Fatigue behavior of thin wires and foils of multi-directionally forged commercial purity grade 2 Ti

Abstract

Thin wires and foils comprising of ultrafine-grained pure titanium (Ti) were made by combined processes of multi-directional forging (MDFing) and either drawing or rolling processes. The MDFed wires and foils exhibited higher tensile strength than the conventional pure Ti wires and plates due to the ultrafine-grained structure. The axial fatigue tests were conducted to investigate their fatigue behavior. The fatigue strengths of conventional pure Ti wires and plates were nearly the same, while the MDFed Ti wires and foils had higher strengths. When the fatigue strengths of MDFed Ti wires and foils were compared, the wires had higher fatigue strength than the foils. EBSD analyses revealed that strong textures were formed in both wires and foils. The basal planes were parallel to the specimen surfaces in wires, while they were inclined against the surface in foils. The texture with the inclined basal planes resulted in the lower crack initiation resistance, resulting in the lower fatigue strength of foils than wires of the MDFed Ti.