A STUDY OF THE EFFECTS OF NUCLEAR RADIATION ON HIGH-STRENGTH AEROSPACE VEHICLE MATERIALS AT THE BOILING POINT OF HYDROGEN (-423 FE
The problem of radiation damage occurring in structural materials at - 423 deg F became of major importance during the studies of nuclear powered upper stage rockets. In this type of vehicle, large pressurized propellant tanks containing liquid hydrogen at -423 deg F are subjected to large doses of both neutron and gamma fluxes. Thus the structural materials experience a combined environment of cryogenic temperature and nuclear radiation. To study the nature of these effects, samples were exposed to an integrated fast neutron flux of about 2 x 10/sup 17/ (E >.33 mev) nvt while being soaked in liquid hydrogen. Aiter the radiation exposure the samples were subjected to tensile tests while being held at -423 deg F without intervening warmup. The alloys studied were 301 and 310 stainless steels cold rolled 60 and 75 percent respectively, 5 Al-2-1/2 Sn titanium(A110AT), and 2014-T6 aluminum. The tensile tests performed gave yield strength, tensile strength, elongation, notched tensile strength (K/sub t/ = 6.3), and the tensile strength of simple heliarc butt welded joints. Samples were tested in the unirradiated and irradiated conditions at both 70 deg F and - 423 deg F. The largest and most consistent effect of cryogenic irradiation was a decrease in tensile strength and elongation after irradiation at -423 deg F. This effect varied from a 27% decrease in tensile strength for the 301 stainless steel to a 3% decrease for the 5 Al-2-1/2 Sn titanium. The effect of cryogenic irradiation was to severely restrict the amount of plastic deformation the samples could sustain after yield and prior to fracture. This phenomenon was accordance with the theory that neutron radiation acts to introduce vacancies and interstitials which restrict the amount of plastic strain the samples can withstand before fracture. This effect was believed to be more severe at cryogenic temperatures because the neutron generated vacancies and irterstitials can diffuse out at the higher temperatures, but are " frozen in" at cryogenic temperatures. Notched tensile tests showed that small amounts of embrittlement occurred in the 301 stainless steel after cryogenic irradiation, while the 310 stainless steel showed no embrittlement. It was believed that this condition resulted from the radiation induced embrittlement of the body centered martensite phase which constituted about 45% of the 301 stainless steel samples. The 5 Al-2- l/2 Sn titanium and the 2014-T6 aluminum alloys showed no embrittlement as a result of cryogenic irradiation. (auth)
- Research Organization:
- General Dynamics/Astronautics, San Diego, Calif.; and General Dynamics/Fort Worth. Div. of General Dynamics Corp., Fort Worth, Tex.
- NSA Number:
- NSA-16-013640
- OSTI ID:
- 4786184
- Report Number(s):
- ERR-AN-085
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-62
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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