ME 207 – Material Science I
Chapter I
Engineering Materials
Dr. İbrahim H. Yılmaz
http://web.adanabtu.edu.tr/iyilmaz
Automotive Engineering
Adana Science and Technology University
Introduction
h Materials used in engineering applications cover a wide range
from simple
p dailyy uses ((e.g.
g p
pencils,, spoons)
p
) to most complex
p
and
extreme cases (e.g. space shuttles, biomedical purposes).
h Properties of such materials are of joint interest to the metallurgist,
the material scientist,
scientist and the engineer.
engineer
h Compared with material scientist and metallurgist,
metallurgist engineer does
not require deep understanding of the subject, but needs to know
which properties are important in different circumstances and
what limitations he could be faced with.
1
Engineering Materials
Metals and Alloys
Ferrous (iron based) Metals
Cast Iron (%C > 2):
Gray White,
Gray,
White Ductile,
Ductile Malleable,
Malleable High alloy
Steel (%C < 2):
Plain Carbon steels
steels, Alloy steels
Non-ferrous (iron free) Metals
Heavy Metals:
Copper, Chromium, Lead, etc.
Light Metals:
Titanium, Beryllium, etc.
Non-metals
Naturals: Wood,
Wood Granite
Granite, etc
etc.
Artificials
Polymers:
Rubber, Thermoplastics, Thermosets
Ceramics:
Glass, Cermets
Composites:
Metal matrix composites,
Ceramic matrix composites,
composites
Polymer matrix composites
Refractory (High Temp.) Metals:
Tungsten, Molybdenum, etc.
Precious Metals:
Gold, Silver, etc.
2
Metals vs. Artificials
h Metals are used to be the main engineering materials preferred
by
y mechanical engineers
g
for centuries.
h The main reasons for this were their existence in nature, easy
processing and also their relatively more load carrying capacity.
h However, artificial materials took place in many applications
due to their advantages such as better insulation, heat resistance
and weight saving.
h Therefore, many different materials were found or derived from
other materials for certain advantages in different applications.
applications
3
Ferrous Metals
h Ferrous metals are classified as cast irons (with > 2% C) and
steels ((with < 2% C).
)
h They are the most widely used materials in many engineering
applications.
h Steel, in particular, has many versions (alloys) with different
advantages for different applications.
h Steel can serve in applications varying from simple machine
construction to extreme load bearing (carrying) applications and
from simple springy (elastic) deflection applications to very high
temperature resistant or corrosion resistant applications.
4
Steel Making
h Steels are made by removing excess C and other impurities of pig
iron by
y !oxidation" p
process followed by
y !deoxidation" p
process,,
and addition of C and other alloying elements to the required level.
h Oxidation is carried out by blowing air or oxygen through molten
pig iron in either of following furnaces:
1. Bessemer-Thomas Furnace
2. Siemens-Martin (Open Heart) Furnace
3. Basic Oxygen
yg Furnace
4. Electric Furnace
h Steels can contain up to 2% Carbon (C), 1% Manganese (Mn),
0 5% Silicon (Si),
0.5%
(Si) 0.05%
0 05% Sulfur (S) and 0.05%
0 05% Phosphorus (P).
(P)
5
Steel Making Flowline (AISI Flow Sheet)
5 The pig iron is either
transformed into cast
iron or converted into
steels by a secondary
process.
4 The product of blast furnace is
called pig iron (i.e. impure iron)
containing
co
ta
g too much
uc C, Mn,, P,,
S and Si.
1 Iron is found in nature as iron ore which consist of iron oxides, carbonates and sulphides and gaunge.
2 Iron is obtained by reduction of iron oxides with carbon (i.e. coke) in the blast furnace.
3 Limestone is usually added into the blast furnace to remove gaunge (i.e. SiO2 as calcium silicate slags).
6
Steel Finishing Flowline (AISI Flow Sheet)
6 The steels in the form
of slabs, blooms and
billets are formed into
plates, coils and sheets
as well as tubes,
tubes bars
and rods, and various
structural shapes.
7
Plain Carbon Steels
h This is the first group of steels in which C is the significant alloying addition. They
contain up to 1.5% C and also 1.65% Mn (max), 0.6% Si (max), 0.6% Cu (max).
