Fig. 1. Morphology and particle size distribution of 24CrNiMo powder. (a) Morphology; (b) particle size distribution

Fig. 2. Schematics of scanning strategies. (a) 0° linear scanning; (b) 45° rotating scanning; (c) 90° rotating scanning; (d) 67° rotating scanning

Fig. 3. Schematics of thermal fatigue test equipment

Fig. 4. Size of thermal fatigue test specimen

Fig. 5. OM morphologies of 24CrNiMo alloy steel formed by selective laser melting (SLM) under different scanning strategies. (a) 0° linear scanning; (b) 45° rotating scanning; (c) 90° rotating scanning; (d) 67° rotating scanning

Fig. 6. Microstructures of 24CrNiMo alloy steel formed by SLM under 0° linear scanning strategy. (a) Molten pool; (b) inside of the molten pool; (c) remelting zone

Fig. 7. IPF images of 24CrNiMo alloy steel formed by SLM. (a) X-Y section, 0° linear scanning; (b) X-Y section, 67° rotating scanning; (c) Y-Z section, 0° linear scanning; (d) Y-Z section, 67° rotating scanning

Fig. 8. XRD patterns of 24CrNiMo alloy steel formed by SLM under different scanning strategies

Fig. 9. Oxidation phenomenon during thermal fatigue. (a) Macroscopic features comparison of the sample before and after thermal fatigue test; (b) oxidation morphology

Fig. 10. Kinetic curves of thermal fatigue crack propagation of thermal fatigue specimens under different scanning strategies

Fig. 11. Morphologies of thermal fatigue crack propagation of specimens formed with different scanning strategies. (a) 0° linear scanning (laser scanning path is parallel to the notch direction); (b) 45° rotating scanning; (c) 90° rotating scanning; (d) 67° rotating scanning; (e) 0° linear scanning (laser scanning path is perpendicular to the notch direction)

Fig. 12. Typical morphologies of thermal fatigue crack propagation. (a) 0° linear scanning; (b) 67° rotating scanning

Fig. 13. Grain boundary misorientation distributions. (a) X-Y section, 0° linear scanning; (b) X-Y section, 67° rotating scanning

Fig. 14. Morphologies of thermal fatigue crack. (a) Oxidation corrosion; (b) independent growth crack; (c) crack tip