Carbon Steel
Low carbon steels generally contain less than 0.25% carbon and cannot be strengthened by heat-treating (strengthening can only be accomplished through cold working). The low carbon material is relatively soft and weak, but has outstanding ductility and toughness. In addition, it is machineable, weld-able, and is relatively inexpensive to produce.
Medium carbon steels have carbon concentrations between 0.25% and 0.60%. These steels may be heat-treated by austenizing, quenching, and then tempering to improve their mechanical properties. On a strength-to-cost basis, the heat-treated medium carbon steels provide tremendous load carrying ability.
An iron-based mixture is considered to be an alloy steel when manganese is greater than 1.65%, silicon over 0.5%, copper above 0.6%, or other minimum quantities of alloying elements such as chromium, nickel, molybdenum, vanadium, or tungsten are present. An enormous variety of distinct properties can be created for the steel by substituting these elements in the recipe to increase hardness, strength, or chemical resistance.
1) Principal Design Features & Applications:
| Low Carbon Steels – Principal Design Features & Applications | |||
|---|---|---|---|
| Alloy | UNS Designation | Principal Design Features | Applications |
| 1010 | G10100 | 1010 is a plain carbon steel with a nominal 0.10% carbon content. It is a relatively low strength steel, but it may be quenched and tempered for increased strength. | Used for applications such as cold headed fasteners and bolts. |
| 1018 | G10180 | 1018 is among the most available grades in the world. Despite its unimpressive mechanical properties, the alloy is easily formed, machined, welded, and fabricated. Due to its higher manganese content, it can, in thin sections, be hardened to RC 42. | Often employed in high volume screw machine parts applications, such as shafts, spindles, pins, rods, sprocket assemblies, and an incredibly wide variety of component parts. |
| 1020 | G10200 | 1020 is a commonly used plain carbon steel. It has a nominal carbon content of 0.20% with approximately 0.50% manganese. It has a good combination of strength and ductility and may be hardened and carburized. | Used for simple structural applications such as cold formed fasteners and bolts. It is often used in the case hardened condition. |
| 1022 | G10220 | 1022 has a slightly higher carbon and manganese content plain carbon steel than 1020. It is used for its somewhat greater strength while still having good ductility. | Used for moderate strength structural applications such as cold formed fasteners and bolts. It is often used in the case hardened condition. |
| Medium Carbon Steels – Principal Design Features & Applications | |||
|---|---|---|---|
| Alloy | UNS Designation | Principal Design Features | Applications |
| 1030 | G10300 | 1030 is a higher carbon (0.30%) manganese steel in the plain carbon steel alloy family. It provides greater strength than the lower grades while still retaining reasonable ductility. | Generally used in the quenched and tempered condition for strength. Applications include machinery parts where strength and hardness are requisite. |
| 1040 | G10400 | 1040 has a higher (0.40%) carbon content for greater strength than the lower carbon alloys. It is hardenable by heat treatment, quench and tempering to develop 150 to 250 ksi tensile strength. | Used for crankshafts, couplings, and cold headed parts. |
| 1045 | G10450 | 1045 is a medium carbon steel used when greater strength and hardness is desired than in the rolled condition. | Used in gears, shafts, axles, bolts, studs, and machine parts. |
| 1060 | G10600 | 1060 is one of the higher carbon content (0.60%) steels. It is more difficult to fabricate than the lower carbon grades. | Used for hand tools such as screwdrivers, pliers, and similar items. |
| Alloy Steel – Principal Design Features & Applications | |||
|---|---|---|---|
| Alloy | UNS Designation | Principal Design Features | Applications |
