Quantitative analysis of microstructural effects on fatigue crack growth in widmanstätten Ti-6A1-4V and Ti-8Al-1Mo-1V

✍ Scribed by G.R. Yoder; L.A. Cooley; T.W. Crooker

• Publisher: Elsevier Science
• Year: 1979
• Tongue: English
• Weight: 652 KB
• Volume: 11
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(79)90138-3

✦ Synopsis

Analysis of fattgue crack growth behavior of five beta-annealed alloys indicates significant effects of mlcrostructure upon the logarithmic plot of fatigue crack growth rate (da/dN) vs stress-intensity range (AK). Each plot exhibits a bilinear form with a transition at AKr, the position of which lies between 18 and 31 MPa. m It2 for the five alloys. Comparison of mean Widmanstitten packet size to cyclic plastic zone size, as analyzed on the b~is of different models, indicates their equality at AKr. Greater clustering of the packet size distribution about the mean value affects a decrease in hypertransitional exponent (ms) in the power law, da/dN = C(AK)', and a simultaneous increase in the sharpness of transition. Hypertransitional exponents for the five alloys lie between 2.9 < mA--< 4.7, whereas hypotransitional exponents lie between 5.9 -< ms -< 7.6. Hypotransitional growth rates vary inversely with mean packet size, with a 20-fold reduction in da/dN observed for a 3.5-fold increase in mean packet size.