Jun 17 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Forming
Welding
Heat Treatment
Forging
Hot Working
Cold Working
Annealing
Applications
Introduction
There are many different categories of steel, and carbon steels are one such category that contains 0.12 to 2% carbon in them. The steel gains hardness and strength with heat treatment when the carbon percentage content increases; however its ductility is reduced.
AISI 1018 carbon steel is a free machining grade that is the most commonly available grade around the world. Although its mechanical properties are not very unique, it still can be easily formed, machined, welded and fabricated.
The following sections will discuss in detail about AISI 1018 carbon steel.
Chemical Composition
The chemical composition of AISI 1018 carbon steel is outlined in the following table.
|
Element |
Content (%) |
|
Manganese, Mn |
0.60-0.90 |
|
Carbon, C |
0.15-0.20 |
|
Sulfur, S |
0.05 (max) |
|
Phosphorous, P |
0.04 (max) |
|
Iron, Fe |
Balance |
Physical Properties
The physical properties of AISI 1018 carbon steel are tabulated below.
|
Properties |
Metric |
Imperial |
|
Density |
7.87 g/cm3 |
0.284 lb/in3 |
Mechanical Properties
The following table shows mechanical properties of cold drawn AISI 1018 carbon steel.
|
Properties |
Metric |
Imperial |
|
Tensile strength |
440 MPa |
63800 psi |
|
Yield strength |
370 MPa |
53700 psi |
|
Modulus of elasticity |
205 GPa |
29700 ksi |
|
Shear modulus (typical for steel) |
80 GPa |
11600 ksi |
|
Poisson’s ratio |
0.29 |
0.29 |
|
Elongation at break (in 50 mm) |
15% |
15% |
|
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 |
|
Machinability (based on AISI 1212 steel. as 100 machinability) |
70 |
70 |
Thermal Properties
The thermal properties of AISI 1018 carbon steel are given in the following table.
|
Properties |
Metric |
Imperial |
|
Thermal conductivity |
51.9 W/mK |
360 BTU in/hr.ft2.°F |
Other Designations
Other designations that are equivalent to AISI 1018 carbon steel include the following.
|
AMS 5069 |
ASTM A29 |
ASTM A512 |
ASTM A611 (D-1) |
ASTM A635 |
|
AMS 5069A |
ASTM A510 |
ASTM A794 |
ASTM A519 |
ASTM A544 |
|
ASTM A108 |
ASTM A513 |
ASTM A830 |
ASTM A545 |
ASTM A548 |
|
ASTM A549 |
ASTM A659 |
SAE J412 |
SAE J1397 |
MIL S-11310 (CS 1018) |
|
ASTM A576 |
SAE J403 |
SAE J414 |
MIL J-1397 |
MIL J-403 |
MIL J-412
|
|
|
|
|
Fabrication and Heat Treatment
Machinability
AISI 1018 carbon steel is rated at 62% of AISI 1112 carbon steel. Machining provides this alloy with a fine finish, with continuous and hard chips. It is possible to machine this alloy in all conditions.
Forming
It is easy to form AISI 1018 carbon steel in the annealed condition.
Welding
AISI 1018 carbon steel can be welded using most of the conventional methods such as gas, oxyacetylene, resistance, and submerged melt welding.
Heat Treatment
AISI 1018 carbon steel can be case hardened to Rc 42, but only in thin sections. In case of thicker sections of over 4 in., Rc 28-30 can be obtained.
Forging
Forging of AISI 1018 carbon steel can take place in the range of 996-1260°C (1825-2300°F).
Hot Working
AISI 1018 carbon steel can be easily hot worked.
Cold Working
Cold working AISI 1018 carbon steel will affect the hardness and mechanical properties. Intermediate annealing has to be performed to overcome the alloy’s tendency to work harden.
Annealing
Complete annealing of this alloy can be achieved by soaking at 899°C (1650°F) followed by furnace cooling. Process annealing can be done at 649°C (1200°F).
Applications
AISI 1018 carbon steel is commonly used in high volume screw machine parts applications. The other applications of this alloy are as follows:
-
Shafts
-
Spindles
-
Pins
-
Rods
-
Sprocket assemblies.