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HAYNES® Alloys

Localized Corrosion Data

Critical Pitting Temperature (CPT) and Critical Crevice Temperature (CCT)

HYBRID-BC1® alloy exhibits exceptional resistance to pitting and crevice corrosion, as evident from the table below. To assess the resistance of nickel alloys and stainless steels to chloride-induced pitting and crevice attack, it is customary to measure their CPT and CCT in acidifi ed 6 wt.% ferric chloride, in accordance with the procedures defi ned in ASTM Standard G 48.

These values represent the lowest temperatures at which pitting attack and crevice attack are encountered in this solution, within 72 hours. It should be noted that HYBRID-BC1 alloy exhibits a respectable uniform corrosion rate of approximately 0.5 mm/y (20 mpy) at 120°C in this solution, whereas B-3 corrodes at 47.69 mm/y (1,878 mpy) under the same conditions. While 120°C is the maximum temperature of HYBRID-BC1® alloy in acidifi ed 6% FeCl3, the fact that the material can withstand such a strongly oxidizing medium to the 120°C, yet provide such high resistance to the key reducing acids, is remarkable.

Alloy Critical Crevice Temperature Critical Pitting Temperature
- °F °C °F °C
HYBRID-BC1® 257 125 >284 >140
C-4 122 50 212 100
C-22® 176 80 >284 >140
C-276 131 55 >284 >140
C-2000® 176 80 >284 >140
316L 32 0 59 15
254SMO® 86 30 140 60
625 104 40 212 100
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