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The OnlineMetals Guide to Steel
Steel is a term used for iron to which between 0.02 to 1.7% carbon has been added. The old definition of steel
used to be something like "it rusts and it sinks in water." This material comprises the most diverse group
of alloys and applications in the metals world. If there is something that needs to be made, there probably is a
steel alloy that it can be made of. Steel does, of course, have poor corrosion resistance, but its relatively low cost
and ease of painting make it a common choice.
The numbering system for steel is actually one of the few things in the metals industry that seems to make sense. You
can determine the alloying ingredients by the first two digits of the alloy number, and the carbon content by the last
two digits. For instance, 1018 is simply iron with a carbon content of 0.18%. Generally speaking, as the carbon content
goes up, strength increases, but machinability and weldability decrease.
OnlineMetals.com currently stocks six grades of steel in various shapes and sizes:
| 1018 Steel |
(available in Rectangle, Rectangle, Round, Square, Square) |
| A36 Steel |
(available in Angle, Perforated Sheet, Plate, Rectangle, Rectangle Tube, Rectangle Tube, Round, Square, Square Tube) |
| 1144 Steel |
(available in Round) |
| 12L14 Steel |
(available in Round) |
| A653 Steel |
(available in Sheet) |
| A366/1008 Steel |
(available in Sheet) |
| A513 Steel |
(available in Tube) |
1018 Mild Steel
Alloy 1018 is the most commonly available of the cold-rolled steels. It is generally available in round rod,
square bar, and rectangle bar. It has a good combination of all of the typical traits of steel - strength, some ductility,
and comparative ease of machining. Chemically, it is very similar to A36 Hot Rolled steel, but the cold rolling process
creates a better surface finish and better properties.
| 1018 Mild (low-carbon) steel |
| Minimum Properties |
Ultimate Tensile Strength, psi |
63,800 |
| Yield Strength, psi |
53,700 |
| Elongation |
15.0% |
| Rockwell Hardness |
B71 |
| Chemistry |
Iron (Fe) |
98.81 - 99.26% |
| Carbon (C) |
0.18% |
| Manganese (Mn) |
0.6 - 0.9% |
| Phosphorus (P) |
0.04% max |
| Sulfur (S) |
0.05% max |
A36 Mild Steel
ASTM A36 steel is the most commonly available of the hot-rolled steels. It is generally available in round rod,
square bar, rectangle bar, as well as steel shapes such as I-Beams, H-beams, angles, and channels. The hot roll
process means that the surface on this steel will be somewhat rough. Note that its yield strength is also significantly
less than 1018 - this means that it will bend much more quickly than will 1018. Finally, machining this material is
noticeably more difficult than 1018 steel, but the cost is usually significantly lower.
| ASTM A36 Mild (low-carbon) steel |
| Minimum Properties |
Ultimate Tensile Strength, psi |
58,000 - 79,800 |
| Yield Strength, psi |
36,300 |
| Elongation |
20.0% |
| Chemistry |
Iron (Fe) |
99% |
| Carbon (C) |
0.26% |
| Manganese (Mn) |
0.75% |
| Copper (Cu) |
0.2% |
| Phosphorus (P) |
0.04% max |
| Sulfur (S) |
0.05% max |
1144 (Stressproof-equivalent) steel
This material is actually pretty cool, at least for steel. It is a higher-strength alloy than 1018 or A36, but in addition has
improved ductility as well. The chief feature of 1144 steel, however, is that it has very low distortion or warpage after
machining due to a combination of its chemistry, method of manufacture, and heat treatment.
Finally, 1144 is relatively easy to machine, with a machinability rating of 83% of AISI 1212 steel.
| 1144 (Stressproof-equivalent) steel |
| Minimum Properties |
Ultimate Tensile Strength, psi |
115,000 |
| Yield Strength, psi |
100,000 |
| Elongation |
8.0% |
| Rockwell Hardness |
B95 / C17 |
| Chemistry |
Iron (Fe) |
97.54 - 98.01% |
| Carbon (C) |
0.4 - 0.44% |
| Manganese (Mn) |
1.35 - 1.65% |
| Phosphorus (P) |
0.04% max |
| Sulfur (S) |
0.24 - 0.33% |
12L14 free machining steel
This alloy has lead added to the mix in order to enhance its machinability. In fact, it is rated with a machinability of 160% of
AISI 1212 steel. The addition of lead does, however, reduce the strength of this alloy, although it is generally stronger than 1018.
| 12L14 free machining steel |
| Minimum Properties |
Ultimate Tensile Strength, psi |
78,300 |
| Yield Strength, psi |
60,200 |
| Elongation |
10.0% |
| Rockwell Hardness |
B84 |
| Chemistry |
Iron (Fe) |
97.91 - 98.7% |
| Carbon (C) |
0.15% max |
| Manganese (Mn) |
0.85 - 1.15% |
| Phosphorus (P) |
0.04 - 0.09% |
| Lead (Pb) |
0.15 - 0.35% |
| Sulfur (S) |
0.26 - 0.35% |
A653 Galvanized Steel
Galvanized steel is simply hot rolled steel to which a zinc coating has been applied for protection against corrosion.
| ASTM A653 Mild (low-carbon) Hot Dipped Galvanized Steel |
| Minimum Properties |
Ultimate Tensile Strength, psi |
58,000 - 79,800 |
| Yield Strength, psi |
36,300 |
| Elongation |
20.0% |
| Chemistry |
Iron (Fe) |
99% |
| Carbon (C) |
0.26% |
| Manganese (Mn) |
0.75% |
| Copper (Cu) |
0.2% |
| Phosphorus (P) |
0.04% max |
| Sulfur (S) |
0.05% max |
A366/1008 Steel
This alloy is generally used for "commercial quality" cold rolled steel sheet. It is known for its very good formability
and comparatively high strength. It has a very good surface finish that is far superior to hot rolled A36.
| ASTM A366 (alloy 1008) steel |
| Minimum Properties |
Ultimate Tensile Strength, psi |
43,900 - 51,900 |
| Yield Strength, psi |
26,100 - 34,800 |
| Elongation |
42 - 48% |
| Chemistry |
Iron (Fe) |
99% |
| Carbon (C) |
0.08% |
| Manganese (Mn) |
0.6% max |
| Phosphorus (P) |
0.035% max |
| Copper (Cu) |
0.2% min |
| Sulfur (S) |
0.04% |
A513 (alloy 1020-1026) Steel
This alloy is generally used for DOM tubing. Its higher carbon content means higher strength, but lower weldability
and machinability.
| ASTM A513 alloys 1020 - 1026 Mild (low-carbon) steel |
| Minimum Properties |
Ultimate Tensile Strength, psi |
87,000 |
| Yield Strength, psi |
72,000 |
| Elongation |
10.0% |
| Rockwell Hardness |
B89 |
| Chemistry |
Iron (Fe) |
99.08 - 99.53% |
| Carbon (C) |
0.18 - 0.23% |
| Manganese (Mn) |
0.3 - 0.6% |
| Phosphorus (P) |
0.04% max |
| Sulfur (S) |
0.05% max |
At OnlineMetals, we all failed shop class. Multiple times. As a matter of fact, our employment applications
specifically ask to see people's grades for their high school shop classes. If they're too high, they go
into the rejected pile. We're also not engineers, and cannot make any specific recommendations about the suitability
of a given alloy, temper, or shape for your project or application.
All technical data is for comparison purposes only and is NOT FOR DESIGN. It has been compiled
from sources we believe to be accurate but cannot guarantee. This ends the part of the website
that our pointy-headed lawyers made us put in.
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