Jul 5 2012
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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.