Introduction
AISI 1018 mild/low carbon steel has excellent weldability and produces a uniform and harder case and it is considered as the best steel for carburized parts. AISI 1018 mild/low carbon steel offers a good balance of toughness, strength and ductility. Provided with higher mechanical properties, AISI 1018 hot rolled steel also includes improved machining characteristics and Brinell hardness.
Specific manufacturing controls are used for surface preparation, chemical composition, rolling and heating processes. All these processes develop a supreme quality product that are 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 to be used in the welding procedure, and post-heating and pre-heating are not necessary. Pre-heating can be performed for sections over 50 mm. Post-weld stress relieving also has its own beneficial aspects like the pre-heating process.
Heat Treatment
The heat treatment for AISI 1018 mild/low carbon steel consists of the following processes:
Normalizing
Forging
This process requires heating between 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 then cooled in air after this process.
Tempering
AISI 1018 mild/low carbon steel is tempered at between 150°C – 200°C for improvement of case toughness. This process has little or no effect on hardness.
The occurrence of grinding cracks is reduced when AISI 1018 mild/low carbon steel is tempered at the above mentioned temperature.
Annealing
Stress Relieving
Case Hardening
Core Refining
Carburizing
Applications of AISI 1018 Mild/Low Carbon Steel
It is used in bending, crimping and swaging processes.
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.
It is widely used for fixtures, mounting plates and spacers.
It is suitably used in applications that do not need high strength of alloy steels and high carbon.
It 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.
It is used to prevent cracking in severe bends.