A. Low Carbon Steels
A1. Dead-soft mild steels: < 0
0.15%
5% C
C. Very
y soft,, easily
y fabricated by
y cold forming
g
and welding. Used in construction where strength is not very important.
A2. Mild steels: 0.15 - 0.30% C. Also known as !structural steels". Used for
structure, structure and machine applications, structural shapes like I-beams,
channels, angles etc.
B. Medium Carbon Steels: 0.30 - 0.60% C. Having combined properties of strength,
toughness and wear resistance. Used for crankshafts, axles, railway wheels, gears.
C. High Carbon Steels: 0.30 - 1.5% C. With low ductility. Used for high speed steels
(HSS) wire production,
(HSS),
production etc.
etc
D. Free Machining Carbon Steels: Specially developed for fast and economic
machining. Machinability of plain carbon steels is improved by addition of some
elements such as Pb (lead), S, P, Te (tellurium), Se (selenium), and Bi (bismuth).
8
Alloy Steels
h This is the second group of steels which contain modest amount of alloying
elements. They usually contain more than 1.65% Mn, 0.60% Si and 0.60% Cu.
h They can be heat treated to improve some mechanical properties. They have
through hardenable grades, carburizing grades, and nitriding grades.
h The alloying elements to be added into alloy steels may:
ƒ Form solid solution or intermetalic compounds in steel.
steel
ƒ Alter the temperature at which phase transformations occur.
iron
ƒ Alter the solubility of C in different phases of iron.
ƒ Alter the rate of transformation of austenite to its decomposition products
((i.e. the solution of cementite into austenite upon
p heating).
g)
ƒ Decrease the softening on tempering.
h Nearly all alloying elements dissolve in both ferrite and austenite, and increase
strength and hardenability of steels. Non-metalic inclusions (such as oxides
and
d sulphides)
l hid ) are deoxidizers
d
idi
and
d grain
i growth
h controllers.
ll
S l hid
Sulphides
and
d
nitrides increase hardness.
9
Effects of Alloying Elements
h Manganese (Mn): (1.65-2.1%) increases strength, hardenability, corrosion resistance.
h Titanium (Ti): increases yield point and weldability.
h Wolfram or Tungsten (W): increases hardness and tensile strength.
h Chromium ((Cr):
) increases hardness,, hardenability,
y, wear resistance,, corrosion resistance.
h Molybdenum (Mo): used with Mn & Cr to increase hardenability, tensile, creep strength.
h Vanadium (V): increases hardenability.
hardenability
h Nickel (Ni): increases strength, shock resistance, corrosion resistance, heat resistance
while lowers critical temp.
temp for heat treatment.
treatment
h Carbon (C): increases hardness & tensile strength, decreases forging & welding properties.
h Phosphorus (P): (0.03-0.05%) harmful (make steel brittle and prevent hot/cold forming).
h Sulfur (S): (0.025-0.05%) harmful (make steel brittle and prevent hot/cold forming).
h Aluminium (Al): promotes nitriding properties.
h Silicon (Si): (0.6-2.2%)
(0 6 2 2%) raises critical temp
temp. for heat treatment and increases resilience
resilience.
h Elemental Copper (Cu) & Lead (Pb): increase machinability.
10
Alaúõm Elementlerinin Çeliklerin Özelliklerine Etkileri
11
High Alloy Steels
h They are specially produced for specific purposes by using certain alloying elements.
A Tool Steels: clean (no inclusion) steels produced in electric furnaces.
A.
furnaces They usually
contain Cr, V, W, Mo or Co besides C, Mn, Si. They have wear resistance, high
g
and high
g hot hardness. These steels are used mainly
y in tools and dies.
toughness
B. Stainless Steels: contain 10.5% Cr (min). They have high strength, hardness,
corrosion resistance and abrasion resistance.
resistance Addition of higher amount
amo nt of Cr and Ni
improves corrosion resistance.
C. High Strength Steels: developed for specific high strength applications and used
for weight saving in constructions.
D. High Strength Low Alloy (HSLA) Steels: specially developed for improving
properties
p
and corrosion resistance while benefitting
g from weight
g saving.
g
mechanical p
E. Iron Based Super Alloys: cheaper than Co and Ni based super alloys, and used
for high temperature applications.
applications Super alloys are usually used at temperatures
from 540 to 1090 ºC. Iron based super alloys are used at lower end of this range.
