lesson 4 2014. selection of metallic materials (other metallic materials than steels)

BK50A2700 Selection Criteria of Structural Materials

Lesson 42014

Selection of metallic materials (other metallic materials than steels)

Other metallic

materials than steels

Aluminum alloys

Magnesium alloys

Zinc alloys

Copper alloys

Nickel alloys

Titanium alloys

STEELS

- Caebon steels

- QT-steels- Carburizing steels- Stainless steels- etc.

Metallic materials

REMEMBERTO WIDEN

THE SELECTION AREA…

Aluminum alloys

Aluminum alloys in general

Small density

Relatively good

corrosion resistance

Limited strength

and stiffness

propertiesGood

electrical conductivi

ty

Good heat conductivi

ty

Easy formabilit

y

Disadvantage

Moderate

Advantage


Small density

Aluminum’s density is about1/3 of steel’s density

BUT

Aluminum’s modulus of elasticityis also about 1/3 of steel’s modulusof elasticity

THEREFORE

It is not so self-evident how muchlighter the aluminum constructionmight be…

IN GENERAL

The equal strength and stiffnessproperties are achieved with an aluminum structure which is only about 50 % lighter that the corresponding steel structure.

Steel Aluminum

Disadvantage

Moderate

Advantage


Relatively good


Disadvantage

Moderate

Advantage

Depends on the affecting chemicalenvironment- acidic

alkaline- pH-value- mediums- Temperature- sea water- etc.

Depends on the alloying of the selected aluminum:- Copper- Magnesium

Corrosion resistance of aluminum alloysIn general the oxide layer protects the

base material (5-10nm)The corrosion resistance can be

improved by utilizing anodizing (electrolytic passivation process)

Copper alloying decreases remarkably aluminum’s corrosion resistance

In water and seawater aluminum alloys may suffer from localized corrosion

Better corrosion resistance in seawater can be achieved by magnesium alloyed aluminums

The oxide layer is able to protect aluminum’s surface only between the pH-range of 4…8.5

Corr

osi

on

sp

eed

Acidic Neutral Alkaline


Very corrosive:- Lye- Sodium sulfide- Hydrochloric acid- Hydrofluoric acid- Sulfuric acid- Chlorine- Phosphoric acid

Low or non-corrosive:- Boric acid- Arsenic acid- Carbonic acid- Formic acid (if T < 50° C)- Phenol (if T < 120 °C)- Most of alcohols- Benzene,

Toluene- Naphthalene- Styrene- Oxygen- Hydrogen- Nitrogen- Helium- Argon- Carbon

monoxide- Carbon dioxide


Limited strength

and stiffness

properties

Disadvantage

Moderate

Advantage

Aluminum’s melting point is only 658°C and low creeping strength might become a problem not higher than at > 100°C.

Aluminum’s fatigue strength is 0.35…0.55×RM.

Note that aluminum’s fatigue strength is usually expressed based on not more than 3-5×108 loading cycles.

Note that aluminum products, which are made by casting suffer from even lower fatigue strength than products, which are made by forming.

Under corrosive environmental loading aluminum’s fatigue strength decreases dramatically.

At low temperatures aluminum’s strength values are higher than at room temperature and its ductility remains constant. Therefore aluminum alloys are used in cryogenics (e.g. vessels for liquid gases, under - 160°C.


Good electrical conductivi

ty

Good heat conductivi

ty

Disadvantage

Moderate

AdvantageAluminum’s thermal conductivity is three times better compared with steels and cast irons. This property is utilized e.g. in electromechanical industry.

Aluminum has good electrical conductivity and compared with copper, the weight of the wire made of aluminum, is only 50% of the weight of the wire made of copper.

Alloying affects greatly both the electrical and thermal conductivity.


Easy formabilit

y

Disadvantage

Moderate

Advantage

Different types of standardized aluminum profiles are available.

Due to aluminum’s easy formability customized profiles can easily be manufactured by extrusion.

Profiles and plates can be coated for several purposes.

Especially good formability can be achieved with magnesium and silicon alloyed aluminums.

