Fig. 1 a Secondary electron image of powders used for the SLM process in this study, b powder size distribution (including D10, D50 and D90) of the raw powders

Fig. 2 Schematic drawing of the tensile testing sample used in this study

Fig. 3 Brinell hardness (with standard deviation as the error bars) of the as-fabricated and heat-treated samples in both longitudinal and transverse directions, and the wrought AISI420

Fig. 4 a Representative tensile stress-strain curves of SLMed AISI420 in the two directions and wrought AISI420, b calculated tensile properties, which include 0.2% proof stress, ultimate tensile stress and total elongation, of AISI420 and wrought AISI420

Fig. 5 Optical micrograph of as-fabricated sample taken in the longitudinal direction

Fig. 6 Backscattered electron micrographs of as-fabricated samples taken at a longitudinal, b transverse directions, and phase maps with the area fractions of martensite and calculated from EBSD datasets of as-fabricated samples c longitudinal, d transverse directions

Fig. 7 Inverse pole figure orientation maps of martensitic phase on a longitudinal direction, b transverse direction of as-fabricated samples, with the black background austenitic phase, and inverse pole figure orientation maps of austenitic phase on c longitudinal direction, d transverse direction, with the black background martensitic phase

Fig. 8 Pole figures of a martensite, b austenite with their texture indexes in the longitudinal direction of the as-fabricated samples, with the building direction (Z) marked next to the pole figures

Fig. 9 IPF OMs of a, e martensitic phases, b, f austenitic phases in the two selected parent-austenitic grains, and the corresponding pole figures of c, g martensitic phases, d, h austenitic phases

Fig. 10 Backscattered electron images of heat-treated SLMed AISI420 taken at a longitudinal, b transverse directions; and phase maps with the area fractions of martensite and calculated from EBSD datasets of as-fabricated samples c longitudinal, d transverse directions

Fig. 11 IPF OMs of heat-treated SLMed AISI420 on a longitudinal, b transverse directions, and their corresponding pole figures on c longitudinal, d transverse directions with the texture indexes labelled

Fig. 12 a Grain size distribution, b grain orientation spread of austenitic grains in the as-fabricated sample and martensitic grains in both as-fabricated and heat-treated samples. Only the calculated results on longitudinal direction, which were also representative of those on transverse direction, were plotted