Combined effects of neutron irradiation and stress corrosion on embrittlement of austenitic stainless steels

The effects of neutron irradiation on the SCC susceptibility, intergranular corrosion and tensile properties for the austenitic stainless steels were investigated. (1) The neutron irradiation caused a little increase in the intergranular corrosion sensitivity which was tested in the boiling H2SO4-CuSO4 aqueous solution for the sensitized 304 and 316 stainless steels. (2) For the both 304 and 316 stainless steels was observed the neutron irradiation-induced embrittlement, i.e. the increase in strength and the ductility loss. The addition of a small amount of Yttrium or Lanthanum-Cerium was proved to be effective in the improvement of the above irradiation embrittlement of the Type 316 stainless steel. (3) For the sensitized stainless steels, a little increase due to neutron irradiation was found in the intergranular stress corrosion cracking susceptibility which was evaluated by the method of constant extension rate test in the 533 K high purity water. The above tendency of IGSCC susceptibility was accentuated by the higher neutron fluence. The IGSCC susceptibility of the sensitized 316 stainless steel in 533 K high purity water was not influenced by the addition of a small amount of Yttrium or Lanthanum-Cerium. (author)