22.08.2015   Comprehensive nuclear materials

Mechanical Properties of AuSS After SPNI

Figure 37 shows tensile data of various AuSS (316L, 304L, 316F, JPCA, and 316L-EBW) after SPN irradiations at 100-350 °c223’228’229’249-253 as well as neutron irradiations at around 300 °q254-257 The increase in yield and tensile stress for tests at the irradiation temperature appears to be somewhat lower following SPNI compared to mixed spectrum neutron irradiation, which also produces high levels of He. However, since the alloys used in the different studies are not the same, no clear conclusion can be drawn from this observation. The strength increases plateau above about 10 dpa. In all cases, the uniform elongation falls to less than 1% above about 5 dpa.252 Similar trends are also generally observed in fast reactor irradiations of AuSS.257^258

Figure 38 shows the effect of LANSCE irradia­tions below 160 °C on the fracture toughness of SS316L tested between 50 and 80 °C.223 The fracture toughness for tests at the indicated temperatures for EC316LN irradiated in STIP below 340 °C and SS316L and JPCA irradiated at HFIR at «300 °C is

 

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Figure 36 Comparison of the predicted shift in the Master Curve reference temperature, AT0, with the data shown in Figure 35 showing the drastic embrittling effect of high concentrations of He.

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□ YS, SPN ■ UTS, SPN YS, neutron Ф UTS, neutron

 

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Figure 37 Irradiation dose dependence of yield stress (YS), ultimate tensile stress (UTS), strain to necking (STN), and total elongation (TE) of AuSS irradiated with SPN and fission neutrons and tested at temperatures between 100 and 350 °C.

 

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also shown. The decreases Kjq with dpa have similar trends, although the STIP data show a less regular pattern; however, at higher dpa the toughness falls at 50 MPaVm or less. A similar trend has been previously reported for both fast reactor and mixed spectrum reactor irradiations and is considered to be due to reductions in the uniform strain and strain hardening rates that are not strongly influenced by He.2