本研究探討316L不銹鋼銲件銲道與母材於含有氯化鈉（NaCl）、草酸（Oxalic acid, H2C2O4）、果膠（D-Galacturonic Acid, pectin）等楊桃汁主要成份之水溶液中的耐蝕性質差異。銲道之微觀組織、組成相之晶體構造與分佈以及化學成分分佈等性質，利用掃瞄式電子顯微鏡(SEM)、X光繞射儀(XRD)及電子背向繞射儀（EBSD）等進行分析。銲件之母材與銲道之耐蝕性質則藉由動電位極化曲線、定電位等測試結果加以評估；電化學測試後試片之腐蝕形貌則以SEM加以觀察。
由金相及XRD分析結果可知，316L不銹鋼母材為γ-austinite之單相結構；銲道則呈δ-ferrite與γ-austinite 之雙相結構，經EBSD分析，其δ-ferrite所佔之面積分率約4%。
由動電位極化曲線測試的結果可知，在單組成之水溶液中，316L不銹鋼銲件（不論母材或銲道）在草酸或果膠水溶液中皆具有寬廣（超過1.1 V）的鈍化電位區間。於0.06 M氯化鈉水溶液中，316L不銹鋼母材與銲道的孔蝕敏感性有別，前者孔蝕電位為+0.37VSCE，遠高於後者（-0.13 VSCE）。在0.06 M氯化鈉水溶液中分別添加草酸及果膠，皆可促進316L不銹鋼銲道的鈍化而抑制孔蝕的發生。上述二種添加劑對於孔蝕的抑制效果與其濃度有關，對於銲道的孔蝕的抑制作用更為顯著。不過，當果膠添加於0.06 M氯化鈉水溶液中時，雖然仍可提升316L不銹鋼銲道的孔蝕電位而具有抑制孔蝕的效果，但是對於316L不銹鋼母材卻會使其孔蝕電位降低，而具有促進孔蝕的作用。

The corrosion behaviors of 316L stainless steel and its weld in the aqueous solution containing the main constituent in carambola juice, namely sodium chloride (NaCl), oxalic acid (H2C2O4) and pectin (D-Galacturonic Acid), respectively, were investigated. The crystal structure, phase and chemical composition distribution ,and the microstructure of the weld were analyzed by using SEM, XRD, and EBSD. The corrosion performance of both base metal and weld was evaluated by conducting potentiodynamic polarization curve measurement and potentiostatic etching in the above solutions. The corrosion morphology of the specimens after electrochemical tests was examined by SEM.
Metallography and XRD analyses indicated that the 316L stainless steel matrix exhibited single phase of γ-austinite, while the welded alloy exhibited a dual phase of γ-austinite and δ-ferrite. The area fraction of the δ-ferrite determined by EBSD was about 4%.
Polarization curve tests revealed that an over 1.1V range of passive potential for alloys of weld or base metal in the oxalic or pectin aqueous solution. However, pitting sensitivity was different between the weld and the matrix, having a pitting potential of +0.37VSCE and -0.13 VSCE for the former and later alloys, respectively 0.06M NaCl aqueous solution adding oxalic acid or pectin would inhibit the pitting corrosion at the weld, and the inhibitive effect of the former two additions was related to their concentration. However, the weld in the NaCl aqueous solution adding pectin would increase the pitting potential and inhibit the pitting corrosion, but the matrix alloy in the NaCl aqueous solution adding pectin would decrease the pitting potential and enhance the pitting corrosion.

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