Ni-Cr-Fe-P系合金填料與UNS S31803雙相不銹鋼間之伽凡尼腐蝕效應

The Effect of Galvanic Corrosion between Ni-Cr-Fe-P Alloys Filler Metal and UNS S31803 Duplex Stainless Steel

本研究以機械球磨配製Ni-Cr-Fe-P系硬焊填料粉末，並用於UNS S31803雙相不銹鋼真空硬焊接合，來探討母材與填料金屬間的伽凡尼腐蝕效應。合金元素的比例選定適當的化學成分，期望獲得金屬填料粉末與UNS S31803雙相不銹鋼基材之腐蝕性質相近的接合件。將此硬焊填料覆於UNS S31803雙相不銹鋼表面，在與硬焊相同條件下熔解及凝固，模擬硬焊接合後填料金屬的成分與金相變化，並利用電化學方法量測硬焊填料與雙相不銹鋼的平衡電位差及伽凡尼腐蝕電流。進一步利用這些填料對UNS S31803雙相不銹鋼進行硬焊，並對硬焊區進行3.5%NaCl的浸泡試驗，其接合處的表面腐蝕型態與電化學伽凡尼腐蝕試驗之趨勢相符。

The purpose of this study is to evaluate the galvanic behavior between UNS S31803 duplex stainless steel and brazing filler metals. The Ni-Cr-Fe-P filler metals were prepared by mechanical alloying using the BNi-7, iron and chromium powders as starting materials. Increasing the adding amount of Fe and Cr powders was increased the deviation of corrosion potential of the filler metal from UNS S31803 plate. However the galvanic corrosion current between the filler metals and UNS S31803 plate were decreased as the adding amount of alloying element increase. From the immersion test, it is shown that weight loss of brazed joint using Ni-22Cr-8.1P-10Fe filler was the lowest among all testing fillers. Immersion test results have been confirmed the results of galvanic test.