AISI 1018 Low Carbon Steel Bar

Product Overview

1018 steel is the most widely used mild low carbon steel grade in global machining and metal fabrication industries, also known as AISI 1018 carbon steel round bar, UNS G10180 material complying with ASTM A108 standard. Our factory supplies full series hot rolled 1018 steel rod and cold drawn 1018 bright round bar, with strictly controlled chemical composition to guarantee stable mechanical performance, outstanding machinability, perfect weldability and superior cold forming capacity.

The "10" designation identifies this as a carbon-manganese steel series, while "18" indicates an average carbon content of approximately 0.18% . With a slightly elevated manganese content compared to other low-carbon grades such as 1020, 1018 steel offers improved hardenability, enhanced mechanical properties, and superior case hardening response. After carburizing heat treatment, it can form hard wear-resistant surface while retaining tough core, making it the top choice for precision mechanical components that need surface hardening.

Steel Equivalent Grades

Product Features

Chemical Composition

Mechanical Properties

• Tensile Strength: 440-485 MPa

• Yield Strength: 370-415 MPa

• Elongation: 30% min

• Reduction of Area: 40%

• Brinell Hardness (HB): 126-143; up to 55 HRC after carburizing

• Modulus of Elasticity: 200-205 GPa

Heat Treatment and Case Hardening

1018 carbon steel responds favorably to carburizing (case hardening) methods, making it particularly suitable for components requiring high surface hardness combined with a tough, ductile core.

Carburizing Process:

• Carburize at 1650–1700°F for approximately 8 hours

• Cool in oven and reheat to 1400–1450°F

• Quench in water and draw at 300–350°F

• Typical carburizing depth: 0.060–0.070 inches

Heat Treatment

• Forging: Heat to 1175–1230°C

• Normalizing: Heat to 900–1230°C, cool in air

• Annealing: Heat to 840–900°C, cool in furnace

The elevated manganese content in 1018 produces a harder and more uniform case than lower-manganese grades, enhancing wear resistance in carburized parts.

Supply Size & Tolerance

1. Size Range

2. Surface Finish & Tolerance

Machinability and Weldability

Machinability

1018 carbon steel offers excellent machining characteristics, rated at approximately 78% of B1112 (based on AISI 1212 as 100%). This favorable rating translates to reduced tool wear, efficient chip formation, and superior surface finish during drilling, turning, threading, and milling operations. The cold drawing process further enhances machinability by improving dimensional accuracy and surface quality .

Weldability

This grade demonstrates excellent weldability across all standard welding processes, including gas, arc, and submerged arc welding. The resultant welds and joints exhibit extremely high quality without requiring preheating or post-weld heat treatment for most thicknesses. The low carbon equivalent minimizes the risk of weld-zone hardening, making 1018 a reliable choice for fabricated assemblies

Main Applications

1018 steel is a universal low carbon structural steel widely applied across dozens of industries, covering high-frequency search scenarios like "1018 steel for CNC parts", "1018 steel automotive components":

Machinery Manufacturing

Precision shafts, positioning pins, connecting rods, spindles, bearing seats, jig fixtures, transmission gear blanks, small worm gears, dowel pins, cam parts. Machine shops prefer 1018 round bar for mass CNC production due to low tool loss and stable machining performance.

Automotive Industry

Carburized gear parts, engine brackets, control arm pins, shift forks, axle sleeves, fastener blanks, vehicle chassis small structural accessories, motorcycle sprockets and shafts.

Fastener & Hardware Production

Bolt, nut, screw, rivet, stud, self-tapping screw raw material; hand tool blanks like wrenches, screwdriver shafts, metal hardware fittings.

General Fabrication & Construction

Welded frame assemblies, support brackets, pipe connectors, agricultural machinery parts, conveyor roller shafts, light structural components for factory equipment.

Household Appliance & Electronics

Washing machine internal shafts, refrigerator support parts, small metal structural frames, low-load stamping components requiring bending forming.

1018 Steel vs 1045 Steel vs A36 Steel Grades

1018 VS 1045 Medium Carbon Steel

• 1018 steel: Lower carbon, better weld & form performance, suitable for carburizing surface hardening, low hardness raw blank.

• 1045 steel: Higher carbon, higher raw hardness, good tensile strength, cannot be easily carburized, used for high-strength shafts without surface wear demand.

1018 VS A36 Structural Steel

• 1018 steel: Uniform composition, superior machinability, strict diameter tolerance, designed for precision machining.

• A36 steel: Focus on building welding structure, poor machining performance, large dimensional tolerance, not fit for CNC precision parts.

FAQ

Q1: What is the difference between 1018 and 1020 carbon steel?

A1: The main difference lies in carbon content. 1018 steel contains 0.15%–0.20% carbon, while 1020 steel contains 0.18%–0.23% carbon. This slightly higher carbon content gives 1020 marginally higher strength and hardness, but 1018 offers better machinability, superior surface finish after machining, and improved cold forming characteristics. For most precision machining applications, 1018 is the preferred choice due to its more consistent machinability and better dimensional stability.

Q2: How does manganese content affect 1018 steel performance?

A2: The manganese content in 1018 steel ranges from 0.60% to 0.90%, which is slightly elevated compared to other low-carbon steels. This higher manganese level improves the steel's tensile strength, hardenability, and wear resistance, while also helping to deoxidize the melt and reduce brittleness. Additionally, the manganese content contributes to a more uniform and harder case during carburizing, making 1018 particularly suitable for wear-resistant applications where a tough core is required.

Q3: Can 1018 steel be heat treated or case hardened?

A3: Yes, 1018 steel responds very favorably to case hardening (carburizing) processes. While its low carbon content limits through-hardening capability, the elevated manganese content produces a harder and more uniform case than lower-manganese grades. Typical carburizing involves heating to 1650–1700°F (900–925°C), followed by quenching and tempering, achieving surface hardness with a tough, ductile core—ideal for gears, pins, and wear-resistant components.

Q4: What are the mechanical properties of 1018 cold-rolled steel?

A4: For cold-drawn 1018 carbon steel, typical mechanical properties include: ultimate tensile strength of 440–485 MPa (64,000–70,300 psi), yield strength of 370–415 MPa (54,000–60,200 psi), elongation at break of 15%–18% in 50 mm, and Brinell hardness ranging from 126 to 143. These properties make it suitable for medium-strength applications requiring both toughness and formability.

For detailed specifications, custom sizes, or technical consultation on 1018 carbon steel products, please contact us.