Superalloys

Properties and Applications

ContentsClassification of SuperalloysProperties ApplicationsApplication 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 Incoloy series.

• Cobalt based alloys:(a) Up to 35% nickel(b) 19-30 % chromium(c) 30-65 % cobaltCobalt based alloys can retain their strength at high temperature but they are not as strong as nickel 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 of Superalloy which are widely used in turbine blades

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

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