Sep 13 2012
Topics Covered
IntroductionChemical CompositionPhysical PropertiesMechanical PropertiesOther DesignationsFabrication and Heat Treatment Machinability Forming Welding Heat Treatment Cold Working Annealing Tempering HardeningApplications
Introduction
Carbon is the major alloying element present in carbon steels. They also contain 0.4% of silicon and 1.2% of manganese. The AISI 1140 carbon steel is a free cutting steel. It has high strength, and is combined with sulfur in order to increase its machining characteristics.
The following datasheet gives an overview of AISI 1140 carbon steel.
Chemical Composition
The following table shows the chemical composition of AISI 1140 carbon steel.
| Element |
Content (%) |
| Iron, Fe |
98.39 - 98.93 |
| Manganese, Mn |
0.700 - 1.00 |
| Carbon, C |
0.370 - 0.440 % |
| Sulfur, S |
≤ 0.130 |
| Phosphorous, P |
≤ 0.0400 |
Physical Properties
The physical properties of AISI 1140 carbon steel are tabulated below.
| Properties |
Metric |
Imperial |
| Density |
7.7-8.03 g/cm3 |
0.278-0.290 lb/in3 |
| Melting point |
1455°C |
2650°F |
Mechanical Properties
The mechanical properties of AISI 1140 carbon steel are outlined in the following table.
| Properties |
Metric |
Imperial |
| Elastic modulus |
190-210 GPa |
27557-30458 ksi |
| Poisson's ratio |
0.27-0.30 |
0.27-0.30 |
Other Designations
Other designations that are equivalent to AISI 1140 carbon steel include:
- ASTM A29
- ASTM A510
- ASTM A576
- SAE J1397
- SAE J403
- SAE J412
Fabrication and Heat Treatment
Machinability
The machinability rate of AISI 1140 carbon steel is 70.
Forming
AISI 1140 carbon steel can be formed using conventional techniques.
Welding
It is advised that AISI 1140 carbon steel should not be welded because the presence of sulfur can result in the formation of gas porosity, thus reducing the properties of the steel.
Heat Treatment
AISI 1140 carbon steel can be normalized at 899°C (1650°F). It is then heat treated at 815 to 899°C (1550 to 1650°F) and quenched in oil or water followed by tempering.
Cold Working
AISI 1140 carbon steel should not be subjected to cold working process such as swaging or cold heading as it can be crumbled or splitted. However, other conventional processes do not result in impact stress.
Annealing
Annealing of AISI 1140 carbon steel can be done at 872°C (1600°F). It is then slowly cooled in the furnace. Stress relief annealing process can also be performed at 538°C (1000°F).
Tempering
AISI 1140 carbon steel is tempered at 315 to 705°C (600 to 1300°F).
Hardening
AISI 1140 carbon steel is hardened by cold work or by heat treatment.
Applications
AISI 1140 carbon steel is mainly used in screw stock or high speed and free machining operations.