Part II, Engineering materials
Application of Materials
Structural strength
Strenth of Materials
Stiffness Reliability Lifetime
Strength of materialsProperties determined at tensile/compression tests
Jäävp ike nem ine
K o gup ike nem in e
L , m m
F m ax
F eH
F eL
N
m m 2
R m
R p0,2
0
AA t
Permanent elongation
Total elongation
Criteria for materials selection plastic materials – yield strength (yield limit) –
Re, Rp (Rec, Rp
c)
brittle materials – strength limit – Rm (Rmc), Rm/
Classification of materials (Re, Rp0,2) low strength < 250 N/mm2
medium strength 250...750 N/mm2
high strength 750...1500 N/mm2
super high strength > 1500 N/mm2
Stress concentration
t
R m
ax
m
m
F F
FF
R
tm 2max
Stiffness
E = tg
K =E
E =
G = tgG =
K = tgK =
G =3/8E
E
N o rm a a l- N ih k e - M a h t-
Stiffness D = Ex K(geometric characteristic of cross-section)
At tension K = S (cross-section area)At bending K = I (moment of inertia) I = bh3/3
Modulus of elasticity
Normal Shear Volume
Modulus of elasticityMaterial E, N/mm2 x 109
DiamondWCSiCAl2O3TiCMo & Mo-alloysCo & Co-alloysNi & Ni-alloysSteelsCast ironsCu & Cu-alloysTi & Ti-alloysZn & Zn-alloysAl & Al-alloysSn & Sn-alloysGraphitePb & Pb-alloysPlasticsRubbersPVC
1000450-650500390380320-360200-250130-230190-210170-190120-15080-13045-9070-8040-5030151-50,01-0,10,003-0,01
T KU, KV – cold brittleness
TDBT – ductile-to-brittle transition
Reliability (1)Toughness – notch impact energy KU or KV, J – fracture toughness KC, N/mm2 m1/2
T T TT K H L T K H L T K H L
1 00
5 0
0
T 5 0
Kiu
lise
pinn
a %
K UK U
TDBTT’DBTTDBT
Duc
tile
fra
ctur
e %
5 5
5 5
1 0
1 0
2
1010
R 0 .25
R 1 .0
5
4 5
Reliability (2)Influence of C, ordinary and alloying elements to KU
normal
cold worked
cold worked
el steel
TDBT
TDBT
TDBT CTDBT C
TDBT
Reliability (3)
% of alloying elements
Duc
tile-
to-b
rittl
e tr
ansi
tion
T50
, C
Reliability (4)
Kõrgtugev
Madaltugev
Temperatuur
Pur
ustu
stöö
A , J
15,4
14,0
12,6
11,2
9,8
8,.4
7,0
5,6
4,2
2,82 3 4 5 6 7 8 Tera nr.
U KU, J
low strength
high strength
T
KU
, KV
Grain no.
Dependence of KU/KV on temperature
Dependence of M toughness of A-grain size
Fine and coarse grain steels
T, C T, C
1 20 0 1 20 0
11 0 0 11 0 0
1 00 0 1 00 0
9 00 9 00
8 00 8 00
7 00 7 00
6 00 6 000 0 ,5 1 ,0 1 ,5
A
A 3
A cm
A + F
A + T
A 1
F + TF
C %
12
A C 1
d A
d P d
a b
1 – killed steel2 – rimmed steel
Influence of microalloying elements
Vanaad ium
Titaan
N io ob ium
1 40
1 20
1 00
8 0
6 0
4 0
0
2 0
0 0,02 0,060,04 0,10 0,120,08
L egee riva te e lem en tid e %
Fer
riid
i ter
a,
m2
Alloying elements, %
Gra
in s
ize
of f
erri
te,
m2
V
Ti
Nb
Plane strain fracture toughness K1c
At tension K1c
a
F
F
b
Coefficient of stress intensity
aK maxmax [MPam1/2]
Relationship between K1c and yield strength
Material K1C, MPa
m1/2
WCTiCSiCAl2O3
SiO2
Steels-low carbon-maraging
(E)6 (680)4 (440)3 (420)3 (320)
0,7 (100)54
110-175
Superplastic steels
Maraging steels
Low-alloyed highly tempered steels
Precipitation hardened stainless steels
Fra
ctur
e to
ughn
ess
K1c
, MP
a
m1/
2
Yield strength, MPa
Life time (1)Fatigue
F
P in geepüür
N 1 10 7N 2 N 3 N
R
a b
Steels N = 107Nonferrous alloys N = 108
Impactors:- surface roughness- stress state- stress concentrations
R (R = min/max)-1 – symmetric loading
Life time (2)
Material Rp0,2, N/mm2
-1,
N/mm2
Plain carbon steel-strain hardened-annealedAlloyed steelAl-alloys-wrought alloys-cast alloysTi-alloysCu-alloys
275475
1700275110900450
24034070010080
500150
Life time (3)
Creep = f(, T, t) low temperature T/Tm < 0.5 high temperature T/Tm > 0.5
Impactors structure alloying (super creep alloys) – TMT
7501000/0.1
Corrosion
Modes of corrosion
Chemical
Electrochemical
Biochemical
in dry gases
in organic liquids
in water containing environments
in melt electrolytes
Types of corrosionTypes of corrosion:
a – uniform
b – nonuniform
c – selective
d – spotted
e – pitting
f – dotted
g – under surface
h – intercrystal
i - stress
Chemical corrosion of metals (1)
2 Mg + O2 = 2 MgO
2 Fe + 3 O2 = Fe2O3
For protection Voxide > Vmetal
Kui Voxide/Vmetal > 1 – Cd, Al, Ti, Zr, Zn, Ni, Cr, Fe
At high Voks / Vmet (1,2…2,0) cracking
High temperature corrosion
T 1000 C – oxide layer electroconductive
Chemical corrosion of metals (2)
Corrosion influencing parameters structure surface treatment materials parameters internal stresses T
gas composition velocity environmental parameters heating parameters
Chemical corrosion of metals (3)
Protection alloying ( ) coatings protective atmosphere (at heat treatment) (H2 + N2
+ H2O; CO + CO2 + N2; etc.)
