Fig. 1. Microstructure of base material observed by (a) optical microscope and (b) field emission scanning electron microscope

Fig. 2. Schematic of experimental setup for laser welding

Fig. 3. Dimension of standard tensile sample

Fig. 4. Effect of line energy on widths of different areas of laser welded joint

Fig. 5. Regional distribution of 3# welding seam and right HAZ. (a) Weld profile; (b) CG-FGZ; (c) FG-ICZ

Fig. 6. Effect of line energy on mechanical properties and formability of joint. (a) Mechanical properties and formability of joints with different line energies; (b) power and weld speed combined effect of the process window

Fig. 7. Laser welded joints under different line energies. (a) Microhardness distribution; (b) average hardness in each region

Fig. 8. (a) Fracture location of joint; (b) force analysis of SZ