Influence of Hardened Surface on Low Cycle Fatigue Characteristics at Tension-compression and Bending

Abstract

This paper analyses electromechanical hardening of the steel parts surface, when in the contact area so called “white layer” is formed. The experiments were performed to show the influence of “white layer” on strength of the steel C45 specimens under low cycle loading. This paper analyses monotonic and low cycle tension compression and pure bending characteristics of specimens with electromechanically hardened surface. The Performed experiments showed that under monotonic tension strength characteristics (σpr, σ02, σu) are increasing and strain characteristics (eu, ψ) are decreasing. During cyclic stress limited tension compression at low loading levels both the width of plastic strain hysteresis loop and accumulated plastic strain are decreasing, therefore the lifetime is increasing. Under pure bending this tendencies persist, but in this case the lifetime at all loading levels is larger than the lifetime at tension compression.

Keywords

• low cycle fatigue
• pure bending
• electromechanical treatment