Investigation of TiO2–SiO2–CaO–CaF2 based electrode coatings on weld metal chemistry and mechanical behaviour of bimetallic welds

Proceedings of the Institution of Mechanical Engineers, Part E:

2018

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Submerged arc welding is widely used in pipeline manufacturing due to higher efficiency as compared to the other welding processes. In present study, TiO2-SiO2-CaO and SiO2-CaO-Al2O3–based submerged arc welding fluxes were developed for joining of linepipe steel. Twenty-one fluxes were formulated based on mixture design methodology. Fluxes were analysed using X-ray florescence (XRF), thermogravimetric, differential-scanning calorimetry, Hot-disc and X-ray diffraction (XRD) techniques. The structural behaviour of rutile basic fluxes were analysed using Fourier transformed infrared spectroscopy (FTIR). Thermo-gravimetric analysis and differential scanning calorimetry were performed from 25 ℃ to 900 ℃ in order to determine the thermal stability and change in enthalpy of fluxes. Thermal conductivity, thermal diffusivity and specific heat of each flux were evaluated by hot disc technique. The density and grain fineness number for flux particles was evaluated at room temperature. Multi objective optimisation was performed to derive the optimised flux formulations. Individual effect of all the mixture constituents is rarely observed on the physicochemical properties of fluxes as compared to the binary and ternary mixture effects. The binary compositions significantly affect the density. TiO2-CaO is the most effective binary mixture which has increasing effect on density while all remaining binary mixture constituents have decreasing effect. The weight loss of fluxes observed during thermogravimetric analysis is affected by binary and ternary mixture constituents. Both binary and ternary flux mixtures affect change in enthalpy observed during differential scanning calorimetry. SiO2.Al2O3 is the only most effective binary mixture constituent of flux having increasing effect on thermal conductivity. Binary mixture constituents TiO2.CaF2, SiO2.Al2O3 and CaO.Al2O3 are the most effective and having synergistic effect on thermal diffusivity.

Section: Results and Development Of Regression Model For Physico-chemmentioning

confidence: 99%

Section: Experimental Designmentioning

confidence: 99%

Section: Experimental Designmentioning

confidence: 99%

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Design and development of submerged arc welding fluxes using TiO₂-SiO₂-CaO and SiO₂-CaO-Al₂O₃ flux system

Sharma

Proceedings of the Institution of Mechanical Engineers, Part E:

2018

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“…The coating formulations of welding electrodes were designed using extreme vertices design as suggested by McLean and Anderson. 16 The method suggests that constrained mixture design for a mixture of k ingredients having both lower and upper bounds on some or all of ingredients may be represented mathematically as follows 17,18 04 i 4x i 4 i 4100 ð1Þ and…”

Section: Design Of Experimentsmentioning

confidence: 99%

Investigations on weld metal chemistry and mechanical behaviour of bimetallic welds using CaO–CaF₂–SiO₂–Ni based electrode coatings

Bhandari¹,

Proceedings of the Institution of Mechanical Engineers, Part L:

Arora

et al. 2016

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The bimetallic welds between ferritic low alloy steels and austenitic stainless steels are widely used in the heat piping transport systems of nuclear power plants for connecting the heavy section low alloy steel components with those of high temperature stainless steel pipes. The operating experience of major nuclear power plant components has recently shown that bimetallic joints can jeopardize the plant availability and safety because of increased incidences of failure. In shielded metal arc welding process, the occurrence and severity of weld defects mainly depend upon the type of electrode filler wire and the electrode coating ingredients used. The use of nickel based filler metals is no longer considered as the final solution for unexpected failures of bimetallic welds due to incidences of hot cracking. In the present paper, an attempt has been made to design and develop an intermediate electrode based on CaO–CaF2–SiO2 ternary phase diagram system and nickel as an additional electrode coating ingredient using mild steel as a filler wire for the bimetallic weld joint. The extreme vertices methodology has been used to design 21 electrode coating formulations. The quadratic regression models for weld metal chemistry, ultimate tensile strength, impact toughness, macrohardness, diffusible hydrogen content, and corrosion rate in terms of electrode coating ingredients, have been developed and checked for adequacy using analysis of variance. The work aims at studying the individual as well as combined effect of electrode coating ingredients on the measured weld responses and microstructures of the weld. Also, the electrode coating formulations suggesting multiobjective optimized solutions have been proposed.

“…Significant work is reported on studying the effect of binary and tertiary interactions on the physicochemical properties of fluxes, weld metal chemistry, and mechanical properties of the weld. [18][19][20][21][22][23][24][25] Correlation between the structural aspect of flux and its wettability behavior is still unexplored.…”

Section: Introductionmentioning

confidence: 99%

High-temperature wettability study of mineral waste added CaO–CaF₂–SiO₂ and CaO–TiO₂–SiO₂-based electrode coating for offshore welds

Khan

Kumar

Proceedings of the Institution of Mechanical Engineers, Part L:

2020

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This paper investigates the high-temperature wettability property of the mineral waste red ochre added CaO–CaF2–SiO2 and CaO–TiO2–SiO2-based electrode coating mixture for offshore welding. The extreme vertices design method was applied to formulate 21 coating compositions. The pellets made from developed electrode coating compositions were exposed to a high temperature of 1250℃ on the substrate of super duplex stainless steel of 2507 grade. The molten flux has been characterized for contact angle, surface tension, adhesion energy and spreadability. The regression analysis has been used to estimate the effect of individual components and their interactions on the wettability property parameters. The developed regression models have been optimized using multiresponse optimization to achieve optimum flux composition. Structural analysis of flux mixture has been done using X-ray diffraction and Fourier transformation spectroscopy.