Editorial Feature

AISI 1045 Medium Carbon Steel

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AISI 1045 steel is a medium tensile steel supplied in a black hot-rolled or normalized condition. It has a tensile strength of 570 - 700 MPa and Brinell hardness ranging between 170 and 210.

AISI 1045 steel is characterized by good weldability, good machinability, and high strength and impact properties in either the normalized or hot-rolled condition.

AISI 1045 steel has a low through-hardening capability with only sections of around 60 mm in size being recommended as suitable for tempering and through-hardening. However, it can be efficiently flame- or induction-hardened in the normalized or hot rolled condition to obtain surface hardnesses in the range of Rc 54 - Rc 60 based on factors such as section size, type of set up, quenching medium used etc.

AISI 1045 steel lacks suitable alloying elements and hence does not respond to the nitriding process.

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 %

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


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AISI 1045 steel has good machinability in a normalized or hot-rolled condition. Based on the recommendations given by the machine manufacturers, operations like tapping, milling, broaching, drilling, turning and sawing can be carried out on AISI 1045 steel using suitable feeds, tool type, and speeds.


AISI 1045 steel is readily welded when the correct procedure is followed, but welding AISI 1045 steel in through-hardened, tempered and flame- or induction-hardened conditions is not recommended. Low hydrogen electrodes are preferred for welding AISI 1045 steel.

The workpiece is:

  • Pre-heated at 200°C–300°C (392°F - 572°F);
  • maintained at the same temperature during welding;
  • cooled slowly using sand or ashes; and
  • stress relieved at 550°C - 660°C (1022°F - 1220°F).

Heat Treatment

AISI 1045 is subjected to forging, annealing, normalizing, stress-relieving, hardening and tempering processes – each of which is explained in more detail below:

  • 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.


AISI 1045 is widely used for all industrial applications requiring more wear-resistance and strength. Typical applications of AISI 1045 are as follows:

Gears Pins Rams
Shafts Rolls Sockets
Axles Spindles Worms
Bolts Ratchets Light gears
Studs Crankshafts Guide rods
Connecting rods Torsion bars Hydraulic clamps

This article was updated on 7th August, 2019.


  1. hissan shah hissan shah India says:

    I want to mfg A105 flanges which rod should i use?

  2. Tim Hogue Tim Hogue United States says:

    Can this steel be hot-dip galvanized?  I will be using it as a structural pin in an outdoor industrial environment.

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