Transcript Other metallic materials than steels

Lesson 4
2014
Selection of metallic materials
(other metallic materials than steels)
Metallic materials
- Caebon steels
- QT-steels
- Carburizing
steels
- Stainless steels
- etc.
Aluminum
alloys
Titanium
alloys
Magnesium
alloys
Other metallic
materials than
steels
STEELS
Nickel
alloys
REMEMBER
TO WIDEN
THE SELECTION
AREA…
Zinc alloys
Copper
alloys
Aluminum alloys
Disadvantage
Moderate
Advantage
Small
density
Relatively
good
corrosion
resistance
Easy
formability
Aluminum
alloys in
general
Limited
strength
and stiffness
properties
Good heat
conductivity
Good
electrical
conductivity
Disadvantage
Moderate
Aluminum’s density is about
1/3 of steel’s density
BUT
Advantage
Small
density
Aluminum’s modulus of elasticity
is also about 1/3 of steel’s modulus
of elasticity
THEREFORE
It is not so self-evident how much
lighter the aluminum construction
might be…
IN GENERAL
The equal strength and stiffness
properties are achieved with an
aluminum structure which is only
about 50 % lighter that the
corresponding steel structure.
Aluminum
alloys in
general
Steel
Aluminum 
Disadvantage
Moderate
Advantage
Depends on the
affecting chemical
environment
- acidic alkaline
- pH-value
- mediums
- Temperature
- sea water
- etc.
Depends on the
alloying of the
selected aluminum:
- Copper
- Magnesium
Relatively
good
corrosion
resistance
Aluminum
alloys in
general
 Corrosion resistance of aluminum alloys
 In 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
Corrosion speed
 The oxide layer is able to protect aluminum’s
surface only between the pH-range of 4…8.5
Acidic
Neutral
Alkaline
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
Aluminum
alloys in
general
Very corrosive:
- Lye
- Sodium sulfide
- Hydrochloric acid
- Hydrofluoric acid
- Sulfuric acid
- Chlorine
- Phosphoric acid
Aluminum’s melting point is
only 658°C and low creeping
strength might become a
problem not higher than at
> 100°C.
Disadvantage
Moderate
Advantage
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.
Aluminum
alloys in
general
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.
Limited
strength
and stiffness
properties
Disadvantage
Moderate
Aluminum’s thermal
conductivity is three
times better compared
with steels and cast
irons. This property is
utilized e.g. in
electromechanical
industry.
Advantage
Aluminum
alloys in
general
Good heat
conductivity
Good
electrical
conductivity
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.
Disadvantage
Moderate
Advantage
Different types of
standardized aluminum
profiles are available.
Easy
formability
Profiles and plates can be
coated for several
purposes.
Especially good formability
can be achieved with
magnesium and silicon
alloyed aluminums.
Aluminum
alloys in
general
Due to aluminum’s easy
formability customized
profiles can easily be
manufactured by
extrusion.
Improved ductility and
machinability
Risk of corrosion
Suitable for heat treatments
EN-AW-2007 Excellent for
turning
2000-series
Aluminum
with copper
alloying
7000-series
Aluminum
with zinc
alloying
High strength
but poor weldability
Suitable for heat treatments
EN-AW-7050 Airplanes
EN-AW-7075 Airplanes
3000-series
Aluminum
with
manganese
alloying
1000-series
Pure
aluminum
Electrical
conductivity
(other alloys 8000-series)
6000-series
Aluminum
with
magnesium
and silicon
alloying
Moderate weldability, corrosion resistance
and good formability
No heat treatments available
EN-AW-3103 Car bodies
4000-series
Aluminum
with silicon
alloying
Suitable for casting
and powder
metallurgy
5000-series
Aluminum
with
magnesium
alloying High corrosion resistance
in seawater
No heat treatments available
EN-AW-5754
Good suitability for anodizing
Suitable for heat treatments
EN-AW-6082 The mostly used grade in
mechanical engineering
EM-AW-6063 Aluminum profiles, tubes
REQUIREMENTS
PROFILE
PAY SPECIAL
ATTENTION
TO CLARIFY
THE FOLLOWING
REQUIREMENTS:
1. Corrosive
environment
2. Temperature and
acidic/alcaline
ranges
3. Possible dynamic
loading
4. Intended
manufacturing
methods in
production
COMPARISON
OF MATERIAL
PROPERTIES
Selection of
the best
aluminum
alloy for the
product
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.
