Carbon and Alloy Steel PDF
Carbon and Alloy Steel PDF
Carbon and Alloy Steel PDF
Content:
–Introduction,
–Carbon steel
–Classification of alloy steel
–Effect of alloying elements.
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Steel - Introduction
Steels can be classified by a variety of different systems
depending on:
• The composition,
– such as carbon, low-alloy or stainless steel.
• The manufacturing methods,
– such as open hearth, basic oxygen process, or
electric furnace methods.
• The finishing method,
– such as hot rolling or cold rolling
• The product form,
– such as bar plate, sheet, strip, tubing or structural
shape
F
E L + Fe3C
P G
2.14 4.30
O
N 0.76 H
0.022
Cementite Fe3C
C
6.70
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Carbon steels
• Effects of carbon in the carbon steel,
increased hardness
increased strength
decreased weldability
decreased ductility
Machinability - about 0.2 to 0.25%
C provides the best machinability
AISI
60
10
:Nonresulfurized grades
10
:Resulfurized grades
11
:Resulfurized and rephosphorized grades
12
:Nonsulfurized grades; max Mn content > 1%
15
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Classification of carbon steel-Designation system:
• A letter prefix before the four-digit number
indicates the steel making technology:
SAE 1040
Carbon content(0.40 %)
• AISI B1020
– means non-modified carbon steel,
– produced in acid Bessemer and
– containing 0.20% of carbon
White
Cast Iron Steels
Grey
Low Alloy High Alloy
allowing formation of a
homogeneous solid solution
(austenite) containing up to
2.0 wt % of carbon or 2.8 wt
% of nitrogen
opposing tendencies
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High-Alloy Steels: Stainless Steels (SS)
(a) The austenitic SS:
• -Fe FCC microstructure at room temperature.
Typical alloy Fe-18Cr-8Ni-1Mn-0.1C
A4 increase
A3 Decrease
• Austenite-forming elements
•The elements Cu, Ni, Co and Mn
Disadvantage: work harden rapidly so more
difficult to shape and machine
• Advantages of ALL fcc metals and alloys
toughness;
ductility;
creep resistance
Lower A4
Increase the A3
Ferrite-forming elements
AISI-SAE Classification
Letter & Number Identification
Classification
Letters pertain to significant characteristic
W,O,A,D,S,T,M,H,P,L,F
– E.g. A is Air-Hardening medium alloy
Numbers pertain to material type
1 thru 7 (E.g. 2 is Cold-work )
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High-Alloy Steels: Tools steels
• Provide the necessary hardness with simpler
heat-treatment and retain this hardness at
high temperature.
• The primary alloying elements are:
– Mo, W and Cr
• Examples:
– First digit: 1 indicates carbon steel (2-9 are used for alloy
steels);
– Second digit indicates concentration of the major element
in percents (1 means 1%).
– Last two ( three) digits indicate carbon concentration in
0.01% ( 0,001%).