Fig. 1. Schematic diagram of laser filler wire welding

Fig. 2. Cross-sections of welded joints. (a) S1 (2.6 kJ/cm); (b) S2 (1.5 kJ/cm); (c) S3 (1.5 kJ/cm, filler wire)

Fig. 3. Microstructures of base metal and weld. (a) Inconel690 base metal; (b) fusion line;(c) center area of weld (enlarged image of P1 in Fig. 2); (d) S1 (enlarged image of P2 in Fig. 2); (e) S2 (enlarged image of P3 in Fig. 2); (f) S3 (enlarged image of P4 in Fig. 2)

Fig. 4. Element line scanning results of welded joints. (a) S2 (1.5 kJ/cm); (b) S3 (1.5 kJ/cm, filler wire)

Fig. 5. Element distribution of weld zone in S2 (1.5 kJ/cm)

Fig. 6. Morphology of white massive particles at different positions in S2 (1.5 kJ/cm). (a) weld zone close to Inconel690; (b) middle zone of weld; (c) weld zone close to SUS304

Fig. 7. Morphology of Cr-rich phase after adding filler wire

Fig. 8. XRD analysis of joint weld for S3 (1.5 kJ/cm, filler wire)

Fig. 9. Microhardness of joints with different parameters

Fig. 10. Tensile strength and elongation of joints with different parameters

Fig. 11. Tensile fracture morphology under different welding parameters. (a) Laser welding with high heat input;(b) laser filler wire welding with low heat input