Editorial Feature

AISI 1018 Mild/Low Carbon Steel

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AISI 1018 mild/low carbon steel has excellent weldability, produces a uniform and harder case and it is considered the best steel for carburized parts. AISI 1018 mild/low carbon steel offers a good balance of toughness, strength and ductility. AISI 1018 hot rolled steel has significant mechanical properties, improved machining characteristics and has a high Brinell hardness measure.

Specific manufacturing controls are used for surface preparation, chemical composition, rolling and heating processes. All these processes develop a supreme quality product that is suited to fabrication processes such as welding, forging, drilling, machining, cold drawing and heat treating.

Chemical Composition

Element Content
Carbon, C 0.14 - 0.20 %
Iron, Fe 98.81 - 99.26 % (as remainder)
Manganese, Mn 0.60 - 0.90 %
Phosphorous, P ≤ 0.040 %
Sulfur, S ≤ 0.050 %

Physical Properties

Physical Properties Metric Imperial
Density 7.87 g/cc 0.284 lb/in3

Mechanical Properties

Mechanical Properties Metric Imperial
Hardness, Brinell 126 126
Hardness, Knoop (Converted from Brinell hardness) 145 145
Hardness, Rockwell B (Converted from Brinell hardness) 71 71
Hardness, Vickers (Converted from Brinell hardness) 131 131
Tensile Strength, Ultimate 440 MPa 63800 psi
Tensile Strength, Yield 370 MPa 53700 psi
Elongation at Break (In 50 mm) 15.0 % 15.0 %
Reduction of Area 40.0 % 40.0 %
Modulus of Elasticity (Typical for steel) 205 GPa 29700 ksi
Bulk Modulus (Typical for steel) 140 GPa 20300 ksi
Poissons Ratio (Typical For Steel) 0.290 0.290
Machinability (Based on AISI 1212 steel. as 100% machinability) 70 % 70 %
Shear Modulus (Typical for steel) 80.0 GPa 11600 ksi

Electrical Properties

Electrical Properties Metric English Comments
Electrical resistivity @0°C (32°F) 0.0000159 Ω-cm 0.0000159 Ω-cm annealed condition
@100 °C/ 212 °F 0.0000219 Ω-cm 0.0000219 Ω-cm annealed condition
@ 200 °C/392 °F 0.0000293 Ω-cm 0.0000293 Ω-cm annealed condition

Machining

The machinability of AISI 1018 mild/low carbon steel is graded at 78% of B1112.

Weldability

AISI 1018 mild/low carbon steel can be instantly welded by all the conventional welding processes. Welding is not recommended for AISI 1018 mild/low carbon steel when it is carbonitrided and carburized.

Low carbon welding electrodes are used in the welding procedure. Post-heating and pre-heating are not necessary, although pre-heating can be performed for sections over 50 mm. Post-weld stress-relieving also has benefits, like the pre-heating process.

Heat Treatment

The heat treatment for AISI 1018 mild/low carbon steel consists of the following processes:

  • Normalizing - AISI 1018 mild/low carbon steel should be heated at 890°C – 940°C and then cooled in still air.
  • Forging - This process requires heating at 1150°C - 1280°C and AISI 1018 mild/low carbon steel is held until the temperature becomes constant. 900°C is the minimum temperature required for the forging process. The steel is cooled in air after this process.
  • Tempering - AISI 1018 mild/low carbon steel is tempered at 150°C – 200°C to improve case toughness. This process has little or no effect on hardness. Grinding cracks are reduced when AISI 1018 mild/low carbon steel is tempered.
  • Annealing - The AISI 1018 mild/low carbon steel is heated at 870°C – 910°C and allowed to cool in a furnace.
  • Stress Relieving – A temperature of 500°C – 700°C is required to relieve stress in AISI 1018 mild/low carbon steel that is later cooled down in still air.
  • Case Hardening - This process requires heating to be carried out between 780°C – 820°C. AISI 1018 mild/low carbon steel is then quenched in water.
  • Core Refining - This is an optional process that requires heating at 880°C – 920°C. After being heated, AISI 1018 mild/low carbon steel is moistened in oil or water.
  • Carburizing – This process takes place at 880°C – 920°C for AISI 1018 mild/low carbon steel. It is used in bending, crimping and swaging processes and is widely used for fixtures, mounting plates and spacers and in applications that do not need high alloy steel and high carbon strength. Carburized parts that include worms, gears, pins, dowels, non-critical components of tool and die sets, tool holders, pinions, machine parts, ratchets, dowels and chain pins use AISI 1018 mild/low carbon steel.

Carburized steel provides high surface hardness and a soft core to parts that include worms, dogs, pins, liners, machinery parts, special bolts, ratchets, chain pins, oil tool slips, tie rods, anchor pins, studs etc. It is used to improve drilling, machining, threading and punching processes and prevent cracking in severe bends.

This article was updated on 7th August, 2019.

Comments

  1. Norm Nicholson Norm Nicholson Canada says:

    Anyone with experience welding cast steel and 1018 together? Pre-post heat, rod, wire to use?
      
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    • Clinton Wright Clinton Wright United States says:

      I would weld it with P9 mild steel rod. Don't use Wire so I can't help with that. TIG I would again use mild steel rods.

  2. alok kumar alok kumar India says:

    What is the steeling Density of MS 1018.

  3. Kevin Smith Kevin Smith Canada says:

    Wondering what material would be best to make a 4" long bottle/can opener with CNC machining?  How would that be case hardened to provide wear resistace, and would this process of hardening be after or before machining without resulting a change in dimensions?  Or is there a better "finishing" operation that would provide good wear resistance after machining the part?  Like nitriding or carborising.  I am totally lost how to go about this and where to start.  I am just a beginner trying to learn the ropes, but common sense tells me that it would be hard to machine a part that has been case hardened or heat treated, right?  Any comment and/or suggestion is appreciated.

  4. madan lal madan lal India says:

    can anyone suggest me the time duration and temperature for annealing 1018 3.5mm wire for best result?

  5. madan lal madan lal India says:

    can anyone guide with annealing process of 1018 mild steel drawn wire 3.5mm with temperature details and soaking period?

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of AZoM.com.

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