12
Cast Iron
h Cast iron is a !four-element alloy" containing iron, carbon (2 - 4%),
g
Some g
grades may
y contain additional
silicon and manganese.
alloying elements.
h Cast iron contains large amount of carbon in the form of Fe3C
((cementite).
) This composition
p
is not stable and decomposes
p
under
certain conditions: Fe3C → 3Fe + C
h According to this breakdown of cementite, cast irons are classified:
ƒ Gray CI
ƒ Ductile CI
ƒ White
Whit CI
ƒ Malleable CI
ƒ High alloy CI
13
Types of Cast Iron
Gray CI:
h It g
gives g
gray
y fracture surface.
h Widely used in engineering applications.
h In manufacture,
manufacture cementite separetes into graphite and austenite or ferrite
by controlling the alloy composition and cooling rates.
h Most
M t gray CI are !hypoeutectoid
!h
t t id alloys"
ll
" containing
t i i 2.5
2 5 - 4% C.
C
h Individual grades depend upon the amount of graphite distribution pattern
and structure of iron around it.
Ductile (Nodular) CI:
h It is alloyed with magnesium which precipitates out carbon in the form of
small spheres.
spheres This improves some mechanical properties of gray CI.
CI
14
Types of Cast Iron
White CI:
h Produced by
y !chilling"
g p
preventing
gg
graphite
p
carbon from p
precipitating
p
g out.
h Either gray CI or ductile CI can be chilled to produce a white surface.
h Most of carbon is combined with iron as iron carbide (cementite) which is
a very hard material. Grades of white CI depend on the amount of
cementite in the surrounding structure.
structure
Malleable CI:
h White CI is converted to malleable condition by two-stage heat treatment.
h Malleable CI differs from others in the shape of contained graphite
existing as tempered carbon nodules as compared with graphite flakes in
gray CI and true carbon spheroids in ductile CI.
CI
h Two basic types are ferritic and pearlitic. The third type (martensitic) is
pearlitic or ferritic grade that has been heat treated and transformed to
martensitic structure.
15
Types of Cast Iron
High Alloy CI:
h Theyy are ductile,, g
gray
y or white CI containing
g over 3% alloyy content.
h They are usually produced in specialized foundries, and their properties
are significantly different from unalloyed CI.
CI
h Selection of the proper alloy for a casting is difficult since properties of
the finished part depend strongly upon size and shape of the part.
part
This is very important to bear in mind when deciding on casting process.
Gray CI
Ductile CI
White CI
Malleable CI
16
Designation of Steels
h There are various standardization bodies for steels:
1 American (AISI & ASTM)
1.
2. German (DIN)
3 Turkish
3.
T ki h (TS & MKE)
4. British (BS)
5. Euronorm
h Steels are usually designated by the criteria of:
ƒ Process of manufacture
ƒ Method of deoxidation
ƒ Chemical composition
ƒ Mechanical properties
17
Designation by Process of Manufacture
h The purification of pig iron into steel is accomplished by following
methods (the last two are the most widely used processes):
1. Basic Thomas or acid Bessemer converter
2. Open heart furnace
3. Electric furnace
4. Basic oxygen furnace
h The prefixes are used to designate steels produced by above methods:
American (AISI) standards
Turkish and DIN standards
A # Basic open hearth alloy
T # Thomas converter
B # Acid Bessemer carbon
O # Oxygen converter
C # Basic open hearth carbon
M # Open hearth furnace
D # Acid open hearth carbon
E # Electric arc furnace
E # Electric arc furnace alloy
I # Induction furnace
X # Composition varies from normal limits
18
Designation by Method of Deoxidation
h In steel making process, the primary reaction is the combination of carbon
and oxygen to form a gas. If the oxygen is not removed prior to or during
casting (by the addition of ferro-silicon or some other deoxidizer), then
gaseous products continue to evolve during solidification. This will cause
non-uniformity in microstructure of the steel. Proper control of the amount
of gas evolved during solidification determines the type of steel.
h Based on type of deoxidation, the steels are classified as below and
d i
designated
t d by
b the
th letter
l tt prefixes:
fi
Type
TS
DIN
Rimmed
K
U
Semi-killed
Semi
killed
Sy
H
Killed
S
R
S
Specially
i ll killed
kill d
#
RR
19
Designation by Method of Deoxidation
h Killed steels are completely deoxidized steels (i.e. no formation of carbon
monoxide). Aluminum and silicon may be added to combine chemically with
the oxygen,
oxygen removing most of it from liquid steel.
steel Ingots and castings of killed
steels have homogeneous structure and no gas porosity (blowholes).
