Formation and evolution of craters in carbon steels during low-energy high-current pulsed electron-beam treatment
Optical micrographs of the untreated (a) 45#, (b) T8, and (c) T10 steel samples.
Optical micrographs taken on the LEHCPEB-treated T8 samples with (a) 5, (b) 10, and (c) 25 pulses.
Typical surface micrographs of the LEHCPEB-treated T8 steel samples: (a) OM, 5 pulses, (b) SEM, 5 pulses, (c) OM, 25 pulses, and (d) SEM, 25 pulses.
Evolution of crater density with the number of pulses on the LEHCPEB-treated carbon steels.
Crater size distributions of the LEHCPEB-treated T8 samples with (a) 5, (b) 10, and (c) 25, pulses.
Laser three-dimensional images taken on the surface of T8 samples treated by LEHCPEB with (a) 5 and (b) 25 pulses.
Evolution of surface roughness vs number of pulses for 45#, T8, and T10 steel samples.
Typical optical cross-sectional micrographs of the treated samples (etched in 4% alcohol solution): (a) 45#-1, (b) 45#-3, and (c) T8-1. The melted layer is “white” because it is weakly etchable (Ref. 6 ) and the heat-affected zone shows a dark color.
Measured melted layer depth of the three kinds of steel under different LEHCPEB numbers of pulses.
Calculated temperature profile (a) and melting procedure [(b) and (c)] of 45# sample treated by LEHCPEB with one pulse, energy density being about .
Schematic illustration of (a) formation of a pool of melt in the subsurface layer and (b) eruption, formation of a crater and removal of the melted layer. (c) Cross-sectional OM image of the 45# sample after ten pulses, showing the funnel-like crater morphology.
Schematic illustration of melted layer depth and electron-beam energy deposition in steels when the melted layer is thin (a) and when the melted layer is thick (b).
LEHCPEB treatment parameters for the three kinds of carbon steels.
Evolution of values vs number of pulses for all the treated samples.
Evolution of average crater depth vs number of pulses for all the treated samples.
Evolution of melted layer depth vs number of pulses for all the treated samples.
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