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HAYNES® Alloys

Sulfidation Resistance

HAYNES® 188 alloy has very good resistance to gaseous sulfidation envronments encountered in various industrial applications. Tests were conducted at 1400°F (760°C) in a gas mixture consisting of 5 percent H2, 5 percent CO1, 1 percent CO2 , and 0.15 percent H2S, balance Ar. Coupons were exposed for 215 hours. This is a severe test, with equilibrium sulfur partial pressure of 10-6 to 10-7 and oxygen partial pressures less than that needed to produce protective chromium oxide scales.

Sulfidation Resistance at 1400°F (760°C)

188 - SULFIDATION RESISTANCE

215 hours in an atmosphere of 5% H2 + 5% CO + 0.15% H2S + Balance Ar
Alloy 1400°F (760°C) 1600°F (871°C)
Metal Loss Average Metal Affected Metal Loss Average Metal Affected
mils μm mils μm mils μm mils μm
25 0.5 13 1.5 38 1.1 28 5.3 135
188 1.6 41 3.3 84 1.7 44 5.7 145
556® 3.1 77 4.9 124 6.2 157 16.4 417
310 6.2 157 9.1 231 8.3 211 14.1 358
617 5.0 127 10.8 274 3.8 97 17.2 437
800H 7.1 180 11.2 284 7.9 201 >27.6 >701
625 6.6 168 12.6 320 Partially Consumed
X - - >29.5 >749 - - >21.7 >551

Schematic Representation of Metallographic Technique
Used for Evaluating Environmental Tests

188 Sulfidation

Water Vapor Oxidation Data

Air + 20% H2O at 1800°F (982°C), 1008 hours, cycled weekly
Alloy Metal Loss Average Metal Affected
mils μm mils μm
214® 0.04 1 0.64 16
230® 0.19 5 1.59 40
625 0.36 9 1.66 42
188 0.18  5  1.48 38
X 0.27 7 1.77 45
617 0.39 10 1.99 50
556® 0.35 9 1.85 47
HR‐120® 0.38 10 2.08 53
800HT 2.47 63 5.07 129
HR‐160® 0.77 20 5.57 141
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