| 摘要: | 研究使用慢應變速率測試(SSRT)探討沃斯田鐵系316型不�袗�在288 ℃含氧低氯的水溶液中應力腐蝕斷裂的現象。在高氧含量(0.5~45ppm)環境中，敏 化狀態316型不�袗�之應力腐蝕斷裂相當嚴重，其次是退火狀態，而在低氧含量 (約0.05ppm)的環境中，也有應力腐蝕現象發生，且退火狀態比敏化處理後的要嚴 重。 由結果顯示退火316型不�袗�在高氧含量(9~45ppm)及低氧含量(約0.05ppm)下的應 力腐蝕均為滑移一溶解(Slip-dissolution)的機理，前者在低應力狀態下即會造成A 式穿晶應力腐蝕，而後者須處於高應力下(頸縮後)才會有B式穿晶應力腐蝕現 象。而敏化316型不�袗�在O��>0.5ppm環境下，其二次裂縫分佈屬於A式應力腐 蝕，其斷裂模式分別為沿晶應力腐蝕(O�砥�2.2ppm)和沿晶-穿晶混合式應力腐蝕 (0.5)
The slow strain rate test (SSRT) has been successfully utilized to study the susceptibility of 316stainless steel to stress corrosion cracking (SCC) in low chloride oxygenated water at 288℃. In high oxygenated water (0.5 ~45ppm), sensitized 316 stainless steels suffer most severe SCC, while annealed ones were much less. On the other hand, in low oxygenated water (~0.05 ppm), annealed 316 stainless steelsuffer much severe SCC than the sensitized ones. Results show that the SCC for annealed 316 S.S. in water with both high oxygen content (9-45ppm) and low oxygen (~0.05 ppm) belongs to the slip-dissolution mechanism, and the former suffers type A TGSCC at lower stress level while the latter suffers type B TGSCC at higher stress (after necking).Furthermore, the secondary crack distribution of sensitized 316 S.S. belongs to type A SCC in O�� ≧ 0.5ppm, the fracture mode is IOSCC (O�� ≧ 2.2 ppm) and IGSCC+TGSCC mixed mode (0.5 < O�� < 1.6ppm). However, when the oxygen content is lower than 0.2 ppm, the fracture mode becomes type B TGSCC. |
