Quasi-static crack propagation in Ti-6Al-4V in inert and aggressive media

Abstract

High strength-to-weight ratio Ti-6Al-4V alloy is used in many engineering applications. Its surface oxide film can protect the substrate from interaction with a lot of corrosive environments. Unfortunately, this surface layer can be damaged under mechanical and chemical actions with a consequent reduction in corrosion resistance. A characterization of the untreated alloy under quasi-static loading is here provided. Inert and aggressive environments have been investigated and the influence of the notch geometry of the alloy has also been analyzed.

Strength of notched Ti-6Al-4V specimens not subjected to solution treatment and over-aging under cyclic loading

“…The first step was the determination of the alternating stress to failure σa (Nlife, R = -1) at the fatigue life Nlife starting from the S-N (σa-Ncycles) curves for each notched specimen not subjected to STOA (Figure 3a). The S-N curves for the three notched specimens with the three corresponding values of stress concentration factor SCF were built taking into consideration the brittle behavior of the alloy observed in [19]. In the analysis it was assumed that the alternating stress to failure at a fatigue life of 1000 loading cycles corresponds to the stress which induces static failure, i.e.…”

“…Given the σa (Nlife, R = -1) value calculated in the first step, a Haigh diagram was built for each notched specimen. Even in this diagram the brittle behavior of the alloy observed in [19] was considered, dividing YS by SCF to define the yield line and UTS by SCF to define the fatigue limit curve (Goodman line). The yield domain is defined by the area between the vertical axis of the diagram, the horizontal axis, and the yield line.…”

“…The behavior of STOA-treated Ti-6Al-4V in inert and aggressive environments and under quasi-static and fatigue loads is presented in [13][14][15][16][17]. In [18,19] the behavior of the Ti-6Al-4V alloy not subjected to the STOA treatment under quasi-static loading is described for different notches and different environments.…”

Fracture Surface of a Ti-6Al-4V Specimen with EDM Notches Tested under Quasi-Static Loading in Methanol

“…This study is the extension of the study presented in [16] and [18]. The tested specimens were manufactured from a Ti-6Al-4V raw plate supply and were not subjected to STOA.…”

“…This paper aims at summarizing the results of the studies on the behavior of Ti-6Al-4V under quasi-static loading in different environments when this alloy is not subjected to STOA (solution treatment and over-aging) [16,18]. Different notch shapes are presented in order to evaluate their contribution on the strength of the alloy.…”