Fig. 1. Microstructures of DP steels with different martensite contents. (a) 800 MPa; (b) 1000 MPa

Fig. 2. Schematic of tailored blank laser welding

Fig. 3. Size of tensile sample

Fig. 4. Microstructures of DP steel joints with different martensite contents. (a) 800 MPa; (b) 1000 MPa

Fig. 5. Microstructure of 800 MPa welded DP steel joint. (a) FZ; (b) CGHAZ; (c) FGHAZ

Fig. 6. Microstructures of non-full transformation areas of DP steel joints with different martensite contents. (a) 800 MPa, MGHAZ; (b) 1000 MPa, MGHAZ; (c) 800 MPa, TZ; (d) 1000 MPa, TZ

Fig. 7. Microhardness distributions of welded joints, width decrease and maximum microhardness decrease of non-full transformation area. (a) 800 MPa, microhardness distribution; (b) 1000 MPa, microhardness distribution; (c) width decrease of non-full transformation area; (d) maximum microhardness decrease of non-full transformation area

Fig. 8. Engineering stress-strain curves of DP steel joints with different martensite contents and BMs

Fig. 9. Macro-morphologies of tensile samples of DP steel joints with different martensite contents

Fig. 10. Microstructural diagram of welded DP steel joints

Fig. 11. Erichson value of DP steel joints with different martensite contents and BMs

Fig. 12. Erichson fracture morphologies of DP steel joints with different martensite contents. (a) 800 MPa; (b) 1000 MPa

Table 1. Chemical composition of DP steels with different martensite contents (mass fraction,%)

Table 2. Mechanical properties of DP steels with different martensite contents

Table 3. Elongation of DP steel joints with different martensite contents