Minimum fatigue striation spacing and its stress amplitude dependence in a commercially pure titanium

Abstract

We report the fatigue striation spacing of commercially pure titanium with respect to stress amplitude. Rotating bending fatigue tests were performed at 150, 175, 200 and 227 MPa in which samples did not fail at 150 MPa. No fatigue striation up to a certain crack length is observed for the studied conditions. For each condition, a minimum striation spacing value is found that decreases from 0.45 to 0.36 to 0.24 μm with increasing stress from 175 to 200 to 227 MPa, respectively. The minimum striation spacing remains constant up to a certain crack length for each condition. Thereafter, it starts increasing with crack length. It is quite understandable that the constant striation spacing over a certain crack length may not represent the macroscopic fatigue crack growth rate. The fatigue crack growth mechanism during the constant striation spacing region has been discussed in detail. K E Y W O R D Scommercially pure titanium, fractrography, metal fatigue, fatigue striation

Data analysis of striation spacing, lifetime, and crack length in crankshaft ductile cast iron under cyclic bending loading through high-cycle fatigue regime

“…However, Ahmed et al. [7] reported that striation spacing increased when the stress decreased for commercially pure titanium. They illustrated that the threshold crack length was 2.5, 1.9, and 1.4 mm, where striation spacing started to increase at 175, 200, and 227 MPa, respectively [7] .…”

“…They illustrated that the threshold crack length was 2.5, 1.9, and 1.4 mm, where striation spacing started to increase at 175, 200, and 227 MPa, respectively [7] . The related minimum value for striation spacing was also reported as 0.45, 0.36, and 0.24 µm, for the mentioned applied stress [7] .

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Multiaxial low cycle fatigue behavior and life prediction of CP‐Ti under non‐proportional stress‐controlled mode

“…As a material with high specific strength, good corrosion resistance and many other excellent characteristics, 1,2 commercial pure titanium (CP‐Ti) is widely used in aviation and chemical equipment fields. Many fatigue failures of piping and vessels manufactured with CP‐Ti were reported under a variety of different conditions of cyclic loading 3–6 .…”