Carbon steels are iron-carbon alloys containing up to 2.06% of carbon, up to 1.65% of manganese, up to 0.5% of silicon and sulfur and phosphorus as impurities.
The higher carbon content, the higher steel strength and the lower its ductility.
According to the steels classification there are following groups of carbon steels:
- Low carbon steels (C < 0.25%)
- Medium carbon steels (C =0.25% to 0.55%)
- High carbon steels (C > 0.55%)
Designation system of carbon steels
Chemical compositions of some carbon steels
Properties of some carbon steels
Chemical compositions of some carbon steels
Properties of some carbon steels
Properties: good formability and weldability, low strength, low cost.
Applications: deep drawing parts, chain, pipe, wire, nails, some machine parts.
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Properties: good toughness and ductility, relatively good strength, may be hardened by quenching
Applications: rolls, axles, screws, cylinders, crankshafts, heat treated machine parts.
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Properties: high strength, hardness and wear resistance, moderate ductility.
Applications: rolling mills, rope wire, screw drivers, hammers, wrenches, band saws.
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Properties: very high strength, hardness and wear resistance, poor weldability low ductility.
Applications: punches, shear blades, springs, milling cutters, knives, razors.
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American Iron and Steel Institute (AISI) together with Society of Automotive Engineers (SAE) have established four-digit (with additional letter prefixes) designation system:
SAE 1XXX
First digit 1 indicates carbon steel (2-9 are used for alloy steels);
Second digit indicates modification of the steel.
0 - Plain carbon, non-modified
1 - Resulfurized
2 - Resulfurized and rephosphorized
5 - Non-resulfurized, Mn over 1.0%
Last two digits indicate carbon concentration in 0.01%.
Example: SAE 1030 means non modified carbon steel, containing 0.30% of carbon.
A letter prefix before the four-digit number indicates the steel making technology:
A - Alloy, basic open hearth
B - Carbon, acid Bessemer
C - Carbon, basic open hearth
D - Carbon, acid open hearth
E - Electric furnace
Example: AISI B1020 means non modified carbon steel, produced in acid Bessemer and containing 0.20% of carbon.
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SAE/AISI grade | C, % | Mn,% | P,% max | S,% max |
0.08 max | 0.35 max | 0.04 | 0.05 | |
0.08-0.13 | 0.30-0.60 | 0.04 | 0.05 | |
0.17-0.23 | 0.30-0.60 | 0.04 | 0.05 | |
0.27-0.34 | 0.60-0.90 | 0.04 | 0.05 | |
0.42-0.50 | 0.60-0.90 | 0.04 | 0.05 | |
0.65-0.76 | 0.60-0.90 | 0.04 | 0.05 | |
0.85-0.98 | 0.60-0.90 | 0.04 | 0.05 | |
0.14-0.20 | 1.10-1.30 | 0.04 | 0.08-0.13 | |
0.43-0.51 | 1.35-1.65 | 0.04 | 0.05 |
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