2017 Volume 58 Issue 672 Pages 60-65
In this paper, a basic investigation of rotary forging was carried out by experiment and FEM analysis to clarify the mechanism of surface hardening by rotary forging. We used columnar low-carbon steel as a workpiece. As a result, we found rotary forging produces a hard surface because of surface expansion and submicron fine grains. Ratio of minimum principal stress to von Mises stress is less than-1. 2 was proposed as the new criterion for surface on the basis of the result of the minimum principal stress distribution in a hourglass-shaped workpiece. We applied this criterion to a rotor and confirmed that the results correspond with those of FEM analysis.