对1.2 mm厚DP780双相钢和1.0 mm厚HC660双相钢进行了CO₂激光对接焊，研究了该异质焊接接头的显微组织和力学性能。结果表明：焊接接头焊缝区组织由粗大板条马氏体和少量铁素体组成，热影响区组织不均匀，分为粗晶区、细晶区和临界区；显微硬度以焊缝为中心呈不对称分布，焊缝区、热影响区和母材的平均显微硬度依次降低，热影响区出现软化现象；焊接接头的抗拉强度和HC660双相钢的相近，伸长率则降低至7.8%，断裂发生在热影响区附近的HC660双相钢处，断裂方式为韧性断裂。

1.2 mm thick DP780 dual-phase steel and 1.0 mm thick HC660 dual-phase steel were butt welded by CO₂-laser welding. The microstructure and mechanical properties of the dissimilar joint were studied. The results show that the microstructure of weld zone in the welded joint consisted of coarse lath martensite and a little ferrite. The microstructure of heat affected zone was uneven and could be divided into coarse grained zone, fine grained zone and intercritical zone. The microhardness of the welded joint was asymmetrically distributed around the weld zone center. The average microhardness of the weld zone, heat affected zone and base metal decreased successively. A softening phenomenon was observed in the heat affected zone. The tensile strength of the welded joint was close to that of the HC660 dual-phase steel, while the elongation was reduced to 7.8%. Fracture occurred in HC660 dual-phase steel near heat affected zone. The fracture mode was ductile fracture.