Fig. 1. DED equipment and heat treatment process. (a) Deposition equipment; (b) heat treatment process

Fig. 2. Residual stress testing sample and equipment. (a) Raw part; (b) residual stress measurement system and testing points

Fig. 3. Fatigue crack propagation specimen and equipment. (a) Dimension of the specimen; (b) INSTRON 8801 tensile testing equipment

Fig. 4. DED deposition finite element model and residual stress test results. (a) Two-layer ten-track model; (b) residual stress testing results

Fig. 5. Finite element model and a-N curves. (a) HS specimen model; (b) a-N curves

Fig. 6. Crack growth area. (a) Virtual crack closure technique^[15]; (b) residual stress testing nodes

Fig. 7. Fatigue crack length and number of cyclic loads. (a) a-N curves; (b) crack initiation and terminal cycle number of the crack

Fig. 8. Instantaneous fracture zone morphology of the three specimens. (a)‒(b) HS specimen; (c)‒(d) LA specimen; (e)‒(f) LSR specimen

Fig. 9. Strain energy release rate and stress intensity factor of CT specimens. (a) Maximum and minimum strain energy release rates; (b) maximum and minimum stress intensity factor

Fig. 10. Effective stress ratio of different CT specimens

Fig. 11. Regression model of the fatigue crack propagation rate. (a) Three-dimensional graph; (b) numerical fitting