Fig. 1. Laser machining system

Fig. 2. Schematic of PA-1Cr18Ni9Ti lap joint

Fig. 3. Schematic of tension-shear test

Fig. 4. Lap joints of PA-1Cr18Ni9Ti (excessive heat input). (a) On PA side; (b) on stainless steel side

Fig. 5. TG-DTG curve of PA

Fig. 6. Schematic of temperature measurement points in interface

Fig. 7. Transient temperature in interface obtained by calculation (laser power is 1100 W, welding speed is 9 mm·s^-1, and defocus is 70 mm)

Fig. 8. Welding thermal cycle curve for interface center(laser power is 700 W, welding speed is 9 mm·s^-1, and defocus is 70 mm)

Fig. 9. Time required for decomposition at different temperatures (α=0.02)

Fig. 10. Thermal decomposition analysis of PA plastics under different welding parameters. (a) Welding speed (laser power is 700 W and defocus is 70 mm); (b) laser power (welding speed is 9 mm·s^-1 and defocus is 70 mm)

Fig. 11. Typical lap joint of PA-1Cr18Ni9Ti

Fig. 12. Cross section of PA-1Cr18Ni9Ti joints obtained at different welding speeds (laser power is 700 W and defocus is 70 mm)

Fig. 13. Interface of PA after tension-shear failure

Fig. 14. XPS analysis of PA-1Cr18Ni9Ti lap joint interface

Fig. 15. Decomposition diagram of O 1s peaks in XPS analysis of PA-1Cr18Ni9Ti lap joint interface