Fig. 1. S-130 steel powder. (a) Morphology; (b) particle size distribution

Fig. 2. Flow charts of two heat-treatment processes. (a) Five-step heat treatment; (b) three-step heat treatment

Fig. 3. XRD patterns of SLM as-deposited and heat-treated S-130 samples

Fig. 4. Microstructures of SLM as-deposited S-130 sample on cross and longitudinal sections under different magnifications. (a)(c) Cross section; (d)(f) longitudinal section

Fig. 5. TEM analysis of SLM as-deposited S-130 sample. (a) Bright-field TEM micrograph; (b) corresponding SAED pattern

Fig. 6. Microstructures of two heat-treated S-130 samples on longitudinal sections under different magnifications. (a)(c) Five-step heat treatment; (d)(f) three-step heat treatment

Fig. 7. TEM analysis of heat-treated S-130 sample. (a) Bright-field TEM micrograph; (b) corresponding SAED pattern

Fig. 8. Martensite widths and precipitate sizes of two heat-treated S-130 samples

Fig. 9. Microhardness of SLM as-deposited and heat-treated S-130 samples

Fig. 10. Tensile properties of SLM as-deposited and heat-treated S-130 samples. (a) Tensile stress-strain curves; (b) yield strength, ultimate strength, and elongation

Fig. 11. Fracture morphologies of SLM as-deposited and heat-treated S-130 tensile samples. (a) SLM as-deposited state; (b) five-step heat treatment; (c) three-step heat treatment