Influence of Carbon and Nitrogen on Corrosion Resistance of High Purity Fe-50mass % Cr Alloy

Abstract

High purity Fe-50rnass%Cr alloys containing (C+N) in the range of 30 to 500 mass pprn were prepad and their corrosion resistance was investigated. Pitting potential in a 3.5mass%NaCl solution at 343K rose with reducing (C+N) content. Alloys containing (C+N) at less than 100 mass ppm did not sustain pitting corrosion. However, alloys containing 500 mass ppm (C+N) corroded severely in 6%FeC13+1/20N HCI solutions. Heat treatment at 923K was recognized as influencing corrosion resistance due to precipitation of carbonitrides only in the case of the alloy containing 500 mass ppm (C+N).

Corrosion Resistance of a High Purity Fe–50 mass% Cr Alloy

“…In fact, the high C and N alloy had twenty times as many precipitates as the ultra-low C and N alloy [2]. That is one of the reasons why the high C and N alloy had more corrosion pits than the ultra-low C and N alloy.…”

“…A field exposure test (JIS Z 2381) was conducted on specimens with a size of 50 Â 75 mm 2 , which had been finished with polishing compound #1000 and set at a southward inclination of 36 with respect to the ground in an exposure test field. The field has 10 m distance from the bulkhead quay.…”

“…Kato et al [2] reported that an ultralow C and N Fe±50 mass% Cr alloy exhibited excellent corrosion resistance in electrochemical corrosion tests.…”