COMPARE
CAREFULLY
AVAILABLE
DIFFERENT
OPTIONS:
1) 1000…8000 series
(optimum alloying)
2) Heat treatments
(if possible)
3) Anodizing
4) Standardized
profiles and other
bulk materials
Remember, that it is important to recycle
aluminum!
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
Pure copper
Brasses
Oxygenfree
copper
Bronzes
Pure copper
and copper
alloys
Deoxidized
copper
Nickel
Silver
Tough
pitch
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 alloys
 Copper 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
Disadvantage
Moderate
Easy
formability,
Moderate
strength
properties
machinability
and
castability
Advantage
Some
special
properties
available
Pure copper
and copper
alloys in
general
Good
electrical
and thermal
conductivity
Poor
weldability
Relatively
good
corrosion
resistance
Disadvantage
Moderate
Advantage
Pure copper
Good
electrical
and thermal
conductivity
High electrical conductivity:
Cu-OF (oxygen-free copper)
Extremely high electrical
conductivity:
Cu-OFE (oxygen-free copper,
electronic grade)
Disadvantage
Moderate
Advantage
Easy
formability,
machinability
and
castability
By using suitable alloying
copper alloys have
good castability properties
Copper alloys have excellent
formability properties both
for cold and hot forming.
Pure copper
and copper
alloys in
general
Unlike usually known che
machinability properties of
copper alloys, especially many
brasses, are excellent.
Maybe this is because pure copper is
difficult for machining.
Disadvantage
Moderate
Copper alloys are nonmagnetic metallic materials.
Some
special
properties
available
Advantage
Copper alloys have good
resistance against the
growth of microbes.
Pure copper
and copper
alloys in
general
Copper-Beryllium alloys have
excellent wear resistance.
However, they have poor
machinability and weldability
properties.
Disadvantage
Moderate
 Good corrosion resistance in
Advantage
freshwater
seawater,
steam
soil
climatic conditions
 corrosion rate 0-2,2 µm/year





In sulphuric conditions
corrosion resistance is poor
Typical corrosion types are:
Pure copper
and copper
alloys in
general
Because copper is a relatively noble
metal, it can cause the reaction of
galvanic corrosion with the adjacent
materials
Relatively
good
corrosion
resistance
Erosion
- Flow rates in tubes and
pipelines should be limited
Selective corrosion
- Dezincification of brasses
Stress corrosion
- Especially brasses suffer
from stress corrosion
- Nitrides and ammonia
increase the risk
Disadvantage
Moderate
Ultimate tensile strength
and 0.2-limit decrease
when temperature
increases.
Advantage
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
Moderate
strength
properties
Pure copper
and copper
alloys in
general
Strength is highly
depending
on the alloying, temper
designation and
manufacturing process .
Modulus of elasticity, 0.2limit, ultimate tensile
strength and elongation to
fracture increase when the
temperature
decreases.
Ductility increases when the
temperature decreases.
Disadvantage
Moderate
 Poor weldability




Advantage
porosity of seams
decreased strength
Decreased ductility
Strict requirements of cleanness
Pure copper
and copper
alloys in
general
Poor
weldability
Standardization
 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.




Examples:
Cu-OF-04
CuZn39Pb2
GZ-CuPb10Sn
 Some application areas of copper:






Constructions where climatic loading is affecting
Water piping lines
Seawater applications
Heat exchangers
Steam power plant applications
Electrical industry
Nuclear fuel waste management
Comparison of steels and
copper alloys
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.
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 conditions
 Lower 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
GROUND
PLANE
POWER
FEEDING
PINS
BODY MADE OF
FOUR-CORNERED
BARS
POWER
FEEDING
STRIPS
REAR
PLATE
HOUSING OF
ELECTRONICS
N-TYPE
CONNECTORS
JOINING
COMPONENTS OF
THE SMART ANTENNA
Oxygen free Cu-OF
Best electrical conductivity
Maximum performance
Deoxicidized Cu-DHP
Moderate electrical conductivity
Acceptable weldability
Performance about 70% of the
maximum
Copper-Tin alloy CuSn6
Moderate electrical conductivity
Good corrosion resistance
Moderate weldability
Property to function as a spring
is possible
Performance only about 10% of
the maximum
COMPARISON
OF MATERIAL
PROPERTIES
REQUIREMENTS
PROFILE
Wires
Electrical
conductivity
Piping
Thermal
Conductivity
Corrosion
Resistance
Easy
Formability
Easy
Machinability
Easy
Castability
Corrosion
resistance
PURE
COPPERS
Oxygen
free
coppers
Selection of
the best copper
alloy for the
product



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.
