Effect of slag variations on ANSI/AWS A5.1–91 E6013 electrode properties: Replacement of TiO₂ in electrode coating with MnO, FeO, CaO, MgO, K₂O, or Na₂O

Abstract

The present work is part of a research programme to study the effect of variation of the coating composition of covered rutile manual electrodes on both operational and deposited weld metal properties. According to previous results obtained for rutile electrodes, an increase of slag basicity, achieved through modifications in the coating, produces an improvement of the impact properties of the deposited weld metal, as well as a decrease in the diffusible hydrogen, along with beneficial changes in the operational properties of the electrode. The aim of the present work is to study the influence of the replacement of titanium oxide with oxides of alkali metals (sodium and potassium), alkaline earth metals (calcium and magnesium), and iron and manganese oxides in the coating of an ANSI/AWS A5.1–91 E6013 type electrode on the operational characteristics of the electrode and the microstructure, mechanical properties, and diffusible hydrogen content of the electrode weld metal. Tensile strength and Charpy V notch impact properties were measured in the all weld metal samples produced using each of the seven electrodes designed for the present study. A cross-section from each coupon was used to determine the chemical composition of the deposit and to carry out a metallographic study using a light microscope. As a result of the addition of different oxides, changes in the operational properties were observed using both direct and alternating current, as well as a decrease in the diffusible hydrogen content in the weld metal. Also, electrodes in which rutile was substituted by sodium oxide in the coating showed an improvement in the impact properties of the deposit.

Valoración del desempeño de un dispositivo de autoalimentación diseñado para la evaluación operativa de electrodos revestidos

“…Los diferentes regímenes de corriente (Tabla 1), conforman los 3 niveles de la variable o factor independiente "Corriente". La literatura especializada [2][3][4][5] reconoce el "tiempo de duración del cortocircuito", como un parámetro importante en la caracterización de los fenómenos de transferencia metálica, obtenido a partir del procesamiento del voltaje y la corriente de soldadura caracterizando en parte el fenómeno de transferencia metálica. La fuente de corriente alterna impone reiteradas inversiones de polaridad en el arco a un ritmo de 120 veces por segundo.…”

“…Algunos sistemas y métodos [2][3][4][5] de estudio de la estabilidad del arco eléctrico con electrodo revestido en el modo de transferencia metálica por cortocircuitos, han sido reportados en artículos de revistas científicas y libros. El uso indiscriminado de estos métodos, puede conducir a distorsiones en los resultados de la caracterización [6], haciéndose interesante retomar el tema de la evaluación de la operatividad eléctrica de los electrodos revestidos.…”

Mixture experiments and their applications in welding flux design

“…Apart from Kanjilal and co-investigators other investigators concentrated on developing models that determine the optimal setting of process factors (Table 1). Development of models should not be limited to process factors because studies have shown that flux formulation plays a prominent role in the productivity of the welding process and the quality of the welded structure (De Rissone et al, 2001;Pessoa et al, 2007;Du Toit, 2007 andDu Plessis et al, 2006). Although factorial design methods provide an efficient means for the optimization of welding process, they do not work well for mixtures of which welding flux formulation is an example (Anderson and Whitcomb, 2002).…”

Weld-metal property optimization from flux ingredients through mixture experiments and mathematical programming approach

“…The quality of weld-metal is often evaluated by many characteristics such as chemical composition, mechanical properties, bead profile and microstructure. Studies have shown that these characteristics are influenced by the welding flux formulation; therefore it is important to select the right type of welding flux ingredients and choose the appropriate proportions of the various flux ingredients to attain a good weld-metal quality [2][3][4][5][6][7][8][9][10] . The conventional approach to welding flux development is by experimental optimization.…”

“…Welding flux design is one of the key areas of arc welding technology that require improvement because the weldmetal quality, productivity of the welding process and economical weld production depend largely on the flux formulation. Operational characteristics such as arc initiation and stability, minimum spatter, positional welding, high deposition rate, penetration and bead morphology are influenced by the welding flux formulation [2][3][4][5][6][7][8] . The quality of weld-metal is often evaluated by many characteristics such as chemical composition, mechanical properties, bead profile and microstructure.…”