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Abstract
The fatigue and tensile properties of coarse-grained a-titanium containing 0.085 wt.- % oxygen have been determined over the temperature range −196°C (77 K) to 800°C (1073 K). Metallographic examination of fatigue specimens has shown the following characteristics. In the range −196 to 150°C (77–423 K) fatigue damage was associated with internal {ll2l}-type twins and these acted as preferential crack-propagation paths. In the range 200–500°C (473–773 K) twin formation was not observed and surface-nucleated fatigue cracks propagated transgranularly. Above 600°C (873 K) a transition to inter granular surface-nucleated cracking took place, while above 700°C (973 K) grain-boundary cavitation and crack growth were noted. At ∼ 300°C (573 K) a peak in the fatigue response of α-titanium occurred. This temperature corresponded to that at which dynamic strain-ageing was observed and at which twin/interface and grain-boundary cracking were absent.