Development of a micro-scale Y–Zr–O oxide-dispersion-strengthened steel fabricated via vacuum induction melting and electro-slag remelting

In this paper, the CLAM steel strengthened by micro-scale Y–Zr–O was prepared by vacuum induction melting followed by electroslag remelting (VIM-ESR). Yttrium (Y) and zirconium (Zr) were easy to aggregates into massive yttrium-zirconium-rich inclusions in the steel melted by vacuum induction melting (VIM), which would interrupt the continuity of the matrix and reduce the mechanical properties of steel. Micron-sized Y–Zr–O inclusions would be produced with the removal of original blocky Y–Zr-rich inclusions and the submicron-sized inclusions smaller than 0.2 μm could be retained in the steel. The small grain size and the better refinement and distribution uniformity of Y–Zr–O inclusions after remelting would be responsible for the better yield strength and toughness. For VIM-ESR alloy, the ultimate tensile strength is 749 MPa and the yield strength is 642 MPa at room temperature, meanwhile they are 391 MPa and 367 MPa at 600 °C, respectively. Meanwhile, the ductile-brittle transition temperature (DBTT) reduced from −43 °C (VIM) to-76 °C (VIM-ESR). Keywords: CLAM, Electroslag remelting, Y–Zr–O inclusions, Tensile mechanical, DBTT