Applications of Superalloys

Alireza S. AkbariInstitut für Metallkunde und Metallphysik

RWTH Aachen

Seminar II – SS 07

Contents

General background on development of superalloys

Iron base superalloys (characteristics – applications)

Cobalt base superalloys (characteristics – applications)

Stellites (applications)

Nickel base superalloys (general classification –

characteristics)

Introduction to selected Ni-base superalloys (Inconel –

Hastelloy – Monel)

Some notes on superalloys

Development of superalloys since 1940 working temperature: 600°C –

1150°C resistance against high mechanical loads high oxidation and corrosion resistance

increase of high-temperature applicability

Forging

Investment Casting Directional

Solidification

Single Crystal Solidification

Application based on matrix material

FeOxidation resistance by Cr addition

High and room temp. strength

Creep, oxidation, corrosion and wear resistance

Application in turbine discs

e.g. Incoloy

Application based on matrix material

Co Ni, Cr and W as further alloying elements

Haynes 167

Combustion chambers

Nuclear reactors

Wear resistant materials

Application based on matrix material

Co Ni, Cr and W as further alloying elements

Haynes 167

Stellite 6B

Stellite 6B

handling extreme conditions of wear, abrasion, and heat

high hardness at high temps.

recovers full hardness after exposure to temps. up to 1100°C

excellent resistance to oxidation, corrosion and thermal shock

Applications

erosion shielding in steam turbines resistant top coats in gas turbines pipe elbow guiding in hot particles

at high temps.

Application based on matrix material

Ni th

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group o

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uperallo

ys

Ni-base superalloys

WROUGHT DS/SX PM/ODS

Astroloy

Hastelloy X

Inconel 718

Nimonic

Udimet 500

Rene N4 MA 6000

General Applications

Load bearing

structures at

high ThomGas turbines

Rocket engines

Submarines

Nuclear reactors

Chemical processing

vessels

Heat exchanger

tubing

Ni-base superalloysintroduction to selected alloy series

Inconel alloys

high oxidation resistance

ability to maintain their structural integrity in high temperature atmosphere resistance against caustic corrosion

resistance against corrosion caused by high purity water

resistance against stress-corrosion cracking

General remarks

Major application:

CHEMICAL INDUSTRY

Inconel 738

precipitation-hardenable

nickel-chromium alloy

Fe, Mo and Nb additions,Ti and Al

(trace elements)

good weldability

resistant to post-weld cracking

maintain its structure in both high-

temperature and aqueous environments superb creep-rupture strength at

temperatures as high as 700°C

Applications

Spacecrafts

Nuclear reactors

Rocket motors

Ni-base superalloys

introduction to selected alloy series

Hastelloys

General remarks

one of the best corrosion resistants

(among Ni-base S.A.)

high resistance in chemical and

oxidizing applications

one of the world's toughest materials

pitting and cracking resistant

high-temperature strength in vacuums and atmospheres that are chemically inert

Hastelloy X

one of the world's most popular alloys uncommon resistance to oxidation exceptional heat resistance and

fabricability

good ductility

good price

Applications

gas turbine engines

flame holders industrial furnaces

Rotary Dryer

Ni-base superalloys

introduction to selected alloy series

Monel

General remarks

developed by Robert Crooks Stanley who worked for the International Nickel Company (INCO) in 1901

The new alloy was named in honor of the president of the company, Ambrose Monell is based on nickel (65-70%) and copper (20- 29%) and also contains iron and manganese (5%) and other compounds Standard product forms are round, hexagon, flats, forging stock, pipe, tube, plate, sheet, strip, and wire

stronger than steel

malleable

low coefficient of thermal expansion

highly resistant to alkalis

able to be welded,

brazed and soldered

Applications

Pump shafts

Impellers

Blades and scrapers

oil-well drill instruments

springs

Valve trim

Propeller

valve

components

for ships

centrifugal pumps

in the

marine industrykitchen

sinks

frames of eyeglasses

Golf

Some notes…

Superalloys or high-performance alloys, are the materials able to withstand extreme temperatures that would destroy conventional metals like steel and aluminum The widespread use of superalloys in turbine engines

coupled with the fact that the thermodynamic efficiency of turbine engines is increased with increasing turbine inlet temperatures

To avoid surface attack (due to the presence of reactive alloying elements) including oxidation, hot corrosion, and thermal fatigue,in the most demanding applications, such as turbine blade and vanes, superalloys are often coated to improve environmental resistance.

and…..

having a quick look into the wide range having a quick look into the wide range ofof

superalloys’ applications, shows that superalloys’ applications, shows that these materials have been affecting the these materials have been affecting the

human life, from within the human body to human life, from within the human body to the spacecrafts, and from power the spacecrafts, and from power

generation plants to almost any field which generation plants to almost any field which may need a stable, strong and may need a stable, strong and

environmentally resistant material, for half environmentally resistant material, for half a century!!a century!!

THANK YOU!