| 摘要: | 沸水式及壓水式反應器內部材質主要為沃斯田鐵系不�袗�，隨著材質金 相組織、機械強度及環境條件的變化，即可能引發應力腐蝕破裂(SCC)。 本研究使用慢應變速率測試方法，來探討沃斯田鐵系AISI 316,304,lnconel-600以及 肥粒鐵系AISI 410及Spa-Cure不�袗�在288℃含氧低氯的水溶液中應力腐蝕破裂的 現象。其中以316型不�袗�為主要研究對象，而其餘材料的耐SCC的程度將與316 型不�袗�做一比較研究。 在高氧含量(0.5~45ppm)環境下，敏化狀態316型不�袗�及410型不�袗�的SCC情況 最為嚴重，其次是退火狀態316型不�袗�，而在低氧含量(約0.05ppm)的環境下， 只有316型不�袗�有SCC的現象發生，且退火狀態又比敏他處理的來得嚴重。而 敏化退火與材質主要為沿晶及穿晶破裂，在低氧含量時敏化不�袗�材料則主要為 穿晶破裂。由結果顯示退火型316不�袗�在高氧含量(9~45ppm)及低氧含量(約 0.05ppm)下的SCC機構均為滑移一溶解(slip dissolution)，前者在低應力狀態下即會 造成SCC，而後者須處於極高應力下(頸縮後)才會有SCC現象發生。
Austenitic stainless steels have been extensively applied to lightwater reactors (LWR) such as boiling water reactors (BWR) andpressuJsed water reactors (PWR). However, austenitic stainless steels canexperience chloride stress corrosion cracking (SCC) under specificmetallurgical, mechanical and environmental conditions. This report presents data concerning the incidence of crackingduring slow strain rate tests performed on AISI 316, 304, 410 stainlesssteel, lnconel-600 and Sea-Cure stainless steel at 288 -C in anenvironment of water containing chloride at various levels and at arange of oxygen contents. The results are compared with data, mainly for316 stainless steel. The stress corrosion cracking performed on sensitised 316 and 410 areseverer than annealed 316 stainless steel in high temperature watercontaining high oxygen content(0.5~4.5ppm). SCC only perfomed on 316stainless steel in low oxygen content (about 0.05ppm). The predominantcracking modes for annealed and sensitized material were transgranularand intergranular, respectively, except that in low oxygen, sensitizedmaterial displayed transgranular cracking. The present results for annealed 316 significantly proved themechanism of SCC attributing to slip-dissolution in high oxygencontent (9~45ppm) and low level (less 0.05ppm)the former SCC occursonly in low stress state, the later SCC occurs only in the necked region. |
