Fig. 1. Specimen dimension and test schematic

Fig. 2. Microstructure and grain diameter distribution in different zones of hybrid welded joints. (a) Weld zone; (b) fine grain zone; (c) as-received base metal

Fig. 3. Zn plane-distribution and Mg line-distribution of hybrid welded joint

Fig. 4. Stress-strain curves at room temperature

Fig. 5. S-N curves

Fig. 6. Evolution of fatigue cracks

Fig. 7. Extension paths of fatigue cracks

Fig. 8. Relationship between fatigue crack growth rate and stress intensity factor range for three groups of hybrid welded joints

Fig. 9. Three-dimensional pore distribution of hybrid welded joints

Fig. 10. Fracture morphology of hybrid welded joints. (a) Overall morphology; (b) fracture origin; (c) fatigue striation in crack extension region; (d) rupture region

Fig. 11. Schematic of loading and boundary conditions

Fig. 12. Stress distributions when N is 77300 cycles. (a) Theoretical stress distribution of crack tip[29]; (b) stress distribution around crack tip; (c) stress distribution around crack and pores; (d) stress distribution around crack