.

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This article reviews and discusses the recent progresses of studies with the concept of “Computational plasma fluid mechanics”. Computational demonstrations show that the inhouse simulation codes such as PLASTIPC (PLasma All-Speed Turbulence with Implicit Pressure Code) have captured hydrodynamic instabilities and reproduced flow dynamics in thermal plasma – nonionized gas coexisting systems. A unique method has made it feasible to study collective growth of binary alloy nanoparticles by numerical analysis. SPH (Smoothed Particle Hydrodynamics) method with incompressibility modification has achieved complex behaviors of molten metal involving phase change, flow, heat transport, material mixing, and large deformation during arc welding. It is essential to study thermal plasma processes as comprehensive fluid systems in which hot plasma, cold nonionized gas, and materials coexist. The viewpoint and approaches of fluid mechanics as well as plasma physics are indispensable. Computational study will play a more important role in giving us new and deeper insights.

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Comparison between methods measuring arc efficiency of gas tungsten arc welding

Cited by 12 publications

References 12 publications

Dependency of arc efficiency on welding current in gas metal arc welding

Dependency of arc efficiency on welding current in gas metal arc welding

Influence of PWHT Parameters on the Mechanical Properties and Microstructural Behavior of Multi-Pass GTAW Joints of P92 Steel

Progress of computational plasma fluid mechanics

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