Improvement of fatigue properties of duplex-treated ELI Ti6Al4V fabricated by laser powder bed fusion: heat treatment and W-DLC coating under various temperature conditions

This study investigates the effects of a duplex surface treatment, consisting of sub-beta-transus heat treatment followed by W-DLC coating via closed-field unbalanced magnetron sputtering (CFUBMS), on the fatigue behavior of Ti6Al4V ELI alloy fabricated using laser powder bed fusion (L-PBF). Post-processing techniques were analyzed for their influence on fatigue performance under diverse ambient conditions (steady and cyclic). Fatigue tests were conducted using the stress-life methodology at 25 degrees C (room temperature), 50 degrees C, 250 degrees C, -50 degrees C, and cyclic conditions ( -50/ + 50 degrees C). Structural, morphological, and mechanical properties were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Vickers hardness testing. The microstructural analysis highlighted significant strain accumulation near fracture sites and the presence of micropores, which contributed to microcrack initiation. Results demonstrated that test temperature notably influenced fatigue life, significantly reducing under cyclic conditions ( -50/ + 50 degrees C) compared to room temperature. Heat treatment and W-DLC coating notably enhanced fatigue performance across all test conditions by forming a protective barrier and reducing residual stresses.

Journal

JOURNAL OF MATERIALS SCIENCE

Year

2026

Volume

61

Issue

14

Pages

9813-9835

ISSN

0022-2461

eISSN

1573-4803

DOI

10.1007/s10853-026-12488-3

WoS UID

WOS:001712404400001