Sep 26 2012
Topics Covered
IntroductionChemical CompositionPhysical PropertiesMechanical PropertiesFabrication and Heat Treatment Tempering Annealing Cold Working Welding Forging Forming Machinability Heat Treatment Hot Working HardeningApplications
Introduction
Alloy steels contain a wide range of steels comprising compositions that exceed the limitations of Si, Va, Cr, Ni, Mo, Mn, B and C which have been allocated for carbon steels. Alloy steels can be used in unique melting and deoxidization processes for specific kind of applications.
Alloy steels comprise elements such as chromium, cobalt, nickel etc, that are not found in carbon steels. In comparison with carbon steels, alloy steels are a lot more responsive to mechanical and heat treatments.
The following datasheet provides an overview of AISI 4330 alloy steel.
Chemical Composition
The chemical composition of AISI 4330 alloy steel is outlined in the following table.
| Element |
Content (%) |
| Iron, Fe |
95.3-98.1 |
| Nickel, Ni |
1.0-1.50 |
| Manganese, Mn |
≤ 1.0 |
| Silicon, Si |
≤ 0.80 |
| Chromium, Cr |
0.40-0.60 |
| Molybdenum, Mo |
0.30-0.50 |
| Carbon, C |
0.20-0.30 |
Physical Properties
The following table shows the physical properties of AISI 4330 alloy steel.
| Properties |
Metric |
Imperial |
| Melting point |
1427°C |
2600°F |
Mechanical Properties
The mechanical properties of AISI 4330 alloy steel are displayed in the following table.
| Properties |
Metric |
Imperial |
| Tensile strength |
≥ 860 MPa |
≥ 125000 psi |
| Yield strength |
≥ 690 MPa |
≥ 100000 psi |
| Elongation at break (In 50 mm) |
≥ 15.0 % |
≥ 15.0 % |
| Hardness, Brinell |
285 |
285 |
Fabrication and Heat Treatment
Tempering
AISI 4330 alloy steel is tempered based on the desired state level. This alloy steel is tempered at 454 to 635°C (850 to 1175°F) for the lower strength 125 to 200 ksi level. AISI 4330 alloy steel is tempered at 218 to 260°C (425 to 500°F) for the 260 to 280 ksi level. Tempering is not recommended for strength levels in the 220 to 260 ksi range as this will lead to degradation of impact strength.
Annealing
AISI 4330 alloy steel can be completely annealed at 816 to 899°C (1500 to 1650°F). The alloy is then cooled slowly in the furnace and finally cooled in air.
Cold Working
AISI 4330 alloy steel has good cold working characteristics. Conventional methods are used for cold working this alloy steel.
Welding
Conventional methods are used for welding AISI 4330 alloy steel. AISI 4330 alloy steel is preheated and post heated based on the welding procedure used for this alloy steel type, and the alloy can be joined by a brazing process.
Forging
AISI 4330 alloy steel is forged in the temperature range of 1204 to 982°C (2200 to 1800°F).
Forming
AISI 4330 alloy steel has good formability characteristics and the bend radii for this alloy should not be sharper that a 3t bend.
Machinability
AISI 4330 alloy steel has good machinability features in the annealed, tempered and normalized conditions. This alloy steel is difficult to be machined in the hardened condition.
Heat Treatment
AISI 4330 alloy steel is heated to 829°C (1525°F) and then quenched in oil. AISI 4330 alloy steel can also be heat treated to strength levels of 200 ksi or greater than 200 ksi, by first being normalized at 899°C (1650°F) before the heat treatment and then quenched to gain strength.
Hot Working
AISI 4330 alloy steel is generally not hot worked as it already has good cold forming features.
Hardening
AISI 4330 alloy steel can be hardened by being tempered and heat treated.
Applications
AISI 4330 alloy steel are used in aircraft landing gears, shafts or axels for power transmission and gears.