304不銹鋼在200～400℃含NaCl水汽環境下之腐蝕行為研究

The Corrosion Behavior of 304 Stainless Steel at 200~400℃ in NaCl-containing Atmospheres

本研究主要是探討304不銹鋼之母材、銲道、熱影響區三種不同區域在溫度200～400℃含NaCl水汽環境下之腐蝕行為。結果顯示，304不銹鋼在母材、銲道、熱影響區三部分的腐蝕動力學皆遵守拋物線型定律，且其腐蝕反應速率皆隨溫度之升高而加快，腐蝕速率以母材最慢，但與銲道之速率差異不大，而熱影響區則最快。鋼材在母材之主要腐蝕產物為Fe2O3及NiCr2O4，Ni(ClO4)- 2.6H2O次之，在銲接部分之主要產物為Fe2O3及Fe3O4為主，FeCr2O4、FeCl3-nH2O次之，而在熱影響區之產物以Fe2O3及Fe3O4為主，FeCr2O4、FeCl3-2H2O、FeCl3-6H2O次之，生成不同型式的氯化物是造成腐蝕速率差異的原因。

The atmospheric-corrosion behavior of SUS304 stainless steel was studied over the temperature range 200~400℃ in a simulated NaCl-containing environment. In general, the results showed that the corrosion kinetics of the base metal, weld metal, and heat-affected zone obeyed the parabolic rate law. The corrosion rate increased with increasing temperature. The corrosion rate of the heat-affected zone were faster than other parts. The corrosion products formed on the base metal consisted of Fe2O3, NiCr2O4, Ni(ClO4)-2.6H2O, on the weld metal consisted of Fe2O3, Fe3O4, FeCr2O4 and FeCl3-nH2O, and on the heat-affected zone consisted of Fe2O3, Fe3O4, FeCr2O4, FeCl3-2H2O and FeCl3-6H2O. The formation of different chlorides is responsible for the various corrosion rates.