Microstructure and Properties of 22MnB5/DP980 Laser Tailored Blank after Hot Stamping

The 1.6mm thick 22MnB5 hot-formed steel sheet and DP980 dual-phase steel sheet were laser tailor-welded,and then the hot-forming quenching test of the tailor-welded plate was conducted. The microstructure and properties of the tailor-welded plate before and after quenching were studied. The results show that the microstructures of different areas of the welded joint before quenching are transformed into lath martensite after quenching; the average tensile strength of the welded joint after quenching is 1294 MPa, which is 97% higher than that before quenching; in addition, compared with that of the 22MnB5 whole hot-formed steel plate after quenching, its strength plasticity product is increased by 23%. The hardness of the welded joint before quenching is distributed in the shape of " 几 ". The peak value of the hardness distribution is located in the weld zone. The heat affected zone at 22MnB5 side has hardened zone, the heat affected zone at DP980 side has softened zone. After quenching, the hardness distribution of the welded joint tends to be flat, and the hardness firstly increases then decreases from the 22MnB5 base material area to the DP980 base material area. The tempering softening area on the DP980 side and the hardening area on the 22MnB5 side disappear. The average hardness of the welded joint is 60% higher than that before quenching. The hardness of the 22MnB5 base metal zone is 330% higher than that before quenching.