PURE
COPPERS
deoxidized
coppers
Components
Machine parts
BRASSES
BRONZES
OTHER
COPPER
ALLOYS
Titanium alloys
ASTM
Grade 1
ASTM
Grades
2 and 3
Other
grades
Different
grades of
titanium
alloys
ASTM
Grades
7 and 8
ASTM
Grade 4
ASTM
Grade 5
Most important alloys:
Some typical application areas:
 Gr 1:
 Gr 2 ja 3:
 Gr 4:
 Gr 7 ja 8:
 Gr 5:
Good formability e.g. for stretch forming or deep drawing.
Grades for many applications in chemical process
industrial and mechanical engineering
High hardness, which suitable for springs and components
loaded by wear
For applications where improved corrosion resistance is
required.
For applications where both high static and fatigue strength
are required.
Titanium alloys in general
 Density (in average) 4540 kg/m3
 Modulus of elasticity (in average) 108 000 N/mm2
 Melting temperature (in average)1670 oC
 Properties can be tuned by alloying
 Aluminum
 Lead
 Nickel
 Molybdenum
 Vanadium
 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.
Disadvantage
Titanium alloys
Moderate
Advantage
Good
corrosion
resistance
Excellent
properties
in cold
environments
Limited
strength
properties in
elevated
temperatures
Titanium
alloys in
general
Special
application
areas
Moderate
manufacturability
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
Titanium
alloys in
general
Good
strength /
weight-ratio
By appropriate alloying the
strength values can be
increased but at the same time
the values of modulus of
elasticity will decrease!
Disadvantage
Moderate
Advantage
Excellent
properties
in cold
environments
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
alloys in
general
Because brittle
fractures are not very
likely with titanium
alloys, they are
applied for cryogenic
applications
(temperatures below
-80°C).
Titanium has excellent
corrosion resistance in cold
environments.
Disadvantage
?
Moderate
Advantage
Limited
strength
properties in
elevated
temperatures
Titanium
alloys in
general
+ 500 °C 
-50% !
+ 300°C 
-20% !
+ 300°C 
-50% !
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.
Good
corrosion
resistance
Titanium
alloys in
general
Corrosive
environment does
not decrease the
fatigue strength of
titanium.
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
Chemicals
Humidity
Concentration
Good
corrosion
resistance
Remember
to check!
Joint
effects
Temperature
pHrange
Titanium
alloys in
general
!
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 with
Oxygen and Nitrogen
during welding.
Disadvantage
Moderate
Advantage
Titanium
alloys in
general
Usually
semi-products
can be used:
- Sheet metal
- Tubes
- Bars
- Profiles
Moderate
manufacturability - Wires
- Screws
Note: Insufficient surface roughness after
machining or even a tiny crack on the surface of the
titanium component decreases the fatigue strength
remarkably!
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
Cold forming is easy
for pure titanium and
slightly allowed
titanium alloys.
Titanium alloys tend
to work-harden
during the forming
processes.
Titanium
alloys in
general
Moderate
manufacturability
Note: Insufficient surface roughness after
machining or even a tiny crack on the surface of the
titanium component decreases the fatigue strength
remarkably!
Disadvantage
 One famous adaptive
memory material is
based on TitaniumNickel-alloying
 Titanium nitrides and
carbides are used as
coatings in cutting
edges and other tools.
 Utilization in
cryogenic
applications!
Special
application
areas
Moderate
Advantage
Titanium
alloys in
general
COMPARISON
OF MATERIAL
PROPERTIES
REQUIREMENTS
PROFILE
Light weight
together
with high
strength
Good
formability
Semi-products
Corrosion
resistance
with
high
strength and
light weight
Process industry
High
strength and
light weight
Use in cold
environment
Grade 1
Selection of
the best
titanium alloy
for the product
 GRADES 1…8
Detailed alloys and
their chemical composition
Grades 2…8
Airplanes etc.
