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HAYNES® Alloys

Oxidation Resistance

MULTIMET® exhibits acceptable oxidation resistance up to around 1800°F.  However, due to concerns with oxidation resistance, MULTIMET® has been generally replaced by 556® alloy, which has comparable creep-rupture strength but superior oxidation resistance, particularly at temperatures greater than 1800°F.  

Short-term Oxidation

Comparative Oxidation Resistance in Flowing Air, 1008 Hours

Alloy 1800°F (980°C) 2000°F (1095°C)
Metal Loss Average Metal Affected Metal Loss Average Metal Affected
mils μm mils μm mils μm mils μm
MULTIMET® 0.4 10 1.3 33 8.9 226 14.3 363
556® 0.4 10 2.3 58 1.5 38 6.9 175

Flowing air at a velocity of 7.0 ft/min (213.4 cm/min) past the samples.  Samples cycled to room temperature once per week.

 Dynamic Oxidation Burner Rig

Alloy 1600°F (870°C), 1000 h, 30-min cycles 1600°F (870°C), 2000 h, 30-min cycles
Metal Loss Average Metal Affected Metal Loss Average Metal Affected
mils μm mils μm mils μm mils μm
MULTIMET® 1.3 33 2.2 56 2.7 69 4.9 124
556® 1.4 36 3.1 79 1.5 38 3.9 99

Burner rig oxidation tests were conducted by exposing sampIes 3/8 in. x 2.5 in. x thickness (9 mm x 64 mm x thickness), in a rotating holder, to products of combustion of No. 2 fuel oil burned at a ratio of air to fuel of about 50:1. (Gas velocity was about 0.3 mach). Samples were automatically removed from the gas stream every 30 minutes and fan-cooled to near ambient temperature and then reinserted into the flame tunnel.

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