Therefore, killed steels are recommended for hot forging, carburizing, piercing
and heat-treating applications where maximum uniformity is required.
hS
Semi-killed (capped)
(
) steels are incompletely deoxidized steels containing some
excess oxygen, which forms carbon monoxide during last stages of solidification.
These steels have relatively less uniform properties and composition due to
segregation (i.e. nonuniform variation in internal characteristics that results when
y g elements redistribute themselves during
g solidification).
)
various alloying
h For rimmed steels (with less than 0.25% C and 0.60% Mn), oxygen in the form
of carbon monoxide
mono ide evolves
e ol es quickly
q ickl throughout
thro gho t the solidification process.
process Ingots
of rimmed steels are characterized by practically carbon-free surface with
considerable quantity of blowholes. The outer skin of these steels is very
ductile, hence they are often specified for cold-forming applications.
20
Designation by Chemical Composition
h Following steel groups are designated by their chemical compositions:
1. Plain carbon steels
2. Alloy steels
3 Tool
3.
T l steels
t l
4. Stainless steels
5. HSLA steels
6. Super alloys
21
Designation of Plain Carbon Steels
h The general designation for plain carbon steels (which have only carbon as alloying
element) is CiXX where !XX/100" is carbon percentage and !i" refers to grade of
control of some alloying elements and some mechanical properties.
properties
Designation
C 10
Ck 10*
Cm 35
35*
Cf 35*
Cq 35*
CC 10
S 10 C
A 12
En 2C**
1225**
1010***
Ç1060***
Ç1060
St C 16.61***
C%
0 07 ! 0.13
0.07
0 13
0.07 ! 0.13
0 32 ! 0.39
0.32
0 39
0.32 ! 0.39
0.32 ! 0.39
0.05 ! 0.15
0.08 ! 0.13
0.08 ! 0.16
0.18 ! 0.23
0 08
0.08
0.08 ! 0.13
0 55 ! 0.64
0.55
0 64
0.10 ! 0.18
Designated by
DIN TS
DIN,
DIN, TS
DIN TS
DIN,
DIN, TS
DIN, TS
AFNOR (France)
JIS (Japan)
GOST (Russia)
BS (British)
SIS (Sweden)
(S d )
AISI, SAE (USA)
MKE (Turkey)
DIN (German)
* The letters k! and m! designate how
closely P and S content are controlled.
controlled
The letter f! specifies a steel suitable
for superficial hardening, and q!
specifies
ifi a steel
t l for
f cold
ld extrusion.
t i
** These designations have no inference
to carbon content.
content En! designation is
replaced by the new BS! designation
(e.g. a steel (0.16-0.24% C) designated
as En 3! is now BS
S 070M20!).)
*** St! is the old DIN designation that is
still
till usedd in
i Turkey
T k
f some steel
for
t l
products (e.g. 16.61! is cementation
steel with 0.16% C). For AISI and MKE,
the numeral 1! stands for carbon steel
and 10! designates plain carbon steel.
22
Designation of Alloy Steels
h In Turkey, mainly DIN and AISI designations are used. In DIN designation,
multiplication factors are used for the content of alloying elements:
Factor for Co, Cr, Mn, Ni, Si, W = x 4
Factor for Al, Cu, Mo, Ti, V
= x 10
Factor for C, N, P, S
= x 100
Steel
Average Percentage
14 NiCr 10
0.14% C, 2.5% Ni
15 CrNi 6
0 15% C
0.15%
C, 1
1.5%
5% Cr
13 Cr 2
0.13% C, 0.5% Cr
16 MnCrS 5
0.16% C, 1.25% Mn
20 MoCr 4
0.20% C, 0.4% Mo
39 CrMoV 13 9 0.39% C, 3.25% Cr, 0.9% Mo
9 S 20
0.09% C, 0.2% S
X120 Mn 12
1.20% C,, 12% Mn
X12 CrNi 18 9
0.12% C, 18% Cr, 9% Ni
h If Al (0.1%),
(0 1%) Cu (0.25%),
(0 25%) Mn (0.8%),
(0 8%) Si
(0.5%) and Ti (0.1%) are not exceeded,
such as steel is considered unalloyed.