Grade 5
(+ others)
Disadvantage
Magnesium alloys
Moderate
Advantage
Limited
corrosion
resistance
Surprisingly
good
Limited
strength
properties
manufacturability
Magnesium
alloys in
general
Special
application
areas
Standardized
alloys
Light weight
material
Disadvantage
Moderate
Advantage
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.).
Magnesium
alloys in
general
Density 1740 kg/m3.
Modulus of elasticity 45 000 N/mm2
Light weight
material
Disadvantage
Moderate
Advantage
Magnesium alloys are
available both for
casting and forming.
Surprisingly
good
manufacturability
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!
Magnesium
alloys in
general
If impurities are removed
properly from the surfaces,
magnesium alloys can be welded
with TIG-, MIG- or ERWprocesses .
Disadvantage
Moderate
Advantage
Magnesium
alloys in
general
Special
application
areas
Disadvantage
Moderate
Advantage
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
Magnesium
alloys in
general
Standardized
alloys
Disadvantage
Moderate
Advantage
With best magnesium
alloys the yeld strength
can exceed 300 MPa and
tensile strength 400 MPa.
Limited
strength
properties
Magnesium
alloys in
general
Disadvantage
 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.
Moderate
Advantage
Limited
corrosion
resistance
Magnesium
alloys in
general
 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
MONEL
ELINVAR
HASTELLOY
Nickel-Based
Superalloys
INCONEL
INCOLOY
INVAR
NIMONIC
Ni 60-70%, rest Cu
MONEL
Excellent corrosion
resistance especially
in seawater.
If Al and Ti are added,
higher strength will be
achieved.
Nickel-Based
Superalloys
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)
HASTELLOY
Nickel-Based
Superalloys
- 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
Corrosion resistance
against various acids is
excellent.
Are able to withstand
fire!
Nickel-Based
Superalloys
INCONEL
INCOLOY
Also creeping strength
guaranteed up to 815°C.
NIMONIC
Fe-Ni-alloy (36% Ni)
No remarkable heat expansion .
Nickel-Based
Superalloys
INVAR
ELINVAR
Nickel-Based
Superalloys
Fe-Ni-Cr-alloy (34-37% Ni and 15%
Cr).
Modulus of elasticity is nondependent of the temperature.
Gas turbine construction
Zinc alloys
 Typically used in mass production of pressure casting
 Low melting points, easy to cast thin wall thicknesses
 Typical aluminum content is about 4%
 By increasing the amount of aluminum (up to 8…27%),
the strength can be improved
RARE-EARTH METALS
 Scandium (Sc)
 Gadolinium (Gd)
 Yttrium (Y)
 Terbium (Tb)
 Lanthanum (La)
 Dysprosium (Dy)
 Cerium (Ce)
 Holmium (Ho)
 Praseodymium (Pr)
 Erbium (Er)
 Neodymium(Nd)
 Tulium (Tm)
 Promethium (Pm)
 Ytterbium (Yb)
 Samarium (Sm)
 Lutetium (Lu)
 Europium (Eu)
RARE-EARTH METALS
Application area
Materials
Products
Catalytic converters
Ce, La, Nd
Vehicles, cars
Metal-hybrid
batteries
La, Ce, Pr, Nd
Electric and hybrid cars
Permanet magnets
Nd, Pr, Dy, Tb, Gd, Sm
Electric and hybrid cars, wind
energy
Optics
Ce, La, Nd, Er, Gd, Yb
Cameras, lenses
Fluorescent materials
Eu, Y, Tb, La, Dy, Ce,
Pr, Gd
Fluorescent lams, LCDdisplays and -monitors
Metallurgy and
material science
Ce, Tb, Dy, Y
Steels, castirons, ceramics
Polishing technology
Ce, La, Pr
Computer and mobile phone
displays and monitors
Oil refineries
La, Ce, Pr, Nd
Petrol (Gasoline)
 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.
Utilize material
for producing
new products
Minimize the
amount of
material(s)
ECO-EFFICIENCY
OF THE
MATERIAL
Repair the
product for its
initial use and
purpose
If possible utilize
waste material for
energy production
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
Aluminium
bronze
Fluoropolymer
PTFE
Property
ratio
Al : PTFE
Maximum load bearing capacity
35 MPa
136 MPa
1 : 4
Maximum operating temperature
260°C
260°C
1 : 1
4
2
2 : 1
Own mass
(based on density)
7.6
2.6
3 : 1
Price
(Relative)
90
200
1 : 2
Wear resistance
(adhesive wear in range 1…5)