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Risk Assessment for Titanium Pressure Vessels Operating Inside the ARES I's Liquid Hydrogen Tank EnvironmentTitanium alloy (Ti-6-4) is currently being proposed for the manufacturing of pressure vessels (PV) for storage of compressed helium gas, which are mounted inside the ARES I's liquid hydrogen (LH2) tank. At cryogenic temperature, titanium alloys usually have the highest strength-to-weight ratio property and have been considered as the metallic materials of choice for lightweight PV operating in LH2 environment. Titanium PV s are also considered as heritage hardware because they have been used by NASA for the Saturn IV-B rocket s LH2 tank in the mid 1960 s. However, hydrogen embrittlement is possible if Ti-6-4 alloy is exposed to gaseous hydrogen at certain pressure and temperature during the LH2 tank filling and draining operations on the launch pad, and during the J2X engine burn period for the ARES I s upper stage. Additionally, the fracture toughness and ductility properties of Ti-6-4 are significantly decreased at cryogenic temperature. These factors do not necessary preclude the use of titanium PV in hydrogen or at cryogenic applications; however, their synergistic effects and the material damage tolerance must be accounted for in the mission life assessment for PV s, which are considered as fracture critical hardware. In this paper, an overview of the risk assessment for Ti-6-4 alloy, strategy to control hydrogen embrittlement and brief metallic material trade study for PV operating in LH2 tank will be presented.
Document ID
20080036522
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Lee, Jonathan A.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
August 24, 2013
Publication Date
June 23, 2008
Subject Category
Metals And Metallic Materials
Meeting Information
Meeting: 2008 National Space and Missile Materials Symposium
Location: Henderson, NV
Country: United States
Start Date: June 23, 2008
End Date: June 27, 2008
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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