Accession Number : ADP004124

Title :   Effects of Oxygen-Contamination-Induced Microstructural Changes on the Reverberation of Ultrasound in Ti-6211 Alloys,


Personal Author(s) : Gruber,G. J. ; Hendrix,G. J.

Report Date : JUL 1984

Pagination or Media Count : 21

Abstract : Titanium alloys of extral low oxygen levels are necessary for manned, deep-diving naval vessels because small amounts of dissolved oxygen markedly increase the brittleness of these alloys at low temperatures. The lack of reliable and an accurate nondestructive method for the determination of interstitial oxygen contamination of titanium forgings and weldments is a serious problem. A pulse-echo ultrasonic technique was used to measure the decay of ultrasound in five Ti-6211 alloy plate specimens containing known concentrations of dissolved oxygen (from 0.075 to 0.290 percent by weight). Surface conditions of the immersed plates had no influence on the ultrasonic results obtained for the bulk of the test specimens. Both the time-specific amplitude and decay rate of the spatially averaged reverberation curves proved to be sensitive indicators of the microstructural variations among the test specimens. The correlation between the ultrasonic-reverberation and oxygen contamination levels was found to be significant (p < 0.08). The present study has confirmed that interstitial oxygen in Ti-6211 forgings and weldments can be monitored through its microstructure mediated effect on the reverberation of a focusable interrogating ultrasonic beam. (Author)

Descriptors :   *Titanium alloys, *Oxygen, *Contamination, *Microstructure, *Ultrasonics, *Reverberation, Weldments, Forging, Nondestructive testing, Decay, Ultrasonic tests, Interstitial, Grain size, Correlation, Metallography, Brittleness, Surface roughness, Naval vessels(Support)

Distribution Statement : APPROVED FOR PUBLIC RELEASE