metalbaseion
.el.allion
metalbaseoxide
el.alloxide rr,FF
Electrochemical corrosion of metals (1)Moisture + H2S, Co2,
So2, NaCl electrolyte
metals galvanic pair
Normal potential E, V
Galvanic series
Normal condition Sea water
-2,37 Mg Mg
-1,66 Al Zn
-1,63 Ti Cd
-1,18 Mn Al
soft steel
-0,76 Zn Pb
-0,74 Cr Sn
Ni
-0,44 Fe brass
-0,40 Cd Cu
-0,25 Ni monel (Ni alloy
-0,14 Sn Cr-steel (13% Cr)
0,13 Pb Ti
+0,34 Cu Cr
+0,80 Ag Ag
+1,20 Pt Au
+1,50 Au Pt
Electrochemical corrosion of metals (2)
Microgalvanic pairs at steels
Atmosphere
Moisture film
Metal
Electrochemical corrosion of metals (3)
Protection (1) Selection of materialsTable: Allowed contacts of metals
GroupI II III IV V
Mg Al Fe Ni TiZn plain
carbon steel
Cr Cu-Ni alloy
Cd Pb Stainless steel
Cu-Zn alloy
Sn Cr-steel CuAg, Au
Protection (2)
Protective coatings- metallic (less active metals (Cu, Ni, Sn, Ag) – up
to coating must be undamage; active (Zn, Co) – protection up to end)
- paints, lubricants other
- cathodic protection- protector protection- anodic protection- corrosion inhibitors (high molecular matters)
Wear
Modes of wear
Mechanical Corrosive-mechanicalAdhesive
-abrasion -oxidizing wear-erosion -fretting corrosive wear-cavitation-fatigue wear
Method for wear protection
hardening, thermo-chemical treatment overwelding surface alloying coating (chemical, thermo-chemical, thermally
sprayed, PVD, CVD, mechanical) selection of pairs (by adhesion)
Wear testing methodsDescription
Sliding friction with or without a lubrication
Abrasive wear
Rolling friction with or without a lubrication
Material groups
Metals
Ceramics
Glass
Composites
Polymers
Cermets
Glass-ceramics
MCM
MCM Metal composite materialsCCM Ceramic composite materialPCM Polymeric composite materialGCCM Glass-ceramic composite materialFRG Fiber-reinforced glass
CCM
PCM
GCCM
FRG
Material group kg/m3
Rm
N/mm2
Rm/
up to
Metals an
d allo
ys
Cast ironsPlain carbon steelsAlloy steelsAl-alloysCu-alloysTi-alloysMg-alloys
7800780078002700890045001750
150…800320…1000460…1650150…500230…700300…1450150…335
1013211883220
Plastics
PVCPEPCFiberglass plastic EP . PC
1350950105012501250
10…2520…4035…8030…9080…170
8
14
Specific strength of materials (1)
Specific strength of materials (2)
Material group kg/m3
Rm
N/mm2
Rm/
up toCera-mics
Al2O3
TiO2
3Al2O3 2SiO2
SiC (-modif.)Si3N4
39804240316032203170
300…40070…170110…190450…800500…1000
10462522
Compo-sites
Al-B (30%)Al-B (50%)Fiberglass plastic EP
ECCarbon-Carbon composite 3-directions
2700
1250
8011030…9080…170
4
14
35 (2000C)5 (3000C)
Wood PineOak
550 II690 II
8997 17
Basic physical and mechanical properties of construction materials (1)
Property Metals Ceramics Polymers
Density, kg/m3 x 10-3
2-6 (average.
8)
2-17 (average.
5)1-2
TS, C
Low. High.
Sn232, W3400
High 4000
Low
Hardness Average High LowWorkability Good Poor GoodTensile strength Rm,
MPa 2500 400 120
Compressive strength Rm
c,
MPa 2500 5000 350
Basic physical and mechanical properties of construction materials (2)
Property Metals Ceramics PolymersModulus of elasticity, E GPa
40 400 150 450 0,001 3,5
Creep resistance at high temperatures
Poor Outstanding -
Thermal expansion
Average High
Low Average
Very high
Thermal conductivity
Average
Average (mostly
lowers then t )
Very high
Electrical properties
Conductors Isolators Isolators
Chemical inertness
Low average
OutstandingGood in general
Thank you for attention