Mechanism and optimization of activating fluxes for process stability and weldability of hybrid laser-arc welded HSLA steel

Zhang, Shiwei; Wang, Yadong; Xiong, Zhenhua; Zhu, Min; Zhang, Zhijie; Li, Zhuguo

doi:10.1007/s40194-020-01038-3

Cited by 4 publications

(5 citation statements)

References 30 publications

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“…In addition, the presence of Al + Fe 2 O 3 powder had low ionization, thereby improving the arc stability. Research by Zhang et al [107] also reported a reduction in the welding voltage and an increased welding current when introducing Fe 2 O 3 into filler materials. This explains that the decomposition and evaporation of the filler materials produced oxygen, which led to a narrowing of the arc [107].…”

Section: Discussionmentioning

confidence: 94%

“…When metal vapor enters the arc column, the distribution of the current density and the energy transmitted to the workpiece changes [104,105]. The vapor additives cause the changes, and in turn, affect the energy transport as well as temperature and velocity distributions in the arc column [106,107]. Thus, research by Jia et al [108] has shown that during the FCAW-SS process in the arc column, it is possible to detect in addition to the compounds providing gas protection (mainly CO and CO 2 as well as F 2 and F) and gases inevitably coming from the surrounding atmosphere (O 2 , H, N, and N 2 ), also ions or molecules of most of the core filler components such as Mg, Si, K, Ca, Ti, Cr, Mn, Fe, and Ni.…”

Section: Discussionmentioning

confidence: 99%

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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: 94%

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

View full text Add to dashboard Cite

show abstract

“…In addition, the presence of Al + Fe2O3 powder has low ionisation, thereby improving the arc stability. Research by Zhang et al [62] also reported a reduction the welding voltage and an increased welding current when introducing Fe2O3 into filler materials. This explains that the decomposition and evaporation of the filler materials produced oxygen, which led to a narrowing of the arc [62].…”

Section: Discusionmentioning

confidence: 94%

“…When metal vapor enters the arc colum, the distribution of the current density and the energy transmitted to the workpiece will be changed [59,60]. The vapor additives causes the changes, in turn, affect the energy transport as well as temperature and velocity distributions in the arc colum [61,62]. Thus researches by Jia et al [63] have shown that during FCAW-S process in the arc column it is possible to detect in addition to the compounds providing gas protection (mainly CO and CO2 as well as F2.…”

Section: Discusionmentioning

confidence: 99%

Investigation of the arc stability during self-shielded flux-coed arc welding with exothermic additions

Trembach,

Silchenko,

Sukov

et al. 2023

Preprint

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In the conditions of energy crisis an important issue is the increase of energy efficiency and productivity of welding and hadfacing process. The article substantiates the perspective of using exothermic additives introduced into core filler for flux cored wire arc welding process, as a relatively cheap additional heat source, reducing energy consumption for melting of filler materials, and increasing the deposited rate. This article studies the influence of the introduction of the exothermic addition (EA), as well as the ratio (CuO/C) and CuO/Al on arc stability for the FCAW S process. 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. Mathematical models of mean values, standard deviation, coefficient of variation for welding current and arc voltage were developed.

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“…They discovered that sulfur reduced the corrosion resistance of the welding joint to an extent, but it increased molten pool fluidity, promoted heat transmission, and extended the welding depth. The addition of SiO 2 , TiO 2 , ZnO, and Fe 2 O 3 improved weld formation, extended the penetration depth, and increased the laser absorptivity of materials in hybrid laser-arc-welded HSLA steel [25]. Experimental studies of surface-active element on welding joints have mainly focused on the influences on morphology and mechanical properties, and the fluid flow and heat transfer of the molten pool needed to be further studied.…”

Section: Introductionmentioning

confidence: 99%

Effect of Surface-Active Element Oxygen on Heat and Mass Transfer in Laser Welding of Dissimilar Metals: Numerical and Experimental Study

Dong

et al. 2022

Metals

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The effects of the surface-active element oxygen on the laser welding of 304 stainless steel (304SS) and nickel were numerically and experimentally studied in pure argon and argon–oxygen mixed gas atmospheres containing 21% oxygen (AMO). In this study, the molten pool morphology, thermal behavior, solidification phenomenon, correlation between dilution and convection flow, and microhardness of welding joints were analyzed. As a result of oxygen effects, the molten pool was deeper, the maximum temperature was higher, and the maximum flow velocity was lower in the AMO. The cooling rate (GR) and combination parameter (G/R) were studied by the direct simulation of temperature gradient (G) and solidification growth rate (R). Combined with the solidification microstructure, it was found that oxygen had little effect on grain size. The major elements Fe, Cr, and Ni within the solidified molten pool in the AMO were uniformly diluted, while the distribution of the above elements was non-homogenous in pure argon. Stronger flow and multiple directions of convection inside the molten pool contributed to uniform dilution in the AMO. The distribution of microhardness was similar to the content of Cr, and the microhardness at the substrate interface of the joint was higher in the AMO than in pure argon. The preliminary conclusions of this study provide in-depth insights into the effects of surface-active element oxygen on heat and mass transfer in laser dissimilar welding.

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Mechanism and optimization of activating fluxes for process stability and weldability of hybrid laser-arc welded HSLA steel

Cited by 4 publications

References 30 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

Investigation of the arc stability during self-shielded flux-coed arc welding with exothermic additions

Effect of Surface-Active Element Oxygen on Heat and Mass Transfer in Laser Welding of Dissimilar Metals: Numerical and Experimental Study

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