1000-seriesPure

aluminumElectrical

conductivity(other alloys 8000-

series)

3000-series

Aluminum with

manganese alloying

4000-series

Aluminum with

silicon alloying

5000-series

Aluminum with

magnesium alloying

6000-series

Aluminum with

magnesium and silicon

alloying

7000-series

Aluminum with zinc alloying

2000-series

Aluminum with

copper alloying

High corrosion resistancein seawaterNo heat treatments availableEN-AW-5754

Good suitability for anodizingSuitable for heat treatmentsEN-AW-6082 The mostly used grade in mechanical engineeringEM-AW-6063 Aluminum profiles, tubes

High strengthbut poor weldability Suitable for heat treatmentsEN-AW-7050 AirplanesEN-AW-7075 Airplanes

Moderate weldability, corrosion resistanceand good formabilityNo heat treatments availableEN-AW-3103 Car bodiesImproved ductility and

machinabilityRisk of corrosionSuitable for heat treatmentsEN-AW-2007 Excellent for turning

Suitable for casting and powder metallurgy

Selection of the best

aluminum alloy for the

product

PAY SPECIALATTENTION TO CLARIFY

THE FOLLOWINGREQUIREMENTS:1. Corrosive

environment2. Temperature

and acidic/alcaline ranges

3. Possible dynamic loading

4. Intended manufacturing

methods in production

REQUIREMENTSPROFILE

COMPARISONOF MATERIALPROPERTIES

COMPARECAREFULLY AVAILABLEDIFFERENTOPTIONS:

1) 1000…8000 series (optimum alloying)2) Heat treatments (if possible)3) Anodizing4) Standardized profiles and other bulk materials

SFS-EN 515 Aluminum and aluminum alloys. Temper designations.

SFS-EN 573-1…5 Aluminum and aluminum alloys. Chemical composition, numerical designation system, forms of products and codification of standardized products.

Remember, that it is important to recyclealuminum!

The manufacturing process ,which utilizes recycled aluminum needs only 5% of that energy amount required in the process starting from ore (bauxite).

About 75% of aluminum is recycled nowadays.

Copper and copper alloys

Brasses

Bronzes

Nickel Silver

Tough pitch

copper

Deoxidized

copper

Oxygen-free

copper

Pure copper and copper

alloys

Pure copper

Copper alloys

Grades of pure copper High electrical conductivity

Cu-OF (oxygen-free copper) Copper amount at least 99,95 %

Extremely hight electrical conductivity Cu-OFE (oxygen-free copper, electronic grade Copper amount at least 99,99 %.

The most common copper grade : Cu-ETP (tough pitch copper)

Coppers for general use are usually deoxidized grades : Cu-DHP (phosphorus-deoxidized copper – high residual

phosphorus) Cu-DLP (phosphorus-deoxidized copper – low residual

phosphorus

Copper alloysCopper alloys contain at last 2.5% alloying components:

BRASSES BRONZES NICKEL SILVER

Zinc alloys (different grades of brasses)

Tin, lead, nickel and zinc (different grades of tin-bronzes)

Aluminum (different grades of aluminum-bronzes)Beryllium (different grades of beryllium-bronzes)Silicon (different grades of silicon-bronzes)

Nickel and zinc (different grades of nickel silver)Nickel-Copper alloys


alloys in general

Some special

properties available

Moderate strength

properties

Poor weldabilit

y

Relatively good


Good electrical

and thermal

conductivity

Easy formabilit

y, machinabili

ty and castability

Disadvantage

Moderate

Advantage

Pure copper

Good electrical

and thermal

conductivity

Disadvantage

Moderate

Advantage

High electrical conductivity:

Cu-OF (oxygen-free copper)

Extremely high electrical conductivity:

Cu-OFE (oxygen-free copper, electronic grade)


alloys in general

Easy formabilit

y, machinabili

ty and castability

Disadvantage

Moderate

Advantage

Unlike usually known chemachinability properties of copper alloys, especially many brasses, are excellent.

Maybe this is because pure copper is difficult for machining.

Copper alloys have excellentformability properties both for cold and hot forming.

By using suitable alloying copper alloys havegood castability properties


alloys in general

Some special

properties available

Disadvantage

Moderate

Advantage

Copper-Beryllium alloys have excellent wear resistance. However, they have poor machinability and weldability properties.

Copper alloys have good resistance against the growth of microbes.

