Copyright © by The International Society of Offshore and Polar Engineers A Microstructural Study of Friction Stir Welded Joints of Carbon Steels

Friction Stir Welding (FSW) is an emerging technology that has made significant inroads in the joining of aluminum alloys in the aerospace industry. To explore the potential advantages in joining carbon steels by FSW, the present study focuses on microstructure characterization of friction stir welded API grade X80 and L80 steels using SEM, TEM and SIMS. The study focuses on the mechanisms of microstructure evolution at various regions of the FSW joint, resulting from the effect of strain, temperature and tool interaction on the phase transformations. A qualitative comparison of the microstructural features between friction stir welds and typical fusion welds in these steels is also presented