焊接304型不銹鋼在3.5% NaCl溶液中之腐蝕行為

Corrosion behaviors of welded AISI 304 stainless steels in 3.5%NaCl solution

沃斯田鐵型不銹鋼粒間腐蝕的敏化溫度約在450℃至850℃之間，而不銹鋼在銲接過程中正在此溫度範圍間，為要瞭解銲接製程中，減少銲接入熱與銲道急冷這兩項因素在減少碳化物析出的效果，本文以ASTM A262-93a規範、配合直流極化掃描及交流阻抗法來評估改善不銹鋼銲接製程之可能性。實驗即由觀察銲道、熱影響區、及母材區之顯微組織圖中比較各區域之腐蝕電位、電流密度及交流總阻抗值進而發現銲接入熱量的減少與銲道急冷方式，對於改善銲道退化有著顯著的助益，本就結果顯示沃斯田鐵型不銹鋼焊接時對入熱量控制的程序有其顯著的必要性。

The sensitization temperatures of austenitic stainless steel are between 450 and 850℃. However, it is inevitable that the Gas Tungsten Arc Welding (GTAW) process has to be heated or cooled in this range. The ASTM A262-93a corrosion practice and effects of heat flow input and weld quench procedure on the sensitization are then studied. Corrosion behaviors are observed and shown from potentiodynamic polarization and AC impedance measurements. Minimized the input of heat flow seems to be the most effective for its corrosion resistance. The employed sensitization measurements and studying results suggest that heat-generation control will be crucial for AISI 304 stainless steel in GTAW welding.