Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
Page : 36 pages
File Size : 44,6 Mb
Release : 2018-08-17
Category : Electronic
ISBN : 1725780429
External Stress-Corrosion Cracking of a 1. 22-M-Diameter Type 316 Stainless Steel Air Valve by National Aeronautics and Space Administration (NASA) Pdf
An investigation was conducted to determine the cause of the failure of a massive AISI Type 316 stainless steel valve which controlled combustion air to a jet engine test facility. Several through-the-wall cracks were present near welded joints in the valve skirt. The valve had been in outdoor service for 18 years. Samples were taken in the cracked regions for metallographic and chemical analyses. Insulating material and sources of water mist in the vicinity of the failed valve were analyzed for chlorides. A scanning electron microscope was used to determine whether foreign elements were present in a crack. On the basis of the information generated, the failure was characterized as external stress-corrosion cracking. The cracking resulted from a combination of residual tensile stress from welding and the presence of aqueous chlorides. Recommended countermeasures are included. Moore, Thomas J. and Telesman, Jack and Moore, Allan S. and Johnson, Dereck F. and Kuivinen, David E. Glenn Research Center NASA-TP-3190, E-6810, NAS 1.60:3190 RTOP 505-62-84...