Staggered Anvil and Rotation Processes for Refining and Homogenizing Centimeter-Scale Grains during FM Forging of Superheavy Ingots

Abstract

Typically, the microstructure of superheavy ingots weighing more than 300 tons consists of centimeter-scale grains. In this study, a forging method for refining and homogenizing such grain structure is proposed on the basis of modeling and simulation results. After a superheavy ingot has been subjected to a single deformation process during FM forging, different areas of the ingot exhibit variations in the degree of deformation and microstructure. The critical value of the equivalent strain for obtaining a fine-grained structure (∼30 µm) was calculated to be 0.16; on the basis of this, the staggered anvil process was designed in order to improve the deformation uniformity in the meridian plane of heavy forgings. Given that traditional rotation processes usually result in inhomogeneous deformation distributions in the cross-sections of heavy forgings, the quantitative relationship between the rotation angle and the reduction ratio was determined. This was done with the view of improving the rotation process to solve the problem of uneven deformation distribution close to the surfaces of heavy forgings. Using the improved rotation process should ensure a uniform microstructure across the entire cross-section.