superalloy slides

METE 327 Physical Metallurgy Copyright 2008 Loren A. Jacobson 5/16/08

SUPERALLOYS

METE 327Fall, 2008


OUTLINE Historical perspective Applications Compositions Processes Properties

− Creep


Applications Gas Turbine Engines

− Blades, vanes, disks, combustors Space Vehicles

− Rocket motors Nuclear Reactors Submarines Petroleum Equipment


Compositions Ni, Co and Fe Based Alloys Solid solution strengthening

− Cr, Mo, Al, Nb, Ti and others Precipitation strengthening

− Mostly due to Al and Ti− Ni3(Al,Ti), gamma prime− Lattice mismatch, amount, size and morphology

Carbide phases− M23C6, M6C or MC− M can be Cr, Ti, Mo or W


Astroloy Microstructure (orig. 15 K X)


CREEP Deformation at high temperature under

constant load Important property of Superalloys Brief discussion now, more next time


Engineering Design Using Creep (and Stress-Rupture)

The Larson-Miller Parameter:

Stress Rupture Data Plottedaccording to the followingequation:

Where M = log e

and θ = t exp (-Q/RT)

assuming that Q and θ are functions of stress only. t can be atime to rupture or a time to a given creep strain.

Engineering Design Using Creep (and Stress-Rupture)

The Larson-Miller Parameter:

Stress Rupture Data Plottedaccording to the followingequation:

Where M = log e

and θ = t exp (-Q/RT)

assuming that Q and θ are functions of stress only. t can be atime to rupture or a time to a given creep strain.


Assignment Please email me a question about superalloys

before Monday, 17 November [email protected] More about creep next time, and Materials

Selection for Design

mailto:[email protected]

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