Steel 1018 properties
Chemical composition
Section titled “Chemical composition”AISI 1018 steel contains a carbon percentage between 0.15 % and 0.20 % and manganese between 0.60 % and 0.90 %, which gives it good machinability and weldability. The nominal chemical composition is as follows.
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.15 – 0.20 |
| Manganese (Mn) | 0.60 – 0.90 |
| Phosphorus (P) | 0.04 max. |
| Sulfur (S) | 0.05 max. |
| Iron (Fe) | Balance |
Note: According to some specifications, the carbon content may vary between 0.14 % and 0.20 % and manganese between 0.30 % and 0.90 %.
Physical properties
Section titled “Physical properties”The density of 1018 steel is 7.87 g/cm³, a typical value for non-alloy carbon steels.
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.87 g/cm³ | 0.284 lb/in³ |
Mechanical properties (cold drawn)
Section titled “Mechanical properties (cold drawn)”In the cold drawn condition, the tensile strength of 1018 steel reaches 440 MPa. The representative mechanical properties are detailed below.
| Property | Metric | Imperial |
|---|---|---|
| Tensile strength | 440 MPa | 63 800 psi |
| Yield strength (0.2 %) | 370 MPa | 53 700 psi |
| Modulus of elasticity | 205 GPa | 29 700 ksi |
| Shear modulus | 80 GPa | 11 600 ksi |
| Poisson’s ratio | 0.29 | 0.29 |
| Elongation at break (50 mm) | 15 % | 15 % |
| Brinell hardness | 126 | 126 |
| Knoop hardness (converted) | 145 | 145 |
| Rockwell B hardness (converted) | 71 | 71 |
| Vickers hardness (converted) | 131 | 131 |
| Machinability (base AISI 1212 = 100 %) | 70 | 70 |
Mechanical properties (annealed)
Section titled “Mechanical properties (annealed)”The tensile strength of annealed 1018 is around 400 MPa, exhibiting notably higher ductility than in the drawn condition.
| Property | Metric | Imperial |
|---|---|---|
| Tensile strength | 400 MPa | 58 000 psi |
| Yield strength (0.2 %) | 221 MPa | 32 000 psi |
| Elongation at break (50 mm) | 25 % | 25 % |
| Brinell hardness | 116 | 116 |
Typical values for hot rolled material, comparable to the annealed condition.
Thermal properties
Section titled “Thermal properties”The thermal conductivity of 1018 steel is 51.9 W/m·K, which facilitates heat dissipation in machined components.
| Property | Metric | Imperial |
|---|---|---|
| Thermal conductivity | 51.9 W/m·K | 360 BTU·in/(h·ft²·°F) |
Other indicative properties (not from the sources consulted): coefficient of thermal expansion ≈ 11.5 × 10⁻⁶ /°C, specific heat ≈ 486 J/kg·°C.
Heat treatment
Section titled “Heat treatment”The recommended forging range is between 996 °C and 1260 °C (1825 – 2300 °F). Through case hardening, it is possible to achieve a hardness of 42 HRC in thin sections; in parts over 4 in (101 mm) the maximum hardness obtained ranges between 28 and 30 HRC. Full annealing is performed at 899 °C (1650 °F) followed by slow cooling in the furnace, while process annealing is carried out at 649 °C (1200 °F).
Machinability
Section titled “Machinability”The machinability of 1018 is rated at 70 % relative to AISI 1212 steel (100 %). It is also reported as 62 % relative to AISI 1112. It produces continuous and hard chips, and can be machined in any heat treatment condition, achieving a very fine surface finish.
Welding
Section titled “Welding”1018 steel is suitable for gas, oxyacetylene, resistance, and submerged arc welding. Due to its low carbon content, it usually does not require preheating, which simplifies joining operations.
Applications
Section titled “Applications”Thanks to its availability and excellent machinability, 1018 is primarily used for parts produced in large volumes on automatic lathes. Among the most common applications are:
- Shafts and transmission shafts
- Spindles and lead screws
- Pins and dowels
- Bars and rods
- Pinion and gear assemblies
- Low-load structural components
Comparison with similar materials
Section titled “Comparison with similar materials”The following table contrasts 1018 steel with other commonly used carbon steels, highlighting the differences in carbon content, strength, and machinability.
| Material | Carbon (%) | Tensile strength (MPa, cold drawn) | Machinability (%) | Main characteristic |
|---|---|---|---|---|
| AISI 1018 | 0.15 – 0.20 | 440 | 70 | Balance strength‑machinability |
| AISI 1020 | 0.18 – 0.23 | 450 | 60 – 65 | Slightly more carbon, lower machinability |
| AISI 1045 | 0.43 – 0.50 | 590 (quenched and tempered) | ≈ 55 | Higher hardenability, suitable for fatigue |
| AISI 12L14 | ≤ 0.15 | 490 | 160 | Extreme machinability (lead), poor weldability |
Machinability is referenced to the AISI 1212 standard (100 %); strength values may vary depending on manufacturer and heat treatment.
Frequently Asked Questions (FAQ)
Section titled “Frequently Asked Questions (FAQ)”What is the tensile strength of 1018 steel?
Section titled “What is the tensile strength of 1018 steel?”The tensile strength of cold drawn 1018 steel is 440 MPa (63.8 ksi). In the annealed condition it decreases to approximately 400 MPa (58 ksi).
What hardness does 1018 steel have?
Section titled “What hardness does 1018 steel have?”The Brinell hardness of cold drawn 1018 is 126 HB, equivalent to 71 HRB. The annealed version has a Brinell hardness of 116.
At what temperature is 1018 steel forged?
Section titled “At what temperature is 1018 steel forged?”Forging is performed in the range of 996 °C to 1260 °C (1825 – 2300 °F).
Can 1018 steel be welded?
Section titled “Can 1018 steel be welded?”Yes, the maximum carbon content of 0.20 % provides excellent weldability with all conventional methods (gas, MIG, TIG, resistance), without the need for special preheating.
What is the machinability of 1018 steel?
Section titled “What is the machinability of 1018 steel?”The machinability of 1018 is rated at 70 % relative to the reference steel AISI 1212 (100 %), making it a material suitable for series production.
What is the elongation of 1018 steel?
Section titled “What is the elongation of 1018 steel?”The elongation at break of cold drawn 1018 is 15 % (measured over 50 mm). In the annealed condition, ductility rises to 25 %.
References
Section titled “References”- azom.com: https://www.azom.com/article.aspx?ArticleID=9138
- engineeringtoolbox.com: https://www.engineeringtoolbox.com/compositions-steel-d_1494.html
- steelnumber.com: https://www.steelnumber.com/en/steel_composition_eu.php?name_id=688