Documenting Ferrite Nucleation Behavior Differences in the Heat-Affected Zones of EH36 Shipbuilding Steels with Mg and Zr Additions

Abstract

The nucleation behavior of ferrites in the heat-affected zones of EH36-Mg and EH36-Zr shipbuilding steels has been documented. Ferrite laths preferred to nucleate on the surface of Al-Mg-Ti-O-Mn-S inclusions in EH36-Mg, but austenite grain boundaries in EH36-Zr, respectively. It is speculated that Al-Mg-Ti-O-Mn-S provides more effective ferrite nucleation sites than Zr-O-Mn-S-Ca-Mg, and a larger driving force is required for the transformation on Zr-O-Mn-S-Ca-Mg. Such differences led to significant variations of the resultant microstructures.