ContentsClassification ofSuperalloysPropertiesApplicationsApplication in Oil-Gas sector Turbine blades made up of nickel superalloy
Classification of Superalloys• These alloys have austenitic FCC structure which have base alloying element of nickel, cobalt and iron.• Further they are classified on the basis of pre- dominant element present in it.• Alloying elements are Fe, Co, Ni, Cr, W (tungsten), Mo (molybdenum), Nb (niobium) and Ta (tantalum).• Iron based alloys:(a) 9-38 % nickel(b) 15-22 % chromium(c) 32-67 % ironCommon type of Iron based alloy is Incoloyseries.
• Cobalt based alloys:(a) Up to 35% nickel(b) 19-30 % chromium(c) 30-65 % cobaltCobalt based alloys can retain their strength athigh temperature but they are not as strong asnickel based alloys.
• Nickel based alloys:(a) 38-76% nickel(b) Up to 27 % chromium(c) Up to 20 % cobalt.Some of the common type of nickel based alloysare Nimonic, Hastelloy and Inconel.These are the most common types ofSuperalloy which are widely used in turbineblades
Properties of Superalloys• Excellent mechanical strength and wear resistance at high temperature.• Resistance to corrosion and oxidation at very high temperature.• Good surface stability.
Applications of Superalloys• In Aerospace : blades of turbines and in jet/rocket engines.• In Marine : wide use in Submarines.• In Chemical processing industries.• Heat exchanger tubing• Industrial gas turbines• Nuclear Reactors