Why should the steel ingot be uniformly annealed in the production of flange forgings?

    Ingots (steel ingots) are often used in the production of flange forgings. The homogenization annealing of steel ingots is to heat the ingots with complex chemical composition, fast non-equilibrium crystallization and poor plasticity to a temperature close to the melting point for a long time to keep the alloy atoms. Fully diffuse to eliminate chemical composition and tissue inhomogeneity, and improve the plastic deformation ability of steel ingots when manufacturing flange forgings. This type of annealing is characterized by changes in organization and properties that are irreversible and can only shift to equilibrium. The ingot homogenization annealing is to achieve homogenization by the dissolution of the phase and the diffusion of atoms under the heating condition of the ingot, which plays an important role in the future processing of flange forgings.

    In the process of homogenization annealing of steel ingots, in addition to the diffusion of atoms in the crystal, it is accompanied by changes in the structure. The major structural changes in homogenization annealing are dendrite segregation elimination and non-equilibrium phase dissolution. It is maintained at a high temperature for a long time, and the atoms are fully diffused to eliminate dendrite segregation to achieve uniform composition. For alloys that are still single-phase in a non-equilibrium state, the main process that occurs during homogenization annealing is the homogenization of the solid solution grains. When there is a non-equilibrium metastable phase in the alloy, both of the above main processes occur. In addition, during the homogenization annealing process, it is often accompanied by decomposition of supersaturated solid solution, insoluble excess phase aggregation and spheroidization, grain growth, phase transition, and quenching effect which may occur due to excessively fast cooling.