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Corrosion Resistance of Welds

To assess the resistance of welds to corrosion, Haynes International has chosen to test all-weld-metal samples, taken from the quadrants of cruciform assemblies, created using multiple gas metal arc (MIG) weld passes. Predictably, the inhomogeneous nature of weld microstructures leads to higher corrosion rates (than with homogeneous, wrought products). Nevertheless, HASTELLOY® C-22® alloy exhibits excellent resistance to the key, inorganic acids, even in welded form, as shown in the following table:

Chemical Concentration Temperature Corrosion Rate
wt.% °F °C Weld Metal Wrought Base Metal
mpy mm/y mpy mm/y
H2SO4 30 150 66 0.6 0.02 0.4 0.01
H2SO4 50 150 66 9.3 0.24 0.8 0.02
H2SO4 70 150 66 10.3 0.26 11.0 0.28
H2SO4 90 150 66 18.5 0.47 13.4 0.34
HCl 5 100 38 <0.1 <0.01 <0.1 <0.01
HCl 10 100 38 <0.1 <0.01 0.4 0.01
HCl 15 100 38 11.1 0.28 9.4 0.24
HCl 20 100 38 10.2 0.26 7.9 0.20
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