lecture 6 -nickel and its alloys - suranaree university of...

Suranaree University of Technology May-Aug 2007

Nickel and its alloysNickel and its alloys

Subjects of interest

• Objectives/Introduction

• Production of nickel and nickel alloys

• Commercially pure nickel

• Nickel-copper alloys (Monels)

• Nickel-chromium alloys

• Nickel-base superalloys

• Single crystal castings of nickel-base

superalloys

Lecture 6

Tapany Udomphol


ObjectivesObjectives

• This chapter provides fundamental knowledge of

different methods of productions of nickel alloys and the

use of various types of nickel alloys.

• The influences of alloy composition and microstructure

on chemical and mechanical properties of nickel alloys will

be discussed in relation to its applications.

Tapany Udomphol


IntroductionIntroduction

Properties

• Silvery shiny appearance

• High toughness and ductility

• Good high and low

temperature strength

• High oxidation resistance

• Good corrosion resistance

• Ferro-magnetic

• Relatively high cost

• Not mixed with cheap

alloying elements.

Limitations

Nickel

Ni

Crystal structure FCC

Atomic number 28

Atomic weight 58.71

Density (g.cm-3) 8.89

Melting point (oC) 1455

28

58.71

FCC

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ApplicationsApplications

• Applications required necessary corrosion or heat- resisting

properties and for special engineering applications.

• Chemical plant, heat exchanger, reaction furnace, rotary kiln,

turbine blades.

• Used as alloying elements in stainless steels, and in other

elements such as copper, cobalt, chromium, etc.

Aerospace flow bodies

www.immnet.com

Turbine blades

www.msm.cam.ac.uk

Heat exchangersReaction furnace

Rotary kiln

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Production of nickelProduction of nickel

www.mii.org

First discovery of nickel mineral by the German was

mistakenly misunderstood to be rich-copper mineral.

There are three major types of nickel deposits (sources):

1) Nickel-copper sulphide

2) Nickel silicates

3) Nickel laterites and serpentines

Nickel laterite deposits

research.eas.ualberta.ca/ egg/nilaterite.jpg Nickeline or niccolite

Serpentine deposits

home.arcor.de

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Extraction of nickelExtraction of nickel

Nickel-sulphide ore

(Fe, Cu)

Crushing

Grinding

Magnetic separation

Iron sulphide

(pyrrhotite

concentrate)

Iron ore

recovery plant

Froth flotation treatment

Nickel concentrate Copper concentrate

Remaining ore

(Ni, Cu)

Copper

smelter

Roasting

Smelting(Reverberatory furnace)

Bessemer matte

(Ni and Cu sulphides)

Recrystallisation

Cooling

Crushing & grinding

Crystals of Ni and Cu

sulphides.

Ni-Cu metallic alloy

Froth flotation

Copper sulphide Nickel sulphide

Different grade

of nickel oxides

Roasting

Nickel refinery

Pure nickel and

other nickel alloy

products

Suranaree University of Technology May-Aug 2007Tapany Udomphol


Classification of nickel alloysClassification of nickel alloys

There are different types of nickel and nickel alloys;

1) Commercially pure nickel

2) Nickel-copper alloys (Monels)

3) Nickel-chromium alloys

4) Nickel-base superalloys

5) Nickel-iron superalloys

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Commercially pure nickelCommercially pure nickel

• High purity nickel contains 99.99% Ni.

• Commercially pure nickel contains

99.5% Ni (+Co).

• Microstructure consists of solid solution

phase in annealed condition.

Cold drawn Nickel 200 annealed

at 829oC

Properties

• Good mechanical properties

and retains its strength at

elevated temperature.

• Excellent resistance to most

corrosive environment.

Applications

• Food processing equipment

• Electrical & electronic parts

• Caustic handling equipment.

100 x

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NickelNickel--copper alloys (copper alloys (MonelsMonels))

• Ni and Cu form complete solid solution.

• Most important Ni-Cu alloy contains

67%Ni and 33%Cu, called Monels.

Properties

Applications

• High strength and toughness over

a range of temperature.

• Good weldability

• Excellent corrosion resistance

Microstructure of

cold drawn Monel

R405 and

annealed at 829oC,

showing solid

solution phase of

Ni-Cu with

sulphide stringers

(black)

• Values, pumps, marine fixtures

and fasteners.

• Chemical processing equipment.

