Unravelling microstructure evolution induced mechanical responses in weld metals of EH420 shipbuilding steel subjected to varied high heat inputs

Microstructure evolution roadmap and pertinent mechanical responses in weld metals subjected to various heat inputs have been profiled in EH420 shipbuilding steel by scanning electron microscopy, energy dispersive spectrometry, electron backscatter diffraction and mechanical testing. As the heat input increases from 11.5 to 20 kJ mm –1 , relative percentage of acicular ferrites decreases from 62.2 to 41.3%, while that of grain boundary ferrites increases from 10.4 to 30.2%, which are enabled by the diminished number of potent nuclei at lower cooling rate, and largely responsible for the reduced hardness and toughness.