Copper alloys are non-magnetic metallic materials.


alloys in general

Relatively good


Disadvantage

Moderate

AdvantageGood corrosion resistance infreshwater seawater,steam soilclimatic conditions

corrosion rate 0-2,2 µm/year

In sulphuric conditions corrosion resistance is poor

Typical corrosion types are:

Erosion - Flow rates in tubes and

pipelines should be limited

Selective corrosion - Dezincification of

brassesStress corrosion - Especially brasses

suffer from stress corrosion

- Nitrides and ammonia increase the risk

Because copper is a relatively noble metal, it can cause the reaction of galvanic corrosion with the adjacent materials


alloys in general

Moderate strength

properties

Disadvantage

Moderate

Advantage

Modulus of elasticity, 0.2-limit, ultimate tensile strength and elongation to fracture increase when the temperature decreases.

Ductility increases when the temperature decreases.

Ultimate tensile strength and 0.2-limit decrease when temperature increases.

Creeping strength becomes critical already at 100-200°C depending in the alloying.

Fatigue strength difficult to establish, endurance limit describes the stress to cause the fracture at certain number of loading cycles (100×106).

Typically the endurance limit is only about 1/3 of RM

Strength is highly depending on the alloying, temper designation and manufacturing process .


alloys in general

Poor weldabilit

y

Disadvantage

Moderate

AdvantagePoor weldability

porosity of seams decreased strength Decreased ductility Strict requirements of

cleanness

StandardizationSFS-ISO 1190-1. Copper and copper alloys Chemical

composition and designation.SFS-EN 1173. Copper and copper alloys. Temper

designations.SFS-EN 1412. Copper and copper alloys. Numerical

designation system.

Examples:Cu-OF-04 CuZn39Pb2 GZ-CuPb10Sn

Some application areas of copper:Constructions where climatic loading is

affectingWater piping lines Seawater applicationsHeat exchangersSteam power plant applicationsElectrical industry

Nuclear fuel waste management

Property Result of comparison

Yeld strength The yeld strength of steels is 2.5…10 times higher.

Fatigue strength The fatigue strength of steels is 2…6 times higher.

Hardness The maximum hardness of steels is about 2 times higher. The hardness of some CuBe-alloys might be equal or higher

Elongation to fracture

Copper alloys have (in average) 1.5 times higher elongation.

Modulus of elasticity

The modulus of elasticity of steels is 1.5…3 times higher.

Comparison of steels and copper alloys

One example of selecting the optimal copper grade:The power feeding strip of a smart

antenna application should meet the following requirements:

High priority (demands):Excellent electrical performance to avoid

power losses Good environmental corrosion resistance in

different types of climate conditionsLower priority (wishes)

Acceptable weldability with the radiating elements and feeding pins

Ability to function as springs to ensure good electrical contact and easy assembly

RADOME RADIATING ELEMENTS

POWER FEEDING PINS

GROUND PLANE

POWER FEEDING STRIPS

BODY MADE OF FOUR-CORNERED BARS

REAR PLATE

N-TYPE CONNECTORS

HOUSING OF ELECTRONICS

JOINING COMPONENTS OF THE SMART ANTENNA

Deoxicidized Cu-DHPModerate electrical conductivityAcceptable weldabilityPerformance about 70% of themaximum

Copper-Tin alloy CuSn6Moderate electrical conductivityGood corrosion resistanceModerate weldabilityProperty to function as a spring is possible Performance only about 10% of the maximum

Oxygen free Cu-OFBest electrical conductivityMaximum performance

Selection of the best

copper alloy for the

product

REQUIREMENTSPROFILE


Electricalconductivity

Thermal Conductivity

CorrosionResistance

EasyFormability

Easy Machinability

EasyCastabilityCorrosionresistance

PURECOPPERSOxygen

freecoppers

PURECOPPERS

deoxidized coppers

BRASSESBRONZES

OTHERCOPPERALLOYS

Wires

Piping

ComponentsMachine parts

SFS-ISO 1190-1. Copper and copper alloys Chemical composition and designation.

SFS-EN 1173. Copper and copper alloys. Temper designations.

SFS-EN 1412. Copper and copper alloys. Numerical designation system.

