EXPERIMENTAL STUDY OF THE EFFECT OF NOTCH DEPTH ON FATIGUE FAILURE OF TC4 TITANIUM ALLOY

Guifeng Yu; Wenjie Peng; Yongmao Xiao; Gang Yu; Jinlong Wang

doi:10.17222/mit.2025.1536

Guifeng Yu Marine Engineering College, Dalian Maritime University, Dalian 116026, China
Wenjie Peng School of Mechanical and Electrical Engineering, Gongqing Institute of Science and Technology, Jiujiang 332020, China
Yongmao Xiao School of Mechanical and Electrical Engineering, Gongqing Institute of Science and Technology, Jiujiang 332020, China
Gang Yu Institute of Intelligent Transportation, Hubei University of Arts and Science, Xiangyang 441053, China
Jinlong Wang Marine Engineering College, Dalian Maritime University, Dalian 116026, China

DOI: https://doi.org/10.17222/mit.2025.1536

Keywords: high-cycle fatigue, notch depth, EBSD, TC4 alloy

Abstract

Notch size is a critical factor influencing the fatigue behavior of titanium alloys. This study investigates TC4 titanium-alloy notched specimens under three distinct notch depth conditions through fatigue testing. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) are employed to analyze the microscopic morphology of fracture surfaces and grain boundary evolution. The results demonstrate that as the notch depth increases, ductile fracture characteristics diminish progressively. The intensified stress concentration induced by deeper notches reduces intergranular bonding strength, leading to significant alterations in grain orientation distributions and boundary angles within individual fracture surfaces. Building upon the Basquin model, a modified life-stress correction equation incorporating notch depth as a primary influencing factor is proposed. This enables the construction of S-N curves for TC4 titanium alloy under varying notch depth conditions. Furthermore, systematic characterization of fracture-surface morphology evolution reveals that notch depth amplifies stress concentration effects while constraining plastic deformation capability. The findings provide theoretical insights for optimizing structural design and establishing a scientific foundation for lifetime assessment of TC4 titanium alloy components. This research holds significant theoretical implications and a practical value for ensuring operational reliability and durability evaluation of TC4 titanium alloys in critical engineering applications.

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