Effect of Heat Treatment on Fatigue Properties of TA15 Titanium Alloy Repaired by Laser Deposition

Abstract

Laser deposition repair technology is employed to repair damaged TA15 titanium alloy forgings. Heat treatment is used to control the microstructure, strength, and plasticity of these repaired forgings. The fatigue properties and crack initiation and propagation characteristics of the repaired parts are studied. Optical microscopy and electron microscopy are used to analyze the microstructure, fatigue fracture, and longitudinal section near initiation. The results indicate that the tensile and fatigue properties of repaired parts after 900 °C heat treatment are superior to those treated at other temperatures. This is attributed to the strong tissue sensitivity of the repaired specimens’ performance. With increasing heat treatment temperature, the secondary α phase in the dimorphic structure tissue thickens. Additionally, the restoration zone develops in layered α phases and becomes truncated, leading to shortening and thickening. The heat‐affected zone undergoes a transformation from a transitional structure to a basket organization. After heat treatment at 1000 °C, the microstructure becomes relatively slender, cracks propagate readily, and the resistance is weakened.This article is protected by copyright. All rights reserved.