Reviewed by Lexie CornerUpdated on Nov 22 2024
AISI 1045 steel is medium-tensile steel supplied in a black hot-rolled or normalized condition. Its tensile strength is 570 - 700 MPa, and Brinell hardness ranges between 170 and 210.
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AISI 1045 steel is known for its good weldability, machinability, and high strength and impact properties in both normalized and hot-rolled conditions. These properties, combined with its exceptional performance at high temperatures, make AISI 1045 a versatile material, widely used in industrial applications where strength, wear resistance, and reliability are critical.
| Gears |
Pins |
Rams |
| Shafts |
Rolls |
Sockets |
| Axles |
Spindles |
Worms |
| Bolts |
Ratchets |
Light gears |
| Studs |
Crankshafts |
Guide rods |
| Connecting rods |
Torsion bars |
Hydraulic clamps |
AISI 1045 steel has limited through-hardening capability, with sections up to approximately 60 mm suitable for tempering and through-hardening. However, it can be effectively flame or induction-hardened in the normalized or hot-rolled condition to achieve surface hardnesses ranging from Rc 54 to Rc 60, depending on factors such as section size, setup, and quenching medium.
Due to its lack of alloying elements, AISI 1045 steel does not respond to the nitriding process.
Standards and Composition
Chemical Composition
| Element |
Content |
| Carbon, C |
0.420 - 0.50 % |
| Iron, Fe |
98.51 - 98.98 % |
| Manganese, Mn |
0.60 - 0.90 % |
| Phosphorous, P |
≤ 0.040 % |
| Sulfur, S |
≤ 0.050 % |
Alternatives to AISI 1045, such as M1030 and 4140, require additional pre-treatment processes, particularly for strengthening the carbon core, making AISI 1045 a cost-effective and adaptable choice in its category
Physical Properties
| Physical Properties |
Metric |
Imperial |
| Density |
7.87 g/cc |
0.284 lb/in3 |
Mechanical Properties
| Mechanical Properties |
Metric |
Imperial |
| Hardness, Brinell |
163 |
163 |
| Hardness, Knoop (Converted from Brinell hardness) |
184 |
184 |
| Hardness, Rockwell B (Converted from Brinell hardness) |
84 |
84 |
| Hardness, Vickers (Converted from Brinell hardness) |
170 |
170 |
| Tensile Strength, Ultimate |
565 MPa |
81900 psi |
| Tensile Strength, Yield |
310 MPa |
45000 psi |
| Elongation at Break (in 50 mm) |
16.0 % |
16.0 % |
| Reduction of Area |
40.0 % |
40.0 % |
| Modulus of Elasticity (Typical for steel) |
200 GPa |
29000 ksi |
| Bulk Modulus (Typical for steel) |
140 GPa |
20300 ksi |
| Poissons Ratio (Typical For Steel) |
0.290 |
0.290 |
| Shear Modulus (Typical for steel) |
80 GPa |
11600 ksi |
Heat Treatment
AISI 1045 is subjected to various heat treatment processes to optimize its mechanical properties:
- Forging - Heat to 850 °C - 1250°C (1562 °F – 2282 °F). Hold until the temperature is uniform. Cool in a furnace.
- Annealing - Heat to 800 °C - 850°C (1472 °F – 1562 °F). Hold until the temperature is uniform. Cool in a furnace.
- Normalizing - Heat to 870 °C – 920 °C (1598 °F – 1688 °F). Hold until the temperature is uniform. Soak for 10 - 15 minutes. Cool in still air.
- Stress-Relieving - Heat to 550 °C – 660 °C (1022 °F – 1220 °F). Hold until the temperature is uniform. Soak for 1 hour per 25mm of section. Cool in still air.
- Hardening - Heat to 820 °C – 850 °C (1508 °F – 1562 °F). Hold until the temperature is uniform. Soak for 10 - 15 minutes per 25mm of section. Quench in water or brine.
- Tempering - Re-heat to 400 °C – 650 °C (752 °F – 1202 °F) as required. Hold until the temperature is uniform. Soak for 1 hour per 25mm of section. Cool in still air.
Machining and Welding
AISI 1045 steel has good machinability in a normalized or hot-rolled condition. Based on manufacturer recommendations, operations such as tapping, milling, broaching, drilling, turning, and sawing can be performed using appropriate feeds, tools, and speeds.
Welding is possible with correct procedures but is not recommended for through-hardened, tempered, or flame-/induction-hardened conditions. Low hydrogen electrodes are preferred for welding.
Steps for welding include:
- Preheating to 200–300 °C (392–572 °F)
- Maintaining the same temperature during welding
- Cooling slowly using sand or ashes
- Stress-relieving at 550–660 °C (1022–1220 °F)