Lanthanum-rich difficult-to-deform cobalt-based high temperature alloy plate and preparation method thereof

The invention relates to a lanthanum-rich difficult-to-deform cobalt-based high temperature alloy plate and a preparation method thereof, which relate to the field of metallurgy. The alloy plate is mainly prepared from the following alloy element components in percentage by weight: 0.05 percent to 0.15 percent of C, 19 percent to 24 percent of Cr, 9 percent to 24 percent of Ni, 13 percent to 16 percent of W, less than or equal to 3 percent of Fe, 1 percent to 2 percent of Mn, 0.2 percent to 0.4 percent of Si, less than or equal to 0.04 percent of P, less than or equal to 0.015 percent of S, less than or equal to 0.015 percent of B, 0.03 percent to 0.12 percent of La, and the balance Co. A surface, a dimension and a performance of the alloy plate meet the standard; the alloy plate can be used for manufacturing an aero-engine flame tube; and the preparation method comprises the steps of smelting an alloy raw material by adopting vacuum induction and electroslag remelting smelting processes so as to obtain a ste