Combined effect of flux and welding parameters on chemical composition and mechanical properties of submerged arc weld metal

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

Fluxes in submerged arc welding of high-strength low-alloy steels are not readily available, flux compositions are not clear and compositions are patented. This study aims at the design, development and optimization of flux for submerged arc welding of high-strength low-alloy steel. Extreme vertices design suggested by McLean and Anderson is used to formulate twenty-one fluxes to study the effect of flux constituents on tensile strength, percentage elongation, impact strength, diffusible hydrogen content and microstructure of the weld metal. Mathematical models for ultimate tensile strength, percentage elongation, impact strength and diffusible hydrogen content for welded specimens versus flux constituents have been developed. From the experiments, it is found that tensile strength and elongation are affected the most with Al2O3 content, whereas CaO and CaF2 contents have significant effect on impact strength. Synergic binary effect of CaO·CaF2, CaO·MgO and Al2O3·CaF2 mixtures is more than other binary mi...

Investigation on flux design for submerged arc welding of high-strength low-alloy steel:

The slag generated during submerged arc welding is thrown away as a waste. Non-biodegradable nature poses problems of storage, disposal, soil pollution and also needs landfill space for dumping. It cannot be used as a filling material in building construction or elsewhere being glassy and brittle material. The non-renewable resources are also getting exhausted fast due to continuous mining for minerals required for manufacturing of fluxes. The successful development of recycling technology that allows the use of slag as a fresh flux will surely overcome the above-mentioned problems and will also prove to be very economical. Slag was processed by replenishing it with suitable alloying elements/deoxidizers by agglomeration. This replenished slag is referred to as recycled slag. Recycled slag in combination with EL-8 filler wire was used in these investigations. The properties of weld metal deposited with recycled slag were investigated. The mechanical properties were satisfactory and satisfied AWS (American Welding Society) requirements. The chemical composition of weld metal was within the acceptance range of AWS specifications. The test plates cleared the radiographic test.

Recycling of slag to act as a flux in submerged arc welding

The prediction model has been developed for low carbon steel weld metal acicular ferrite microstructure as a function of flux ingredients such as CaO, MgO, CaF 2 and Al 2 O 3 in submerged arc welding carried out at fixed welding parameters. The results of quantitative measurements of acicular ferrite (AF) on eighteen no. of weld metal samples were utilised for developing the prediction model. Among the flux ingredients, CaO appears to be most important as an individual as well as interaction with other ingredients in controlling the amount of acicular ferrite content in the weld metal. Furthermore, formation of acicular ferrite is also related to the weld bead geometry which is influenced by flux ingredients. The prediction equation for acicular ferrite has been checked for adequacy by performing separate experiments on welding using randomly designed flux. The'isoresponse curves were developed to show the level of acicular ferrite content at different percentage of flux ingredients.

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Prediction of Acicular Ferrite from Flux Ingredients in Submerged Arc Weld Metal of C-Mn Steel

The transfer of elements across the molten weld pool has been predicted by developing quadratic models in terms of flux ingredients with the application of statistical experiments for mixture design. Bead-on-plate weld deposits were made at fixed welding parameters using submerged are welding fluxes prepared as per extreme vertices algorithm of mixture experiments in a CaO-MgO-Caf 2 -Al 2 O; flux system. The results show that some of the individual flux ingredients and their binary mixtures have a predominant effect on weld metal transfer of oxygen, manganese, silicon, and carbon contents. The analysis of experimental data also indicates that transfer of oxygen is affected by several properties of flux ingredients such as oxygen potential, thermodynamic stahility, and viscosity. In the element transfer of silicon, both thermochemical and electrochemical reaction mechanisms operate simultaneously. Transfer of manganese is principally related to the weld metal oxygen contents as well as electrochemical reaction in the molten weld pool. The transfer of carbon was generally governed by the oxidation reaction. Iso-response contour plots were also developed to quantify the transfer of elements against different flux compositions.

Prediction of element transfer in submerged arc welding

A prediction model has been developed for submerged arc weld-metal chemical composition in terms of flux ingredients with the help of statistical experiments for mixture (extreme vertices design). Bead-on-plate weld deposits as per statistical mixture design experiments were performed at the following welding parameters: current (400 A), voltage (26 V), speed (4.65 mm/s) and electrode extension (30 mm) using CaO-MgO-CaF 2 -Al 2 O 3 flux system. The results show that some of the individual flux ingredients and their binary mixtures have a predominant effect on weld-metal oxygen, manganese, silicon, sulphur, nickel and carbon content. The predicted results show a reasonably good agreement with the experimental results, which were obtained by performing the actual experiments based on a randomly designed flux. Analysis of the experimental data indicate that several mechanisms such as basicity index, oxygen potential, oxide stability, viscosity, electrode chemical reaction, kinetics of slag-metal reaction, etc. are operating simultaneously to yield the final weld-metal composition.

Prediction of submerged arc weld‐metal composition from flux ingredients with the help of statistical design of mixture experiment

Measurement of uncertainties in tensile test properties of Thermo-mechanically Treated (TMT) steel bars

Complete quality control of TMT steel bar and high strength structural steel plates sections and prestressed concrete for total integrity of the final structure

P. Kanjilal

Papers

Combined effect of flux and welding parameters on chemical composition and mechanical properties of submerged arc weld metal

Prediction of element transfer in submerged arc welding

Prediction of submerged arc weld‐metal composition from flux ingredients with the help of statistical design of mixture experiment

Measurement of uncertainties in tensile test properties of Thermo-mechanically Treated (TMT) steel bars

Complete quality control of TMT steel bar and high strength structural steel plates sections and prestressed concrete for total integrity of the final structure