h Low alloy steels contain not more than 5%
of alloy elements. When alloy contents
exceed 5% (i.e. high alloy steels), these
multiplication factors are not used
(except for carbon).
carbon) Instead,
Instead the letter
X! is put in front of carbon content
indicating that the number(s) at the end of
designation specify the alloy content.
23
Designation of Alloy Steels
h AISI (SAE) and MKE designations use 4-digit numbers: !XXXX"
h The
Th first
fi t two
t
di it indicate
digits
i di t the
th alloy
ll
classification,
l
ifi ti
and
d the
th last
l t two
t
(and in special cases, three) digits give the carbon content (x100).
See next page for complete table.
table
h For instance,
instance plain carbon steels is denoted by the basic numeral 10.
10
Thus, !Steel 1030" indicates a plain carbon steel containing 0.30% C.
h In some cases, capital letter prefixes or suffixes are added to designate
the type of process or hardenability. Some examples for the prefixes are:
C1020 (C: for basic open heart carbon)
B1112 ((B: for acid bessemer carbon))
A3140 (A: for basic open hearth alloy)
E52100 (E: for electric arc furnace alloy)
24
Designation of Alloy Steels
Carbon Steels
1xxx
Molybdenum Steels
4xxx
Plain Carbon
10xx
Carbon-Molybdenum
40xx
Free Cutting
11xx
Chromium-Molybdenum
41xx
Free Cutting "Leaded#
12Lxx *
Chromium-Nickel-Molybdenum
43xx
M
Manganese
St
Steels
l
13 xx
Ni k l M l bd
Nickel-Molybdenum
(1.75%
(1 75% Ni)
46
46xx
Nickel-Molybdenum (3.50% Ni)
48xx
Nickel Steels
2xxx
3 50% Ni
3.50%
23xx
Chromium Steels
5.00% Ni
25xx
Low Chromium
51xx
Medium
ed u C
Chromium
o u
52xx
5
Corrosion and Heat Resistant
51xx
Nickel-Chromium
c e C o u Steels
Stee s
3xxx
3
1.25% Ni, 0.60% Cr
31xx
1.75% Ni, 1.00% Cr
32xx
3.50% Ni, 1.50% Cr
33xx
Tungsten Steels
7xxx(x) **
Chromium-Nickel-Molybdenum
86xx, 87xx
Chromium-Vanadium Steels
1.00% Cr
Silicon-Manganese Steels
2.00% Si
5xxx
6xxx
61xx
9xxx
92xx
* The letter L (as in 12L13 steel) signifies a free cutting steel to which lead is added to improve machinability.
Likewise, the letter B
B (e.g. 81B45) signifies a minimum of 0.0005% boron added for hardenability.
The steels to meet certain hardenability requirement are designated by suffix H (e.g. 8637H, 94B15H, etc.)
** Used for certain tungsten alloys by SAE and MKE, such as 7245, 72100 and 71660.
25
Designation of Tool Steels
h These steels are divided into four broad groups as follows:
Group
p
German
Turkish
1
Carbon Tool Steels
Unalloyed Carbon Tool Steels
2
High-Speed
High
Speed Steels
Alloyed Tool Steels
3
Cold Work Tool Steels
Cold Work Tool Steels
4
Hot Work Tool Steels
Hot Work Tool Steels
Group 1: Carbon Tool Steels
h Designation of carbon tool steels is the same as that of carbon steels. The only
difference is that a quality symbol follows the usual designation.
h The quality symbol is "W" (W1, W2, W3) denoting an increase in the quality in
p
extra, best q
quality.
y The symbol
y
!WS# denotes a special
p
the order of special,
purpose tool steel (also used by Asil Çelik).
h Some examples
p
are: C125WS ((1.25% C with special
p
quality),
q
y) C110W2, C60W3.
h Designations by MKE and AISI are: Ç1090, Ç10100, Ç10115, etc.
