作为焊接接头组成部分的焊缝金属，其组织与性能直接影响焊接结构的应用及服役寿命。目前，国内外钢铁企业已成功开发出1000 MPa级高强钢，但其配套焊接材料强韧性匹配较差，严重制约了该级别高强钢的推广和应用。本工作采用熔化极气体保护电弧焊(GMAW)方法，制备了三种不同Mo含量的1000 MPa级高强钢焊缝金属。利用SEM、EBSD、TEM以及拉伸、冲击等实验手段研究了1000 MPa级高强钢焊缝金属的微观组织和力学性能，阐明了Mo含量对微观组织演变的影响机制。微观组织分析表明，不同Mo含量焊缝金属组织主要为板条贝氏体(LB)和聚合贝氏体(CB)；随着Mo含量的增加，焊缝金属中大角度晶界占比先下降后上升，焊缝金属组织中贝氏体板条形貌从交织状向平行状转变，CB含量增加。力学性能测试结果表明，随着Mo含量的增加，焊缝金属的淬硬性增加，焊缝金属的屈服强度、抗拉强度和硬度均升高，而冲击韧性先降低后略微升高。冲击断口横截面裂纹分析表明，裂纹易穿过CB，CB的存在明显恶化了焊缝金属的冲击韧性。当Mo含量为0.71%时，焊缝金属强韧性匹配最佳，其屈服强度达(939 ± 10) MPa，抗拉强度达(1181 ± 2) MPa，室温冲击功达(60 ± 3) J。

High-strength steels are essential materials in various sectors, such as engineering machinery, marine engineering, and hydropower. Welding is a crucial thermal processing technique for fabricating structural components made of high-strength steels. The weld metal, as a vital component of the welded joint, plays a pivotal role in determining the applicability and service life of weldments through its microstructural characteristics and properties. At present, steel manufacturers globally have developed 1000 MPa grade high-strength steels. However, the welding consumables associated with these steels exhibit inadequate strength–toughness matching, which significantly hinders their widespread adoption. In this study, weld metals of 1000 MPa grade high-strength steels with three different Mo contents were produced via the gas metal arc welding process. A comprehensive investigation of the microstructure and mechanical properties of weld metals of 1000 MPa grade high-strength steels were conducted using SEM, EBSD, TEM, tensile testing, and Charpy impact testing. The influence mechanism of Mo content on the microstructural evolution was elucidated. The microstructural characterization revealed that the weld metals predominantly comprised lath bainite (LB) and coalesced bainite (CB). As the Mo content was increased, the proportion of high-angle grain boundaries initially decreased and then increased. The morphology of LB transitioned from an interwoven structure to a more parallel arrangement, which was accompanied by an increase in the CB content. Mechanical testing revealed that a higher Mo content enhanced the metal hardenability, resulting in increased yield strength, tensile strength, and hardness. In contrast, the impact toughness initially decreased and then slightly increased. Analysis of the crack propagation paths on the cross-sections beneath the impact fracture surfaces demonstrated that the cracks readily propagated through the CB regions. The presence of CB considerably impaired the impact toughness of the weld metals. The optimal balance between strength and toughness in the weld metals was achieved at 0.71% Mo, resulting in a yield strength of (939 ± 10) MPa, a tensile strength of (1181 ± 2) MPa, and a room-temperature impact energy of (60 ± 3) J.