A novel strategy to improve melting efficiency and arc stability in underwater FCAW via contact tip air chamber

Assunção, Marcelo Teodoro; Bracarense, Alexandre Queiroz

doi:10.1016/j.jmapro.2023.08.054

Cited by 6 publications

(6 citation statements)

References 26 publications

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“…The constant section from the contact tip to the substrate materials, referred to as contact-tip-to-work distance, can be considered as a parallel-connected chain of individual sections of the electrode extension-arc column, which dynamically changes due to mutual compensation. Increasing the length of the electrode extension section leads to heating of the flux-cored wire electrode in front of the tip, due to Joule heat [101,102]. The presence of an additional heat source (exothermic reaction) introduces changes into the energy distribution.…”

Section: Discussionmentioning

confidence: 99%

Effect of Exothermic Additions in Core Filler on Arc Stability and Microstructure during Self-Shielded, Flux-Cored Arc Welding

Lozynskyi,

Trembach,

Katinas

et al. 2024

Crystals

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In the conditions of an energy crisis, an important issue is the increase in energy efficiency and productivity of welding and hardfacing processes. The article substantiates the perspective of using exothermic additives introduced into core filler for flux-cored wire arc welding processes as a relatively cheap additional heat source, reducing energy consumption when melting filler materials, and increasing the deposition rate. The mixture design (MD) was selected as the design method to optimize the average values of current and voltage, as well as arc stability parameters depending on core filler composition. This article studies the influence of the introduction of exothermic addition (EA), as well as the ratios CuO/C and CuO/Al on arc stability for the FCAW S process. Parameters characterizing arc stability were determined using an oscillograph, and from the obtained oscillograms, an analysis was conducted on arc voltage and welding current signals during flux-cored arc welding. It was determined that various methods can be used to evaluate arc stability, which can be divided into two groups: graphical (current and voltage cyclograms, box plots with frequency histograms, ellipse parameters plotted on current, and voltage cyclograms) and statistical (standard variation and coefficients of variation for welding current and arc voltage). In this paper, a comprehensive evaluation of arc stability depending on the composition of the cored wire filler was carried out. It was determined that the most stable current parameters were observed for the flux-cored wire electrode with an average exothermic addition content at the level of EA = 26.5–28.58 wt.% and a high carbon content (low values of CuO/C = 3.75). Conversely, the lowest values of arc stability (CV(U) and Std(U)) were observed during hardfacing with a flux-cored wire electrode with a high CuO/Al ratio ≥ 4.5 and a content of exothermic addition in the core filler below the average EA < 29 wt.%. Mathematical models of mean values, standard deviation, coefficient of variation for welding current, and arc voltage were developed. The results indicated that the response surface prediction models had good accuracy and prediction ability. The developed mathematical models showed that the ratio of oxidizing agent to reducing agent in the composition of exothermic addition (CuO/Al) had the greatest influence on the welding current and arc voltage characteristics under investigation. The percentage of exothermic mixture in the core filler (EA) only affected the average welding current (Iaw) and the average arc voltage (Uaw). The graphite content expressed through the CuO/C ratio had a significant impact on welding current parameters as well as the coefficient of variation of arc voltage (CV(U)). Two welding parameters were selected for optimization: the mean welding current (Iaw) and the standard deviation of arc voltage (Std(U)). The best arc stability when using exothermic addition CuO-Al in the core filler was observed at CuO/Al = 3.6–3.9, CuO/C = 3.5–4.26, and at an average EA content of 29–38 wt.%. The significant influence of the CuO/Al and CuO/C ratios on arc voltage parameters can also be explained by their impact on the elemental composition of the welding arc (copper, cupric oxide (CuO), and Al2O3). The more complete this reaction, the higher the amount of easily vaporized copper (Cu) in the arc plasma, enhancing arc stability. The influence of core filler composition on the microstructure of deposited metal of the Fe-Cr-Cu-Ti alloy system was investigated.

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Section: Discussionmentioning

confidence: 99%

Effect of Exothermic Additions in Core Filler on Arc Stability and Microstructure during Self-Shielded, Flux-Cored Arc Welding

Lozynskyi,

Trembach,

Katinas

et al. 2024

Crystals

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“…In Equation (7), T m is given in Kelvin. The values of melting temperature for AISI 1020 steel and ER70S-6 are 1775 and 1538 K, respectively [5].…”

Section: First Approachmentioning

confidence: 99%

“…The values of melting temperature for AISI 1020 steel and ER70S-6 are 1775 and 1538 K, respectively [5]. Taking these values of melting temperatures and inserting them into Equation (7) gives the values of H base and H f iller , which are 10.5 J/m 3 and 7.88 J/m 3 [5], respectively. Figure 2 shows the schematic representation of a cross-sectioned weld bead to illustrate the different parts of the weld cross-section used to calculate melting efficiency experimentally.…”

Section: First Approachmentioning

confidence: 99%

“…Hackenhaar et al [5] reported melting efficiency values for standard GMAW ranging from 0.24 to 0.43 for two different joint configurations (bead-on-plate and T-joint). Recently, Assunção and Bracarense [7] reported values for UW-FCAW ranging from 0.20 to 0.35.…”

Section: Melting Efficiency Saturation Limitmentioning

confidence: 99%

“…Recently, Assunção and Bracarense [7] investigated a strategy to increase melting efficiency in under-water flux-cored arc welding (UW-FCAW). They found that using a dry contact tip caused the melting efficiency increase to approximately, on average, 0.33 compared to conventional UW-FCAW, which presented on average a melting efficiency of 0.25.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Evaluation of Melting Efficiency in Cold Wire Gas Metal Arc Welding Using 1020 Steel as Substrate

Ribeiro,

Assunção,

Gerlich

2024

Metals

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A key welding parameter to quantify in the welding process is the ratio of the heat required to melt the weld metal versus the total energy delivered to the weld, and this is referred to as the melting efficiency. It is generally expected that the productivity of the welding process is linked to this melting efficiency, with more productive processes typically having higher melting efficiency. A comparison is made between the melting efficiency in standard gas metal arc welding (GMAW) and cold wire gas metal arc welding (CW-GMAW) for the three primary transfer modes: short-circuit, globular, and spray regime. CW-GMAW specimens presented higher melting efficiency than GMAW for all transfer modes. Moreover, an increase in plate thickness in the spray transfer regime caused the melting efficiency to increase, contrary to what is expected.

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Study of the hardfacing process using self-shielding flux-cored wire with an exothermic addition with a combined oxidizer of the Al-(CuO/Fe2O3) system

Trembach,

Silchenko,

Balenko

et al. 2024

Int J Adv Manuf Technol

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A novel strategy to improve melting efficiency and arc stability in underwater FCAW via contact tip air chamber

Cited by 6 publications

References 26 publications

Effect of Exothermic Additions in Core Filler on Arc Stability and Microstructure during Self-Shielded, Flux-Cored Arc Welding

Effect of Exothermic Additions in Core Filler on Arc Stability and Microstructure during Self-Shielded, Flux-Cored Arc Welding

Evaluation of Melting Efficiency in Cold Wire Gas Metal Arc Welding Using 1020 Steel as Substrate

Study of the hardfacing process using self-shielding flux-cored wire with an exothermic addition with a combined oxidizer of the Al-(CuO/Fe2O3) system

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