26
Designation of Tool Steels
Group 2: High Speed Steels
h They are designated as: !S xx-yy-zz-uu# where !S# denotes high speed steel,
!xx-yy-zz-uu# is content of W-Mo-V- Co using no multiplication factors:
!S 10-4-3-10# means 10% W, 4% Mo, 3% V, 10% Co
!S 18-0-1#
18 0 1# means 18% W,
W 0% Mo,
M 1% V,
V 0% Co
C
Group 3 & 4: Cold & Hot Work Tool Steels
h They are designated according to the designation of alloy.
h DIN and ASøL Çelik uses the same designation as explained previously:
!40NiMo10 8# means 0.40% C, 2.5% Ni, 0.8% Mo
h MKE uses basic AISI designation for alloy steels, and tools steels are classified
into groups by the AISI. All these groups of tool steels and the corresponding
d i
designations
ti
are shown
h
i nextt page.
in
27
Designation of Tool Steels (AISI designation by MKE)
Cold Work
Type W (water hardening)
Commercial (W1xx), Extra (W2xx), Standard (W3xx), Special (W4, W5, W6, W7)
Type O (oil hardening)
O1 O2,
O1,
O2 O6,
O6 O7
Type A (air hardening)
A2, A3, A4, A5, A6, A7, A8, A9, A10
Type D (air hardening)
D1, D2, D3, D4, D5, D6, D7
Hot Work
Type H (chromium grades)
(tungsten grades)
H1 - H19
H20 - H39
(molybdenum grades) H40 - H59
High
Hi
h Speed
S
d
Type T (tungsten grades)
T1, T2, T3, T4, T5, T6, T7, T8, T9, T15
Type M (molybdenum grades) M1, M2, M3-1, M3-2, M4, M6, M7, M8, M10, M15, M30, M33, M34, M35, M36,
M41, M42, M43, M44, M46, M47, M50
Shock Resisting (Type S)
S1, S2, S3, S4, S5, S6, S7
Special Purpose
Type P (mould steels)
P1, P2, P3, P4, P5, P6, P20, P21
T
Type
L (l
(low alloy
ll steels)
t l )
L1 L2
L1,
L2, L3
L3, L4
L4, L5
L5, L6
L6, L7
Type F (carbon-tungsten alloy) F1, F2, F3
28
Designation of Stainless Steels
h These are widely used family of chromium alloys (min. 10.5% Cr), and they are
known for their corrosion resistance.
h DIN designation is the same as alloy steels: !X40 Cr 13#, !X12 CrNi 18 8#, !X20
Cr 13
13# are DIN designations of three types of stainless steel produced by MKE.
MKE
MKE's own designation of these steels is based on the basic SAE system:
!Ç51440#, !Ç3915#, !Ç51420# in the same order.
h AISI classifies wrought stainless steels into four groups based on metallurgical
structure,
t t
and
d designations
d i
ti
are similar
i il to
t alloy
ll steels:
t l austenitic
t iti (30201,
(30201 30316,
30316
30347, so on); ferritic (405, 430, 442, 446, 51405 and 51430); martensitic
((same as ferritic designation),
g
), and p
precipitation
p
hardening
g ((630 to 605).
)
h Cast stainless steels are considered as another group. DIN designation of cast
stainless steels is the same as that of the alloy steels only to be preceeded by
the letter G to indicate casting: G-X12Cr 14, G-X10CrNi 18 8, G-NiMo 30,
G X2NiCrMoCuN 25 20,
G-X2NiCrMoCuN
20 etc.
etc
29
Designation of HSLA Steels
h Steels of very high strength are usually proprietary, and hence they are
not specified
p
by
y the standard designations.
g
h However, there are some special designations or trade names. ASTM
classifies these steels into 6 groups based on their chemical composition
and mechanical properties. SAE specifies 12 grades with emphasis on
mechanical properties.
h Followings are the examples of typical SAE and ASTM designations:
Specification
Condition
SAE J410 C, ASTM A607
Semi-killed or killed
ASTM A606 (Type 2 and 4)
Improved corrosion resistance
ASTM 715 (sheet), ASTM A656 (plate) Inclusion controlled, improved formability, killed
30
Designation of Super Alloys
h Super alloys are designated by AISI 600 series with the specifications of
high temperature and high strength:
I. 601-604 : Martensitic low alloy
II. 610-613 : Martensitic second hardening
III. 614-619 : Martensitic chromium steels (616 is equivalent to X20CrMoWV 12 1)
IV. 630-635 : Semiaustenitic and martensitic precipitation hardening stainless steels
V 650-653 : Austenitic steels strengthened by cold/hot work
V.
