CRACKING BEHAVIOR OF IRRADIATED HEAT-AFFECTED ZONE SPECIMENS OF TYPE 304 AND 304L STAINLESS STEEL WELDS IN HIGH-PURITY WATER

摘要

Stress corrosion cracking of austenitic stainless steel weldments is of great interest for light water reactors. Due to the high heat input of weld process and post-weld neutron irradiation, weld heat-affected zone could be subject to both sensitized microstructure and irradiation embrittlement. In this work, cracking behavior of irradiated HAZ specimens has been investigated for Type 304 and 304L submerged arc and shielded metal arc welds that were irradiated to 0.75 and 2 dpa. The specimens are either as-welded or thermally-treated at 500"Cfor 24 hr prior to irradiation. Crack growth rates have been measured on 1/4T-CT specimens, and comparisons have been made between as-welded and thermally-treated specimens. Relatively high crack growth rates were observed for all HAZ specimens, but no significant difference is noticed between the as-welded and thermally-treated HAZ specimens. Fracture toughness was measured in these HAZ specimens to evaluate irradiation embrittlement and the effect of post-weld thermal-treatment.