Abstract
The hot corrosion behavior of a series of wrought nickel-base superalloys containing approximately 13 wt pct Cr was studied as a function of molybdenum content from 0 to 8 wt pct Mo in each of four Al + Ti levels (3 pct Al, 41/2 pet Al, 6 pct Al, and 1 pct Al-31/2 pct Ti). Specimens were tested in a burner rig with a 5 ppm sea salt concentration in a 1 pct sulfur diesel fuel burned at a 30:1 air-to-fuel ratio and were cycled between 1600°F (870°C) or 1800°F (980°C) and room temperature every 50 h during a 1000-h test. It was found that molybdenum significantly reduced the amount of hot corrosion attack at 1600°F (870°C) for the three aluminum-containing series of alloys. For the titanium-containing series of alloys tested at 1600°F (870°C) and all alloys exposed at 1800°F (980°C), molybdenum exerted little influence on hot corrosion behavior. Aluminum was found to markedly increase sulfidation rates at both 1600°F (870°C) and 1800°F (980°C) for all molybdenum levels. Titanium appeared to be beneficial to the hot corrosion resistance of these alloys at 1600°F (870°C) and detrimental at 1800°F (980°C). It was further noted that 1600°F (870°C) represented a more severe sulfidation condition than 1800°F (980°C) under these test conditions.
Published Version
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