Oxide metallurgy technology plays an important role in inclusion control and is also applied to improve the weldability of high strength steel. Based on the requirements of the weldability in high strength steel, the influencing factors of weld heat affected zone (HAZ) as well as the development and application status of oxide metallurgy technology are summarized in this review. Moreover, the advantages and difficulties in the application of rare earth (RE) oxide metallurgy technology are analyzed, combined with the performance mechanism of RE and its formation characteristics of fine and high melting point RE inclusions with distribution dispersed in liquid steel. With the weldability diversities of different high strength steels, the research status of weldability of high strength steel with high carbon equivalent and the effects of RE on the microstructure and properties of HAZ are discussed, and some suggestions about further research in the future are proposed.

The microstructure and carbides evolution of high-speed steel after electroslag remelting and solution treatment were studied. The thermodynamic precipitation mechanism of carbides in solid phase was discussed and the characteristic parameters of carbides in different processes were also investigated. The results show that there were large lamellar and fibrous Mo₂C and a small amount of VC in the ESR ingot. Mo₂C are metastable carbides, which can be decomposed into VC and Fe₂Mo₄C during the solution treatment. The average diameter of the carbides is reduced to 1.28 μm and the space distance is reduced to 3.23 μm after forging and hot rolling, which means carbides are completely spheroidal and dispersed in matrix.