Titanium alloys

Different grades of titanium

alloys

ASTM Grades 2 and 3

ASTM Grade 1

ASTM

Grade 4

ASTM Grade 5

ASTM Grades 7 and 8

Other grades

Most important alloys:

Some typical application areas: Gr 1: Good formability e.g. for stretch forming or deep

drawing. Gr 2 ja 3: Grades for many applications in chemical process

industrial and mechanical engineering Gr 4: High hardness, which suitable for springs and

components loaded by wear Gr 7 ja 8: For applications where improved corrosion resistance

is required. Gr 5: For applications where both high static and fatigue

strength are required.

Titanium alloys in generalDensity (in average) 4540 kg/m3Modulus of elasticity (in average) 108 000

N/mm2Melting temperature (in average)1670 oCProperties can be tuned by alloying

AluminumLeadNickelMolybdenumVanadium

The strength of titanium alloys exceeds the values of steels, but the weight is 45% lighter!

The weight of titanium alloys is 60% higher than the weight of aluminum alloys, but the strength is two time higher!

The maximum strength of the best titanium alloys is competitive with the best stainless and QT-steels!

The ultimate tensile strength can be increased up to 1700… n. 1800 MPa.

Titanium alloys

Titanium alloys in general

Good corrosion resistance

Good strength / weight-

ratio

Special application areas

Moderate manufacturability

Limited strength

properties in elevated

temperatures

Excellent properties

in cold environmen

ts

Disadvantage

Moderate

Advantage


Good strength / weight-

ratio

Disadvantage

Moderate

Advantage

Titanium alloys are used in applications, where high strength/weight-ratio is required together with good corrosion resistance.

Titanium turbine blades

By appropriate alloying the strength values can be increased but at the same time the values of modulus of elasticity will decrease!


Excellent properties

in cold environmen

ts

Disadvantage

Moderate

Advantage

Because brittle fractures are not very likely with titanium alloys, they are applied for cryogenic applications (temperatures below -80°C).

The yeld strength of titanium alloys increases while the temperature decreases.The impact strength of pure titanium and slightly alloyed titanium alloys increases while the temperature decreases.

Titanium has excellent corrosion resistance in cold environments.


Limited strength

properties in elevated

temperatures

Disadvantage

Moderate

Advantage?

+ 300°C -50% !

+ 500 °C -50% !

+ 300°C -20% !



Disadvantage

Moderate

Advantage

Titanium and titanium alloys are used in chemical process equipment and in wood processing industry if the corrosion resistance of stainless steels is not high enough.

Corrosive environment does not decrease the fatigue strength of titanium.

http://www2.catalognavigator.com/ticotitaniuminc/viewitems/flanges-weld-neck-and-threaded-flanges/raised-face-weld-neck-flanges?&plpver=10&forward=1&backtoname=&pane=

http://www2.catalognavigator.com/ticotitaniuminc/viewitems/bar-rod-wire/round-wires?&plpver=10&forward=1&backtoname=&pane=

Properly selected titanium alloys can withstand:

Seawater (corrosion rate not more than ~ 8 μm/v)

Wet chlorine (if humidity >0,005% H2O)

Nitric acid under its boiling temperature

Oxidising salines under their boiling temperatures CuCl2, FeCl3, CuSO4, K2Cr2O

Hypoclorites

Diluted Hydrochloric acid and Sulfuric acid

Titanium alloys do not withstand:

Hot alkaline salines

Dry Chloride

Nitric acid above its boiling temperature

Molten salines (e.g NaCl, LiCl, Fluorides, CaCl2 )

Hydrogen fluoride in water solutions (HF, fluoride acid)

Fluorine

Oxalic acid, Formic acid

Elevated temperature decreases the corrosion resistance even in normal air atmosphere



Disadvantage

Moderate

Advantage

Remember to check!

pH-range

Joint effects

Temperature

Humidity

Chemicals

Concentration

!



Disadvantage

Moderate

Advantage

Note: Insufficient surface roughness after machining or even a tiny crack on the surface of the titanium component decreases the fatigue strength remarkably!

Usually semi-productscan be used:- Sheet metal- Tubes- Bars- Profiles- Wires- Screws

In general, titanium’s weldability is good, because its thermal expansion is low and deformations due to heat input remain small. Usually TIG- or plasma processes are applied.

Weldability with other metals is poor, because of brittle compounds with other materials, which are formed during welding.

