Enhancing low-cycle fatigue performance of high-efficient laser additively manufactured TC11 titanium alloy: Mechanisms of cyclic softening/hardening and microstructural refinement

作者：Ning Guo, Jiang Yu, Qingjun Zhou, Jilai Wang, Guangchun Xiao, Bingtao Tang, Zhongguo Zhang · 发表于：Journal of Materials Research and Technology · 年份：2025 · DOI：10.1016/j.jmrt.2025.03.303 · 被引用次数：9 · 研究领域：Additive Manufacturing Materials and Processes、Titanium Alloys Microstructure and Properties、Additive Manufacturing and 3D Printing Technologies

The enhancement of low-cycle fatigue (LCF) performance of large structural components manufactured from TC11 titanium alloy fabricated via laser powder directed energy deposition (LP-DED) in the aerospace field is a challenging issue in achieving high reliability. This study systematically investigates the LCF behavior of TC11 titanium alloy fabricated via LP-DED and subjected to three double annealing regimes. Fully reversed strain-controlled fatigue tests were conducted under strain amplitudes ranging from 0.4 % to 1.2 %, accompanied by comprehensive microstructural characterization using EBSD , TEM, and fractography . Results reveal that cyclic softening/hardening is governed by the competition between back stress from geometrically necessary dislocations (GNDs) accumulation and friction stress from dislocation annihilation. The 950 °C + 550°C-annealing treated specimen demonstrated enhanced LCF life due to finely refined α phase regions with an average thickness of 4.4 μm, which facilitated crack deflection through localized stress redistribution and strain incompatibility. Microstructural analysis demonstrated that basketweave structures with discontinuous α GB phases enhanced resistance to crack propagation by accumulating dislocations at phase boundaries, delaying microvoid coalescence . The critical role of annealing temperature in tailoring microstructural heterogeneity and dislocation dynamics is underscored by these findings, which provide valuable insights for enh...