ELEMENT TRANSFER BEHAVIOUR OF RECYCLED SLAG IN SUBMERGED ARC WELDING

Abstract

Submerged Arc Welding is a versatile metal joining process in industry. It is the most economical process these days since it involves the concept of “Zero Waste” or “Waste to Wealth”. In this present work, an attempt has been made to analyse the effect of Welding parameters on C, Mn, Si, S and P content of the weld metal by using recycled slag. Slag has been recycled by mixing various percentage of crushed slag with fresh flux. Using this slag flux mixture, the weld metal chemistry of the given welded specimens were evaluated and compared. As a result it was found that slag flux mixture upto 75% slag is within the acceptable range of AWS (American Welding Society) specifications. The design matrix was formulated on the basis of Half Factorial design. Welding Current, Arc Voltage and Travel Speed were selected as three independently controllable process parameters. Welding was carried out on mild steel plate to obtain bead on plate welds. The coefficients of models were determined by Regression Analysis. The adequacy and the significance of the model was tested by ANOVA technique followed by ‘F’ test and ‘t’ test respectively. Using this model, main and interaction effects of the process parameters on responses – C, Mn, Si, S and P were determined quantitatively and presented graphically. As a result ,it has been found that the transfer of the elements have predominant effect on the welded specimen even when the process involves the use of reclaimed slag .Therefore, it is necessary to compute and understand the effect of various factors which controls the weld metal chemistry.