Nitinol tubes were manufactured from Standard Grade VIM-VAR ingots using Tube Manufacturing method ''TM-1.'' Diamond-shaped samples were laser cut, shape set, then fatigued at 37°C to 10 7 cycles. The 50, 5, and 1% probabilities of fracture were calculated as a function of number of cycles to fracture and compared with probabilities determined for fatigue data published by Robertson et al. (J Mech Behav Biomater 51:119-131, 2015). Robertson tested similar diamonds made from the same standard grade of Nitinol as in the current study, two other standard grades of Nitinol, and two high-purity grades of Nitinol expressly designed to improve fatigue life. Robertson's tubes were manufactured using Tube Manufacturing method ''TM-2.'' Fatigue performance of TM-1 and TM-2 diamonds were compared: At 10 7 cycles, strain amplitudes corresponding to the three probabilities of fracture of the TM-1 diamonds were 2-3 times those of the TM-2 diamonds made from the same grade of Nitinol, and comparable to TM-2 diamonds made from the higherpurity materials. This difference is likely a result of the differences in tube manufacturing techniques and effects on resulting microstructures. Microstructural analyses of samples revealed a correlation between the median probability of fracture and median inclusion diameter that follows an inverse power-law function of the form y & x -1 .
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