|
Classification of steel
according to AISI standard
| AISI |
Types of
Steel |
Alloy
Elements % |
| 10 |
Plain
Carbon |
0.4 Mn |
| 11 |
Free
machining |
0.7 Mn, 0.12 S |
| 13 |
High
Manganese |
1.6 - 1.90
Mn |
| 2 |
Nickel
Steels |
3.5 - 5.0
Ni |
| 3 |
Nickel
Chromium |
1.0 - 3.5
Ni, 0.5 -1.75 Cr |
| 40 |
Molybdenum |
0.15 - 0.3
Mo |
| 41 |
Chrome-Molybdenum |
0.80 -1.1
Cr, 0.15 - 0.25 Mo |
| 43 |
Nickel -
Chrome - Molybdenum |
1.65 - 2.0
Ni, 0.4 - 0.9 Cr, 0.2 - 0.3 Mo |
| 46 |
Nickel -
Molybdenum |
1.65 Ni,
1.65 Mo |
| 5 |
Chromium |
0.4 Cr |
| 61 |
Chromium -
Vanadium |
0.5 - 1.1
Cr, 0.1 - 0.15 Va |
| 81 |
Nickel -
Chrome - Molybdenum |
0.2 - 0.4
Ni, 0.3 - 0.55 Cr, 0.08 - 0.15 Mo |
| 86 |
Nickel -
Chrome - Molybdenum |
0.4 - 0.6
Ni, 0.4 - 0.6 Cr, 0.15 - 0.25 Mo |
| 92 |
Silicon |
1.8 - 2.2
Si |
Another system has also been developed by
American Iron and Steel Institute (AISI) for
Identifying the kind of furnace in which the
steel was made
B - Acid Bessemer Carbon Steel
C- Basic open-hearth or basic electric
furnace carbon steel.
E - Electric furnace alloy steel
CB - Either Bessemer or open hearth process
at option of the steel mill.
For e.g.
AISI C1018 is low carbon steel suited for
project work in wrought metal
Classification of steel according to number system
Number system:
A number system or series to identify carbon
and alloy steel had been developed by Society
of Automotive Engineers (SAE) and
American Iron and Steel Industry (AISI).
Steel are names based on their alloying elements
and carbon content. A 10 steel is plain carbon
steel. A 41 steel contains 0.4 - 1.1 %
Molybdenum, 0.08 - 0.35% Chromium. The system is
based on the use of numbers composed of four
digits.
The first 2 numbers refer to the alloying
elements present in that steel. First number
tells the kind of steel and the second number
shows the approximate percent of alloy elements.
For e.g.
2320 shows a nickel steel with about 3%
nickel. 41_ _ steel contains 0.4 -1.1% Molybdenum and
0.08 -0.35% Chromium.
The last 2 numbers shows the carbon content
in points (100 points equal 1 percent) For e.g. AISI C1095 or SAE 1095 is carbon steel with 95
points of carbon.
For e.g.
_ _18 steel had 0.18% carbon.
4118 contains 0.8 - 1.1% chromium and
0.15 - 0.25% molybdenum with 0.8% carbon.
Table of steels and their respective
numbers:
| Steel |
Number |
Range of
Number |
|
a) Carbon steel |
|
Carbon steel
SAE-AISI |
1XXX |
|
|
Plain Carbon |
10XX |
|
|
Free
machining (resulphurized) |
11XX |
|
|
Resulphrized,
rephosporised |
12XX |
|
| |
|
|
|
b) Alloy Steel |
|
|
| Manganese |
13XX |
|
| Molybdenum |
4XXX |
|
|
C-Mo(0.25% Mo) |
40XX |
|
|
CR-Mo(0.70% Cr, 0.15% Mo) |
41XX |
|
|
Ni-Cr-Mo(1.8% Ni, 0.65% CR) |
43XX |
|
|
Ni-Mo(1.75% Ni) |
46XX |
|
|
Ni-Cr(0.45% Ni, 0.2% Mo) |
47XX |
|
|
Ni-Mo(3.5%
Ni, 0.25% Mo) |
48XX |
|
| |
|
|
| Chromium |
5XXX |
|
|
0.5% Cr |
50XX |
|
|
1.0% Cr |
51XX |
5120-5152 |
|
1.5% Cr |
52XX |
52095-52100 |
|
Corrosion-heat resistant |
514XX |
(AISI 400
Series) |
| |
|
|
|
Chromium-Vanadium |
6XXX |
|
| 1% Cr, O.12% V |
61XX |
6120-6152 |
| |
|
|
| Silicon
Manganese |
|
|
| 0.85% Mn, 2%
Si |
92XX |
9255-9262 |
| |
|
|
| Triple-alloy
Steels |
|
|
| 0.55% Ni,
0.50% Cr, 0.20% Mo, |
86XX |
8615-8660 |
| 0.55% Ni,
0.50% Cr, 0.25% Mo |
87XX |
8720-8750 |
| 3.25% Ni, 1.2%
Cr, 0.12% Mo |
93XX |
9310-9317 |
| 0.45% Ni, 0.4%
Cr, 0.12% Mo |
94XX |
9437-9445 |
| 0.45% Ni,
0.15% Cr, 0.2% Mo |
97XX |
9747-9763 |
| 1.00 % Ni,
0.8% Cr, 0.25% Mo |
98XX |
9840-9850 |
| |
|
|
| Boron (~0.05%
Mn) |
XXBXX |
|
|
Boron is
denoted by addition of B. Boron-Vanadium
is denoted by addition of BV. 14 BXX, 50
BXX, 80 BXX. The letters appearing before
the number indicate the following.
A- Alloy-
basic open hearth
B-
Carbon-acid-Bessemer
C-
Carbon-Basic open hearth
D- Carbon
-acid open
E- Electric
furnace |
|
Stainless and
heat resisting steels
2XX - Chromium
nickel -manganese type
3XX-
Chromium-nickel types
4XX- Straight
chromium types
5XX- Low
chromium types
All stainless
steels are produced in electric furnace. |
|
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