• Oil-well drill collars and

instruments.

Ni-Cu phase diagram

250 xTapany Udomphol


NickelNickel--chromium alloyschromium alloys

• Cr forms solid solution with Ni up to~30%

at RT. High corrosion resistance is due to

high Cr addition.

• Inconel 600 (15.5%Cr, 8%Fe) is a

standard engineering alloy. Other Ni-Cr

alloys are Inconel 601 and 625 with

improved properties.

Ni-Cr phase diagram

Properties

Applications

• High corrosion resistance at

high temperature.

• High strength and workability.

• Heat exchanger tubing

• Chemical and food

processing equipment.

• Furnace muffle.

Inconel 600, solution

heat-treated at

1200oC/1h+870oC/4h,

showing solid solution

phase with chromium

carbide precipitates at

GBs and some titanium

carbides and nitrides

within the grains1500 x

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NickelNickel--base base superalloyssuperalloys

• High temperature heat-resistance alloys, which can retain

high strengths at elevated temperatures.

Properties

Applications

• Heat resistant and high strength at high

temperature (760-980oC).

• Good corrosion resistance.

• Good oxidation resistance.

• There are three types of Ni-base superalloys; nickel base, nickel-

iron base and cobalt base. The alloys contain high Cr with Ti, Al to

from precipitates and additions of Mo, Co, Nb, Zr, B, Fe.

• Microstructures are complex.

• Aircrafts, space vehicles, rocket engines

• Industrial gas turbines, high temp applications.

• Nuclear reactors, submarines.

• Steam power plants, petrochemical equipment.

www.stratcor.com

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Microstructure of nickel base Microstructure of nickel base superalloyssuperalloys

The major phases present in the nickel-base superalloys:

1)1)1)1) γγγγ (gamma) phase – the continuous matrix of FCC austenite.

2)2)2)2) γγγγ’ (gamma prime) phase – the major precipitate phase (more cubic shape).

3) Carbides –various types, mainly M23C6 and MC. M = metal.

Complex microstructure of astroloy

forging after heat treatments

10,000 x

Carbides

at GB

Note: GB carbides affect high-temp strength, ductility, creep.

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NickelNickel-- iron iron superalloyssuperalloys

• Fe is added to replace some of Ni as it has lower cost.� lowering

the properties as compared with nickel base superalloy. �

therefore it is used at lower temperatures.

• Ni-Fe superalloys contains 25-45%Ni and 15-60%Fe.

• Higher Ni content increases operating temp (upto 815oC), due to

improved stability but more costly.

• Ex: Inconel 707, 718, 901.

• Microstructure consists of

austenistic FCC matrix and can

be strengthened by solid solution

strengthening (Mo, Cr), and

precipitation hardening (Ti, Nb, Al)

by forming intermetallic phases. 15,000 x

Optical micrograph of

Inconel 901 after

precipitation hardening

SEM micrograph of Inconel 718

after exposure at 705oC/6,048

h, 37 ksi

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SingleSingle--crystal castings of crystal castings of

nickelnickel--base base superalloyssuperalloys

• A major increase in strength and temperature capability of

superalloy casting has been much improve with the introduction of

columnar-grained and single crystal casting.

Diagram of setup

for single crystal

casting

www.nap.edu

Simulation of

evolution of grain

structure in a single

crystal casting.

Turbines blades are

cast using a spiral

starter

Competitive

grain

www.msm.cam.ac.uk

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Applications of singleApplications of single--crystal castings of crystal castings of

nickelnickel--base base superalloyssuperalloys

• Used in production of aerofoils, gas turbine engines,

which allow the operating temperature range ~ 50oC higher

than normal materials.

Single crystal casting

of superalloy

www.grc.nasa.gov

Property

comparison

between

polycrystal,

columnar

crystal and

single crystal

(a) Polycrystal (b) Columnar

crystal

(c) Single

crystal

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ReferencesReferences

• �� , � ��กก �� ก, 2536, ��ก�� ก�� !" �", ISBN

974-582-155-1.

• Smith, W.F., Structure and properties of engineering

alloys, second edition, 1993, McGraw-Hill, ISB 0-07-59172-5.

• www.cda.org.uk.

• Heußner, U., Nickel alloys, 1998, Marcel Dekker, Inc., ISBN

0-8247-0440-1.

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lecture 6 -nickel and its alloys - suranaree university of...

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