Sensitivity Of The Creep Rupture Properties Of Nickel Base Superalloy Sheet To Sharp Edge Notches In The Temperature Range Of 1000 1400 F

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ISBN 13 :
Total Pages : 0 pages
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Download or read book Sensitivity of the Creep-Rupture Properties of Nickel-Base Superalloy Sheet to Sharp Edge-Notches in the Temperature Range of 1000 Deg. - 1400 Deg. F. written by and published by . This book was released on 1969 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigations are now in progress to evaluate the severe time- dependent, edge-notch sensitivity known to occur in thin sheet nickel-base superalloys exposed under stress at 1000 and 1200F. Studies of Rend 41, Waspaloy and Inconel 718, over a wide range of heat-treated conditions, has served to define the scope of this problem in 0. 026-inch thick sheet. In addition, exploratory data have been obtained on the influence of notch acuity and sheet thickness on the notch sensitivity. Both smooth and edge-notched specimens fractured by the initiation and growth of intergranular cracks, followed by abrupt transgranular fracture due to the increase in stress caused by creep cracking. Analysis of these processes showed that the degree of notch sensitivity was strongly dependent upon the effect of the notches on the time required for the initiation of the creep crack and the early stages of its growth. There were some differences among alloys and within an alloy with heat treatment and test temperature. The notch sensitivity was not exhibited for the testing time periods considered when sheet thickness was increased from 0.026- to 0.050-inch. This, together with other considerations, suggests that the stress and strain state is a major factor. Until this is understood, however, it is not possible to correlate notch sensitive behavior with precise microstructural features or mechanical properties.