Welded constructions might suffer easily from porosity and decreased ductility due to titanium’s reactions withOxygen and Nitrogen during welding.

http://www2.catalognavigator.com/ticotitaniuminc/viewitems/plate-sheet/cp-titanium-plates?&plpver=10&forward=1&backtoname=&pane=




Disadvantage

Moderate

Advantage

Machinability is challenging due to:- addhesive reactions with the cutting tool- tendency to suffer from work-hardening- low modulus of elasticity- low thermal conductivity

Note: Insufficient surface roughness after machining or even a tiny crack on the surface of the titanium component decreases the fatigue strength remarkably!

Cold forming is easy for pure titanium and slightly allowed titanium alloys.

Titanium alloys tend to work-harden during the forming processes.





Disadvantage

Moderate

Advantage

One famous adaptive memory material is based on Titanium-Nickel-alloying

Titanium nitrides and carbides are used as coatings in cutting edges and other tools.

Utilization in cryogenic applications!

Selection of the best titanium

alloy for the product

REQUIREMENTSPROFILE


Light weighttogether with high strength

Good formability

Corrosion resistance

withhigh

strength and light weight

High strength

and light

weightUse in cold

environment

Grade 1

Grades 2…8

Grade 5(+ others)

Semi-products

Process industry

Airplanes etc. GRADES 1…8

Detailed alloys andtheir chemical composition



Magnesium alloys

Magnesium alloys in general

Limited corrosion resistance

Light weight

material


Standardized alloys

Limited strength

properties

Surprisinglygood

manufacturability

Disadvantage

Moderate

Advantage


Light weight

material

Disadvantage

Moderate

Advantage

Density 1740 kg/m3.Modulus of elasticity 45 000 N/mm2

Magnesium is the most light weight material for constructions.

Magnesium is used in applications where either the mass or inertia should be minimized (airplanes, camera bodies, vehicles etc.).


Surprisinglygood

manufacturability

Disadvantage

Moderate

Advantage

Magnesium alloys are available both for casting and forming.

If impurities are removed properly from the surfaces, magnesium alloys can be welded with TIG-, MIG- or ERW-processes .

Magnesium alloys can be machined easily with e.g. tools made of HS-steels by using high cutting speeds and large feeds.

There is always the risk of fire when magnesium is welded, machined or heat treated. Do not try to put out the fire with water!



Disadvantage

Moderate

Advantage


Disadvantage

Moderate

Advantage

Standardized alloys

Identification codes of magnesium alloys are based on ASTM standards.

Typical alloying components: Al (7-10 %)Zn (0.5-2.4 %) Mn ( 0.1 %)

E.g. AZ81A


Limited strength

properties

Disadvantage

Moderate

Advantage

With best magnesium alloys the yeld strength can exceed 300 MPa and tensile strength 400 MPa.


Limited corrosion resistance

Disadvantage

Moderate

Advantage

Sufficient corrosion resistance for the purposes of aircraft and process industries.

Corrosion resistance can be improved by adding the content of aluminium: Stress corrosion is almost totally avoided if the content of aluminium is Al%>1.5.

No risk of intergranular corrosion.

Fe, Ni, Co and Cu decrease the corrosion resistance at elevated temperatures.

High risk of galvanic corrosion with Fe, Ni, Cu ja Ti .

Chloride in water solution increases the corrosion speed.

Nickel-Based Superalloys

Nickel-Based

Superalloys

MONEL

NIMONIC

INVAR INCONELINCOLOY

HASTELLOYELINVAR

Nickel-Based

Superalloys

MONELNi 60-70%, rest Cu

Excellent corrosion resistance especially in seawater.

If Al and Ti are added, higher strength will be achieved.

Nickel-Based

Superalloys

HASTELLOY

Corrosion resistance is excellent even against hydrochloric acid and sulfuric acid.

These type of alloys are able to withstand fire!

Hastelloy B (65 % Ni, 30 % Mo, 5 % Fe)

Hastelloy C (64 % Ni, 16 % Cr, 16 % Mo)

Nickel-Based

Superalloys

INCONELINCOLOY

Corrosion resistance against various acids is excellent.

Are able to withstand fire!

Also creeping strength guaranteed up to 815°C.

