Fatigue behavior of Ti-6Al-4V alloy modified by plasma immersion ion implantation: temperature effect

• Published in: MATEC Web of Conferences Vol. 165; p. 14001
• Main Authors: Velloso, Verônica, Nozaki, Leonardo, Tapia, Diego, Cioffi, Maria Odila, Oliveira, Rogério, Barboza, Miguel, Voorwald, Herman
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Les Ulis EDP Sciences 01.01.2018
• Subjects: Crystal lattices; Cyclic loads; Deformation; Diffusion layers; Fatigue cracks; Fatigue strength; Fatigue tests; Heating; Ion implantation; Lattice strain; Microstructure; Nitrides; Solid solutions; Temperature effects; Thermal cycling; Titanium base alloys
• ISSN: 2261-236X; 2274-7214; 2261-236X
• DOI: 10.1051/matecconf/201816514001

This research studied Ti-6Al-4V alloy behavior with two (2) different microstructure subjected to nitrogen addition by PIII treatment, with and without sample heating, under cyclic load. PIII conditions, at 390 °C, were DC voltage of 9.5 kV, frequency of 1.5 kHz and pulse of 40 μs. PIII conditions, with sample heating at 800 °C, were 7 kV, 0.4 kHz and 30 μs. Axial fatigue tests were performed on untreated and treated samples for resistance to fatigue comparison. The untreated Ti-6Al-4V had an annealed microstructure, PIII treatment at 390 °C resulted in a microstructure that has no nitride layer or diffusion zone. In the PIII treatment at 800 °C, the microstructure presented nitride layer and diffusion zone. Resistance to fatigue decreased with PIII treatments in both temperatures. At 390 °C, the treatment created deformation regions and cracks on surface due to nitrogen implantation that formed solid solution with titanium and imposed lattice strains on the crystal lattice. At 800 °C, bulk ductility decrease, increasing of αTi proportion in microstructure due to α case formation and the presence of a ceramic layer dropped fatigue resistance of Ti-6A-4V alloy.