Cold Work and the General Corrosion of
Ni-Mo and Ni-Cr-Mo Alloys. Figures 4 and 5
show the effect of CW on the general corrosion
behavior of nickel alloys. Figure 4 shows that
the corrosion rate of N10665 (Hastelloy B-2) in
boiling 20% HCl is approximately 0.34 mm/year
(13 to 14 mils/year) and does not change in the
range of CW between 0 and 50%. In this same
range of CW, the hardness of alloy B-2 increases
from 90 HRB to more than 40 HRC (Fig. 4).
A boiling solution of HCl would be reducing
and therefore promote a general or uniform corrosion
rate in a nickel-molybdenum alloy such
as B-2 (Table 2). Figure 5 shows that the corrosion
rate of N06455 (Hastelloy C-4) in boiling
10% HCl is approximately 6 to 7 mm/year
(250 to 275 mils/year) and does not change in
the range of CW between 0 and 50%. Because a Ni-Cr-Mo alloy has a lower amount of molybdenum
than a nickel-molybdenum alloy, the corrosion
rate of Ni-Cr-Mo alloys in boiling HCl
solutions is generally higher than the corrosion
rate of nickel-molybdenum alloys in similar solutions
(Ref 36). Figure 5 also shows that the corrosion
rate of C-4 in ASTM G28Method A solution
is approximately 3.56 mm/year (140 mils/year)
and does not change with the amount of CW
between 0 and 50%. For both reducing, 10%
HCl, and oxidizing, ASTM G28 Method A, solutions,
the general corrosion rate does not change
as the amount of CW is increased in the alloy.
Results from Fig. 5 suggest that the higher presence
of dislocations in a CW microstructure does
not affect considerably the hydrogen evolution
reaction under reducing conditions or the passivation
characteristics under oxidizing conditions
for nickel alloys.
Cold Work and the General Corrosion ofNi-Mo and Ni-Cr-Mo Alloys. Figures 4 and 5show the effect of CW on the general corrosionbehavior of nickel alloys. Figure 4 shows thatthe corrosion rate of N10665 (Hastelloy B-2) inboiling 20% HCl is approximately 0.34 mm/year(13 to 14 mils/year) and does not change in therange of CW between 0 and 50%. In this samerange of CW, the hardness of alloy B-2 increasesfrom 90 HRB to more than 40 HRC (Fig. 4).A boiling solution of HCl would be reducingand therefore promote a general or uniform corrosionrate in a nickel-molybdenum alloy suchas B-2 (Table 2). Figure 5 shows that the corrosionrate of N06455 (Hastelloy C-4) in boiling10% HCl is approximately 6 to 7 mm/year(250 to 275 mils/year) and does not change inthe range of CW between 0 and 50%. Because a Ni-Cr-Mo alloy has a lower amount of molybdenumthan a nickel-molybdenum alloy, the corrosionrate of Ni-Cr-Mo alloys in boiling HClsolutions is generally higher than the corrosionrate of nickel-molybdenum alloys in similar solutions(Ref 36). Figure 5 also shows that the corrosionrate of C-4 in ASTM G28Method A solutionis approximately 3.56 mm/year (140 mils/year)and does not change with the amount of CWbetween 0 and 50%. For both reducing, 10%HCl, and oxidizing, ASTM G28 Method A, solutions,the general corrosion rate does not changeas the amount of CW is increased in the alloy.Results from Fig. 5 suggest that the higher presenceof dislocations in a CW microstructure doesnot affect considerably the hydrogen evolutionreaction under reducing conditions or the passivationcharacteristics under oxidizing conditionsfor nickel alloys.
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