Recycling of submerged arc welding slag for sustainability

Abstract

The objective of this paper is to investigate the utilization of Submerged Arc Welding (SAW) slag as a fresh flux for sustainability. Certain alloying elements were added to the crushed slag to adjust the resultant composition of the weld metal as per American Welding Society (AWS) A5.17 and operational characteristics such as arc stability. Here, four distinct controllable variables such as welding speed, arc voltage, welding wire feed rate and nozzle to plate distance were selected as process parameters. A comparative study of the weldments produced with fresh flux, pure slag and recycled slag was done. Characterisation on account of mechanical strength, microstructure, and weld defects shows significant improvement in the weld specimens produced with recycled slag. Results of tensile and impact tests indicated that the weldments made with recycled slag were able to fulfil the AWS requirements. The microstructure analysis gives a clear sign of an almost similar structure of both types of weldments (with fresh flux and reclaimed slag). But the grain boundary between ferrite and pearlite was reduced, and an increment in acicular ferrite was observed in weldment made by recycled slag. The non-destructive test conducted on the weldments produced with recycled slag showed defect-free joints.