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

The present work is part of a research programme to study the effect of var iation of the coating composition of covered rutile manual electrodes on bo th operational and deposited weld metal properties. According to previous r esults obtained for rutile electrodes, an increase of slag basicity, achiev ed through modifications in the coating, produces an improvement of the imp act properties of the deposited weld metal, as well as a decrease in the di ffusible hydrogen, along with beneficial changes in the operational propert ies 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 electrod e on the operational characteristics of the electrode and the microstructur e, mechanical properties, and diffusible hydrogen content of the electrode weld metal. Tensile strength and Charpy V notch impact properties were meas ured in the all weld metal samples produced using each of, the seven electr odes designed for the present study. A cross-section from each coupon was u sed 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 u sing both direct and alternating current, as well as a decrease in the diff usible hydrogen content in the weld metal. Also, electrodes in which rutile was substituted by sodium oxide in the coating showed an improvement in th e impact properties of the deposit.