VI. 660-665 : Austenitic super alloys (some of German equivalents are classified
under !Aviation Standard";; e.g.
g No. 1.4944 for 660 and 1.4974 for 661))
31
Designation by Mechanical Properties
h Steels for general structural purposes are designated by mechanical properties
by DIN, EURONORM and KARABÜK Demir Çelik (Turkey).
h !St xx-y#
xx y# is the DIN designation where !xx# is tensile strength and !y# is quality
grade number denoting maximum contents of P and S:
Symbol
Maximum Content
USt 37-1 (rimmed), RSt 37-1 (killed)
0.2% C, 0.07% P, 0.05% S
USt 37-2 ((rimmed),
), RSt 37-2 ((killed))
0.17-018% C, 0.05% P, 0.05% S
St 37-3 (RR specially killed)
0.17% C, 0.045% P, 0.045% S
USt 42-1, RSt 42-1
0.25% C, 0.08% P, 0.05% S
USt 42-2, RSt 42-2
0.23-0.25% C, 0.05% P, 0.05% S
St 42-3
0.23% C, 0.045% P, 0.045% S
RSt 46-2
0.2% C, 0.05% P, 0.05% S
St 46-3
0.2% C, 0.045% P, 0.045% S
h In Euronorm; Fe is substituted for symbol St,
the letters (A-D) are used instead of quality
numbers (1-3)
(1 3) and the yield strength is used
instead of tensile strength:
DIN
Euronorm
USt 34-1
Fe 34-A
RSt 34-2
Fe 34-B3FN
St 37-3
Fe 37-C3FN
32
Designation of Cast Irons
h It is not possible to specify cast iron by a standard chemical analysis. A single
analysis of cast iron can produce entirely different types of iron, depending upon
f
foundry
d practice,
ti
shape
h
and
d size
i off casting;
ti
allll off which
hi h influence
i fl
cooling
li rate.
t
Thus, iron is usually specified by mechanical properties.
Designation of Gray CI:
h It is designated by its tensile
strength. Some examples of
standards and corresponding
designations are shown (!xx#
is the tensile strength):
Standard
Designation
TS 1111 (T
(Turkish)
ki h)
2)
DDL # XX (kg/mm
(k /
DIN 1691 (German)
GL # XX (kg/mm2)
ASTM A48 (A
(American)
i
) Class
Cl
# XX (lb/in
(lb/i 2 x 1000)
BS 1452 (British)
Grade # XX (MPa)
Designation of White CI:
h Unlike gray CI, there are no specifications for white CI.
h Symbols of !DDB# and !GGW# are used to designate white iron in short form by
TS and DIN, respectively.
33
Designation of Cast Irons
Designation of Ductile (Nodular) CI:
h It is designated
g
by
y three-letter abbreviation followed by
y its tensile strength
g ((!xx# in
kg/mm2) such as !DDK-XX# in TS 1111 and !GGG-XX# in DIN 1693.
h ASTM designation (A339-55 and A396-58) of a typical alloy is: !xx-yy-zz# where
!xx# is the minimum tensile strength (in psi), !yy# is the minimum yield strength
(in psi), and !zz# is the percentage of elongation over 20 inches gauge.
Designation of Malleable CI:
h It is designated as !DDTS-xx# and !DDTB-xx# in TS 1111 and !GTS-xx# and
!GTW-xx# in DIN 1692 where !xx# is the minimum tensile strength.
h ASTM designation
d i
ti
i based
is
b
d on 5-digit
5 di it system:
t
!
!xxxyy#
# where
h
!
!xxx#
# multiplied
lti li d
by 100 is the yield strength (in psi) and !yy# is % elongation over 2 inches gauge
length
g ((e.g.
g !32510# means Sy
y = 32500 p
psi with 10% elongation).
g
)
34