Fig. 1. Principle of inside-laser powder feeding

Fig. 2. Forming part model. (a) Global shape; (b) face 1; (c) face 2; (d) subface arc

Fig. 3. Slicing method of formed structure. (a) Extract center line; (b) normal section; (c) dissociation along length; (d) curve splice units

Fig. 4. Location of each side in the coordinate system. (a) Face 1 and face 2; (b) bottom surface arc

Fig. 5. Representation of direction vector in base coordinate system. (a) Direction angle; (b) projection vector

Fig. 6. Trajectory planning of deposition parts. (a) Discrete unit location; (b) coordinate transformation process

Fig. 7. Deposition process. (a) Horizontal slice; (b) nozzle tilt angle of 4.3°; (c) nozzle tilt angle of 44.6°; (d) nozzle tilt angle of 88.13°

Fig. 8. Sample dimension. (a) Total height; (b) section thickness; (c) central angle of face 2; (d) central angle of subface

Fig. 9. Microhardness measurement. (a) Sampling regions; (b) microhardness at different locations

Fig. 10. Tensile fracture morphology under different magnifications. (a) 1000×; (b) 2000×; (c) 5000×

Fig. 11. 3D topography of the surfaces on both sides of each region A and B. (a) A side of region 1; (b) A side of region 2; (c) A side of region 3; (d) A side of region 4; (e)B side of region 1; (f) B side of region 2;(g) B side of region 3; (h) B side of region 4

Fig. 12. Microstructures at different regions. (a) Region 1; (b) region 2; (c) region 3; (d) region 4