Irradiation creep in Type 316 stainless steel and US PCA with fusion reactor He/dpa levels

Irradiation creep was investigated in type 316 stainless steel (316 SS) and US Fusion Program PCA using a tailored spectrum of the Oak Ridge Research Reactor in order to achieve a He/dpa value characteristic of a fusion reactor first wall. Pressurized tubes with stresses of 20 to 470 MPa were irradiated at temperatures of 330, 400, 500, and 600/sup 0/C. It was found that irradiation creep was independent of temperature in this range and varied linearly with stress at low stresses, but the stress exponent increased to 1.3 and 1.8 for 316 SS and PCA, respectively, at higher stresses. Specimens of PCA irradiated in the ORR and having helium levels up to 200 appM experienced a 3 to 10 times higher creep rate than similar specimens irradiated in the FFTF and having helium levels below 20 appM. The higher creep rates are attributed to either a lower flux or the presence of helium. A mechanism involving interstitial helium-enhanced climb is proposed. 17 refs

Tensile properties of 20% cold-worked titanium-modified type 316 stainless steel irradiated in HFIR

An alloy of type 316 stainless steel with the addition of 0.23% Ti (316 + Ti) has been irradiated in the 20% cold-worked condition in the HFIR (a mixed fast and thermal neutron spectrum reactor) and tested near the irradiation temperature in the range of 300 to 600/sup 0/C. Tensile tests were performed following irradiation to fluence levels of 0.63 to 2.1 x 10/sup 26/ n/m/sup 2/ (E > 0.1 MeV) and helium levels of 200 to 1000 at. ppM. The 316 + Ti exhibited higher strength and lower ductility than similarly irradiated type 316 stainless steel (316 SS). However, the tensile elongation of 316 + Ti tends to saturate with increasing fluence at 575/sup 0/C whereas the elongation of 316 SS continues to fall for the fluences investigated. Reduction of area is similar for the two alloys, and 316 + Ti shows completely ductile rupture at 450/sup 0/C and below. The differences in strength and ductility are attributed to the influence of TiC precipitates trapping helium in the matrix

Types of insects in Amer. Mus. Nat. History

p. 353-379 ; 24 cm.Includes bibliographical references

Behavior of Type 316 stainless steel under simulated fusion reactor irradiation

Fusion reactor irradiation response in alloys containing nickel can be simulated in thermal-spectrum fission reactors, where displacement damage is produced by the high-energy neutrons and helium is produced by the capture of two thermal neutrons in the reactions: /sup 58/Ni + n ..-->.. /sup 59/Ni + ..gamma..; /sup 59/Ni + n ..-->.. /sup 56/Fe + ..cap alpha... Examination of type 316 stainless steel specimens irradiated in HFIR has shown that swelling due to cavity formation and degradation of mechanical properties are more severe than can be predicted from fast reactor irradiations, where the helium contents produced are far too low to simulate fusion reactor service. Swelling values are greater and the temperature dependence of swelling is different than in the fast reactor case

Temperature dependence of the deformation behavior of type 316 stainless steel after low temperature neutron irradiation

A single heat of solution annealed 316 ss was irradiated to 7 and 18 dpa at 60, 200, 330, and 400 C. Tensile properties were studied vs dose and temperature. Large changes in yield strength, deformation mode, strain to necking (STN), and strain hardening capacity were seen. Magnitude of the changes are dependent on both irradiation temperature and neutron dose. Irradiation can more than triple the yield strength and decrease STN to <0.5% under certain conditions. A maximum increase in yield strength and a minimum in STN occur after irradiation at 330 C but failure mode remains ductile

Notes on Pero species

11 p. ; 24 cm