SS3471有18-8訣斯田系列之不鏽鋼，主要是加入合金元素Nb與Tat)、防止碳化物之析 出。雖然SS347通常設計使用於高溫且具腐蝕環境中，但不適當的熱處理會減忌弱S347的腐蝕抗t生O故而且已們使用雙程動態、極化掃描方法來研究熱處理溫度對SS347敏化行為的影響。在實驗上我們發現以下兩個現象:(1)敏化溫度為550°C及850°C時，不鏽鋼347每文化的程度不隨敏化熱處理時間增加而改變;550°C時敏化閃溫度低，碳擴散速率慢而不顯著， 850°C時閃碳化鈕穩定眼的效 應，使敏化不隨時間而惡化。(2 )在敏化溫度為650°C及750°C時，隨著敏化時間的增加，敏化程度也隨時間增加而遞增。且成線性關係，敏化溫度650°C時敏化程度增加最快O敏化程度是碳化鋁析出與鋁原子擴散消5耳鋁乏區之間動態平衡的結果。

SS347 is one of the 18-8 series austenitic stainless steels. The major improvement for this kind of stainless steel is to add alloying elements of Nb and Ta. The purpose of adding these elements is to prevent the precipitation of carbide and the consequent sensitization of the steel. Although SS347 is usually designed for utilizing in the high temperature and corrosive environment, improper heat treatment would decrease the corrosion resistance of SS347. We use the doubleloop electrochemical potentiokinetic reactivation (DL-EPR) to study the effect of heat treatment temperature on the sensitization behavior of SS347 . Two phenomena were observed as follows:1. Degree of sensitization of SS347 undergoing 550 and 850 heat treatment wouldn’t change as the sensitization
time increases. Low carbon diffusion rate limits the formation of chromium carbides at 550 . Niobium catches more carbon atoms to prevent the formation of chromium carbides at 850 . 2. Degree of sensitization of SS347 undergoing 650 and 750 heat treatment would increase linearly as the
sensitization time increases. D.O.S. is the result of a balance between the rate of the precipitation of chromium carbide and the rate at which the chromium-depleted zones are eliminated by diffusion.