- Inconel X (75 % Ni, 14 % Cr, 6 % Fe, 0.7 % Al, 2.5 % Ti, 1 % Nb, 0.05 % C)- Nimonic 80A (73 % Ni, 20 % Cr, 2,3 % Ti, 1,2 % Al

NIMONIC

Nickel-Based

Superalloys

INVAR

Fe-Ni-alloy (36% Ni) No remarkable heat expansion .

Nickel-Based

Superalloys

ELINVAR

Fe-Ni-Cr-alloy (34-37% Ni and 15% Cr). Modulus of elasticity is non-dependent of the temperature.

Gas turbine construction

Zinc alloysTypically used in mass production of pressure

casting Low melting points, easy to cast thin wall

thicknessesTypical aluminum content is about 4%By increasing the amount of aluminum (up to

8…27%), the strength can be improved

Scandium (Sc)Yttrium (Y) Lanthanum (La) Cerium (Ce)Praseodymium

(Pr)Neodymium(Nd)Promethium (Pm) Samarium (Sm) Europium (Eu)

Gadolinium (Gd) Terbium (Tb) Dysprosium (Dy) Holmium (Ho)Erbium (Er) Tulium (Tm) Ytterbium (Yb) Lutetium (Lu)

RARE-EARTH METALS

Catalytic converters

Metal-hybrid batteries

Permanet magnets

Metallurgy and material science

Polishing technology

Optics

Fluorescent materials

Oil refineries

Ce, La, Nd

La, Ce, Pr, Nd

Nd, Pr, Dy, Tb, Gd, Sm

Ce, La, Nd, Er, Gd, Yb

Eu, Y, Tb, La, Dy, Ce, Pr, Gd

Ce, Tb, Dy, Y

Ce, La, Pr

La, Ce, Pr, Nd

Vehicles, cars

Electric and hybrid cars

Electric and hybrid cars, wind energy

Cameras, lenses

Fluorescent lams, LCD-displays and -monitors

Steels, castirons, ceramics

Computer and mobile phone displays and monitors

Petrol (Gasoline)

Application area Materials Products

RARE-EARTH METALS

During the past few years the production of rare-earth metals has exceeded more than 130 000 tons. About 90% was produced in China.

The largest amounts of rare-earth metals production consist of Cerium ja Lanthanum (about 70 %)

Next come such materials as Neodymium, Yttrium, Praseodymium and Samarium.

From the view point of sustainability or green values in engineering it is sad that only 1% on rare-earth metals are recycled at the moment.

Due to the tiny amount on rare-earth metals in separate products it is not yet cost-effective to try to collect and recycle these materials.

One trend is to try to replace the rare-earth metals with some other materials or technologies to improve sustainability.

ECO-EFFICIENCY OF THE

MATERIAL

Minimize the amount of material(s)

If possible utilize waste material for energy production

Repair the product for its initial use and purpose

Utilize material for producing new products

Case example 1.Material group Key aspects of comparing corrosion resistance:

Titanium alloys Reasonable corrosion resistance in different types of environments together with reasonable strength. Expensive.

Stainless steels Tend to suffer from localized, crevice and stress corrosion and also corrosion fatigue. In general lower corrosion resistance compared with Titanium.

Reinforced plastic

Limited corrosion resistance together with limited highest operating temperature. Difficult to join.

Fluoropolymers Better resistance in acidic and alkaline environments compared to Titanium. Low strength. Difficult to join.

Copper alloys Reasonable price but only moderate corrosion resistance compared with Titanium

Nickel alloys Compared with Titanium maximum operating temperature is higher but structures become heaver and corrosion resistance is lower

Zircon Withstands better in reductive environments than Titanium. Expensive.

Tantalum Withstands better both in reductive and oxidation environments than Titanium. Expensive.

Case example 2.Requirements of a slide bearing Aluminiu

m bronze

Fluoro-polymer

PTFE

Property ratioAl :

PTFE

Maximum load bearing capacity 35 MPa 136 MPa 1 : 4

Maximum operating temperature 260°C 260°C 1 : 1

Wear resistance (adhesive wear in range 1…5)

4 2 2 : 1

Own mass(based on density)

7.6 2.6 3 : 1

Price(Relative)

90 200 1 : 2

lesson 4 2014. selection of metallic materials (other metallic materials than steels)

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