1018 steel is one of the most common low-carbon steels used in CNC machining. It offers excellent machinability, stable cutting behavior, and low cost, making it ideal for shafts, pins, brackets, and general-purpose components. In the cold-drawn condition, 1018 typically has a tensile strength of ~440 MPa, yield strength ~370 MPa, and a machinability rating of 70–75% compared to B1112 free-machining steel.
Core Mechanical Properties of 1018 Steel
| Property | Typical Value | Note |
|---|---|---|
| Tensile Strength | ~440 MPa | Cold drawn |
| Yield Strength | ~370 MPa | Cold drawn |
| Hardness | 120–160 HB | Brinell |
| Elongation | 15–20% | Moderate ductility |
| Machinability | 70–75% | Relative to B1112 = 100% |
Comprehensive Engineering Data
| Condition | Tensile Strength (MPa) | Yield Strength (MPa) | Hardness (HB) | Elongation (%) | Fatigue Strength (MPa) | Shear Strength (MPa) |
|---|---|---|---|---|---|---|
| Hot Rolled | ~415 | ~345 | 110–150 | 20–25 | ~200–250 | ~250–275 |
| Cold Drawn | ~440 | ~370 | 120–160 | 15–20 | ~230–280 | ~260–290 |
Fatigue and shear values are derived from engineering handbooks using empirical ratios.
Chemical Composition of 1018 Steel
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.15–0.20 |
| Manganese (Mn) | 0.60–0.90 |
| Phosphorus (P) | ≤0.04 |
| Sulfur (S) | ≤0.05 |
| Iron (Fe) | Balance |
CNC Machining Precautions for 1018 Steel
1018 steel is regarded as one of the easiest steels to machine. In cold-drawn form, it provides dimensional stability and cleaner finishes compared to hot-rolled material. Carbide or coated HSS tools perform well, and tool life is generally 20–30% longer than when machining alloy steels such as 4140, making it attractive for high-volume production.
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Tolerances: ±0.01 mm achievable with CNC turning or milling.
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Surface Finish: Ra 1.6 µm typical; Ra <0.4 µm possible after grinding.
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Productivity: High feed rates possible without excessive tool wear, improving cost efficiency.
1018 Welding Precautions
1018 steel is highly weldable due to its low carbon content. Most welding processes (MIG, TIG, stick) can be applied without preheating. For thick sections, preheating to around 150 °C helps reduce residual stresses. Low-hydrogen electrodes are recommended for structural applications.
Surface Treatments
Because 1018 is relatively soft and lacks corrosion resistance, engineers often specify surface treatments:
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Carburizing: Surface hardness up to HRC 55–60 with a ductile core.
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Zinc Plating / Galvanizing: Corrosion protection for outdoor use.
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Black Oxide: Light corrosion resistance, uniform black finish.
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Powder Coating / Painting: Environmental and cosmetic protection.
Extended Applications
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Automotive: mounting brackets, bushings, pins, and fasteners that do not require alloy steel strength.
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Construction Machinery: support plates, hinge pins, and low-stress structural parts where machinability and low cost are key.
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Agricultural Equipment: shafts, couplings, and linkages that are easy to machine and repair in the field.
1018 is typically selected for components that need reliable machinability and reasonable strength, but are not subjected to high fatigue or wear loads.
Design Example
For a 10 mm diameter 1018 steel dowel pin in cold-drawn condition (~370 MPa yield strength):
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Cross-sectional area = 78.5 mm²
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Yield load = 370 MPa × 78.5 mm² = 29,000 N (~2.9 tons)
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With a safety factor of 3 → usable working load ~1 ton
Heat Treatment Limitations
1018 steel cannot be significantly hardened by direct quenching because its carbon content is too low. Quenching results in minimal martensite formation, leaving the hardness nearly unchanged. Instead, surface-hardening methods such as carburizing or carbonitriding are commonly used. These create a hard outer layer (HRC 55–60) for wear resistance, while the core remains soft and ductile. This combination makes 1018 suitable for components like gears, pins, and shafts that need a tough interior with a hard surface.
Machining Economy Comparison
| Material | Machinability (%) | Cutting Speed (m/min) | Tool Life (relative) | Material Cost |
|---|---|---|---|---|
| 1018 Steel | 70–75 | 90–150 | 100% baseline | Low |
| 1045 Steel | ~65 | 70–120 | ~80% of 1018 | Medium |
| 4140 Steel | 55–65 | 50–90 | ~60% of 1018 | Medium–High |
This table highlights why 1018 is preferred for mass production: faster cutting speeds, longer tool life, and lower material cost.
Comparison: 1018 vs 1045 vs 4140
| Property | 1018 Steel | 1045 Steel | 4140 Steel |
|---|---|---|---|
| Tensile Strength | ~440 MPa | ~620 MPa | 850–1100 MPa |
| Yield Strength | ~370 MPa | ~450 MPa | 655–950 MPa |
| Hardness | 120–160 HB | 170–210 HB | 32–45 HRC |
| Elongation | 15–20% | 12–16% | 12–16% |
| Machinability | 70–75% | ~65% | 55–65% |
| Cost | Low | Medium | Medium–High |
| Typical Use | Brackets, pins, supports | Stronger shafts, gears | High-strength gears, fatigue parts |
Engineering Perspective
From a design standpoint, 1018 is best for parts that require ease of machining and cost efficiency. For structural loads, a safety factor of 2–3 is essential due to its relatively low yield strength. Fatigue stress should be kept below 200 MPa for long service life. In production, its machining efficiency reduces cycle times and extends tool life, making it one of the most economical steels for CNC machining. For wear resistance, carburizing is the most effective way to extend durability.
JeekRapid Services
JeekRapid provides CNC machining of 1018 steel parts for automotive, construction machinery, and agricultural applications. Services include precision turning and milling, surface finishing, and surface hardening treatments such as carburizing and galvanizing.Recently we delivered 500 pcs of carburized 1018 pins for an agricultural machinery client, tolerance ±0.01 mm and surface hardness 58 HRC.
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