The Effect of Multiaxial Forging on the Grain Refinement of Low Alloyed Steel

Abstract

Ultra fine grained low carbon low alloyed steel was formed by multiaxial forging. Altogether five passes of forging were made with decreasing temperature. The first two passes happened in the austenitic state of the steel, the third was made at the austenite-ferrite transition temperature. The fourth occurred in the austenitic-ferritic region, while the last pass was made in pure ferritic state. The intensive plastic deformation caused the austenite-ferrite transition temperature to be lowered, thus the undercooling was larger, and very small ferritic cores were produced. The following deformation made the grain structure even more fine.