Abstract:The optimization of deposited metal properties through the addition of rare earth elements to welding materials was explored. Utilizing optical microscope, scanning electron microscope, energy dispersive spectroscope, and X-ray diffractometer, combined with software tools like Matlab, Image-Pro Plus, and CHANNEL5, the influence mechanism of rare earth element addition on the strength, toughness, and inclusions of deposited metal in 1000 MPa grade high-strength steel was investigated. The results indicate that the incorporation of rare earth elements enhances the weldability of the welding materials. With the addition of rare earth elements, the tensile strength of the deposited metal increases from 935 MPa to 960 MPa. However, further addition leads to a decrease in tensile strength, while the yield strength continuously increases by 8.5%–17.2%. The addition of appropriate amounts of rare earth elements results in an increase in acicular ferrite and retained austenite content, as well as grain refinement in the deposited metal, leading to 8.5%–24.3% and 15.6%–42.2% enhancement in impact energy at -40 °C and -60 °C, respectively. Additionally, the proper addition of rare earth elements modifies the inclusions and generates fine and dispersed composite inclusions that bond better with the matrix, thereby optimizing the properties of the deposited metal through various mechanisms. Adding an appropriate amount of rare earth elements can significantly enhance the properties of the deposited metal in 1000 MPa grade high-strength steel, and improve the match between high strength and toughness, meeting the demands for high-strength steel used in hydropower applications.