Fig. 3. Microstructural analysis of 3D-printed 1040 steels.

a X-ray diffraction (XRD) spectra. b–d Longitudinal electron backscattered diffraction inverse pole figure (EBSD-IPF) maps of samples fabricated with energy inputs of (b) 69 J/mm³, (c) 93 J/mm³, and (d) 127 J/mm³. e−g The corresponding Grain Average Band Contrast maps, retrieved from (b−d), respectively. The color scales represent the band contrast (BC) values. h Bright-field transmission electron microscopy (TEM) micrograph of the low-energy-produced sample, with the label M representing martensitic α’-laths. Magnified views of the marked areas in (h), showing typical (i) bainite α’-laths and (l) martensite α’-laths. The yellowish dashed lines in (i) indicates lath boundaries. j, m The diffractions patterns of (i) and (l), respectively, taken along the ${\left[011\right]}_{{\alpha }^{\prime }}$ axes. k, n Dark-field TEM images taken from the diffraction spot marked in (j) and (m), respectively. The arrows marked in (k) shows ω’-Fe₃C nanoparticles. Source data are provided as a Source Data file.