| 4130 | G41300 | 4130 is a low alloy steel containing molybdenum and chromium as strengthening agents. The carbon content is nominally 0.30%, and with this relatively low carbon content, the alloy is excellent from the fusion weldability standpoint. The alloy can be hardened by heat treatment. | Used in structural applications such as aircraft engine mounts and welded tubing applications. |
| 4140 | G41400 | 4140 is one of the chromium, molybdenum, manganese alloy steels noted for toughness, good torsional strength, and good fatigue strength. | Used in a tremendous variety of applications. |
| 4340 | G43400 | 4340 is a heat treatable, low alloy steel containing nickel, chromium, and molybdenum. It is known for its toughness and capability of developing high strength in the heat treated condition, while retaining good fatigue strength. | Typically used for aircraft landing gear, power transmission gears and shafts, and other structural parts. |
2) Chemical Properties:
| Low Carbon Steels – Chemical Properties | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Alloy | UNS Designation | C (max) | Mn (max) | P (max) | S (max) | Si | Cr | Ni | Mo |
| 1010 | G10100 | 0.08-0.13% | 0.30-0.60% | 0.04% | 0.05% | – | – | – | – |
| 1018 | G10180 | 0.15-0.20% | 0.60-0.90% | 0.04% | 0.05% | – | – | – | – |
| 1020 | G10200 | 0.18-0.23% | 0.30-0.60% | 0.04% | 0.05% | – | – | – | – |
| 1022 | G10220 | 0.18-0.23% | 0.70-1.00% | 0.04% | 0.05% | – | – | – | – |
| Medium Carbon Steel Chemical Properties | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Alloy | UNS Designation | C (max) | Mn (max) | P (max) | S (max) | Si | Cr | Ni | Mo |
| 1030 | G10300 | 0.28-0.34% | 0.60-0.90% | 0.04% | 0.05% | – | – | – | – |
| 1040 | G10400 | 0.37-0.44% | 0.60-0.90% | 0.04% | 0.05% | – | – | – | – |
| 1045 | G10450 | 0.43-0.50% | 0.60-0.90% | 0.04% | 0.05% | – | – | – | – |
| 1060 | G10600 | 0.55-0.65% | 0.60-0.90% | 0.04% | 0.05% | – | – | – | – |
| Alloy Steel Chemical Properties | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Alloy | UNS Designation | C (max) | Mn (max) | P (max) | S (max) | Si | Cr | Ni | Mo |
| 4130 | G41300 | 0.28-0.33% | 0.40-0.60% | 0.035% | 0.04% | 0.15-0.35% | 0.80-1.10% | — | 0.15-0.25% |
| 4140 | G41400 | 0.38-0.43% | 0.75-1.00% | 0.035% | 0.04% | 0.15-0.35% | 0.80-1.10% | — | 0.15-0.25% |
| 4340 | G43400 | 0.38-0.43% | 0.60-0.80% | 0.035% | 0.04% | 0.15-0.35% | 0.70-0.90% | 1.65-2.00% | 0.20-0.30% |
3) Mechanical Properties:
Low Carbon Steels – Mechanical Properties:
Low carbon steels are relatively soft and weak, but have outstanding ductility and toughness. In addition, they are machinable, weldable, and are relatively inexpensive to produce.
| Alloy | UNS Designation | Typical Mechanical Properties | ||||
|---|---|---|---|---|---|---|
| Tensile (ksi) | Yield (ksi) | Elongation (% in 2″) | Reduction of Area (%) | Brinell Hardness | ||
| 1010 | G10100 | 53 | 44 | 20 | 40 | 105 |
| 1018 | G10180 | 64 | 54 | 15 | 40 | 126 |
| 1020 | G10200 | 64 | 54 | 24 | 54 | 126 |
| 1022 | G10220 | 69 | 58 | 15 | 40 | 137 |
Medium Carbon Steels – Mechanical Properties:
Medium carbon steels may be heat-treated by austenizing, quenching, and then tempering to improve their mechanical properties. On a strength-to-cost basis, the heat-treated medium carbon steels provide tremendous load carrying ability.
| Alloy | UNS Designation | Typical Mechanical Properties | ||||
|---|---|---|---|---|---|---|
| Tensile (ksi) | Yield (ksi) | Elongation (% in 2″) | Reduction of Area (%) | Brinell Hardness | ||
| 1030 | G10300 | 76 | 64 | 12 | 35 | 149 |
| 1040 | G10400 | 90 | 80 | 12 | 35 | 170 |
| 1045 | G10450 | 91 | 77 | 12 | 35 | 179 |
| 1060 | G10600 | 118 | 70 | 17 | 34 | 241 |
Alloy Steels – Mechanical Properties:
An enormous variety of distinct properties can be created for alloy steel by substituting the chemical elements in the recipe to increase hardness, strength, or chemical resistance.
| Alloy | UNS Designation | Typical Mechanical Properties | ||||
|---|---|---|---|---|---|---|
| Tensile (ksi) | Yield (ksi) | Elongation (% in 2″) | Reduction of Area (%) | Brinell Hardness | ||
| 4130 | G41300 | 80 | 56 | 28 | 57 | 149 |
| 4140 | G41400 | 150 | 90 | 20 | 45 | 285 |
| 4340 | G43400 | 110 | 66 | 23 | 49 | 197 |