Studies to determine the effect of neutron environment on the stress-rupture properties of A-286, Hastelloy X, and René 41 alloys are described. Specimens were irradiated in the Engineering Test Reactor at approximately 540 and 650 C to fast neutron dosages of 4 to 11 × 1019 nvt (En ≧ 1 Mev). Postirradiation stress-rupture tests were conducted at 540 and 650 C. The effect of reheat treatment following irradiation was investigated.
The results indicate that the stress-rupture strengths of A-286 and Hastelloy X alloys at 540 and 650 C were significantly reduced by irradiation. A similar effect was observed in René 41 at 650 C. Complete reheat treatment following irradiation did not restore the radiation-induced loss in strength in A-286 alloy at 540 or 650 C, or in René 41 at 650 C. Reheat treatment appeared to effect recovery in the rupture strength of Hastelloy X at 540 C, but not at 650 C.
The A-286 alloy showed substantial reductions in rupture ductility, particularly at 650 C. A similar loss in ductility in one of two heats of René 41 was observed at 650 C. The ductility of Hastelloy X, though affected, remained at relatively high levels.
Structural studies have been initiated on control and irradiated specimens of A-286 alloy. Initial results are discussed.