Study on undercooling of dendrite tip during electron beam treatment

The surface of 5CrNiMo steel was treated using electron beam, and the sample's cross-section was separated into three layers: re-melting layer, heat affected layer, and substrate. The re-melting layer's microstructure is primarily made up of ultrafine dendrites. The undercooling of dendritic tip during rapid solidification was calculated using BCT dendrite growth theory. According to the calculations, the overall undercooling of dendritic tip is 344.8 K, of which kinetic undercooling is 259.5 K. The results presented above demonstrate our study can provide methodological reference for the calculation of undercooling during electron beam treatment. [Display omitted] •The surface of 5CrNiMo steel was modified using electron beam.•The re-melting layer is primarily made up of ultrafine dendrites.•The undercooling was calculated using BCT dendrite growth theory.•The overall undercooling of dendritic tip is 344.8 K.