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Our Tools' Material AISI 1045,AISI5140

Our Tools' Material AISI 1045,AISI5140
Update Time:2015-07-08

AISI 1045 Medium Carbon Steel


AISI 1045 steel is a medium tensile steel supplied in the 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 size around 60 mm 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

Carbon, C0.420 - 0.50 %
Iron, Fe98.51 - 98.98 %
Manganese, Mn0.60 - 0.90 %
Phosphorous, P≤ 0.040 %
Sulfur, S≤ 0.050 %

Physical Properties

Physical PropertiesMetricImperial
Density7.87 g/cc0.284 lb/in3

Mechanical Properties

Mechanical PropertiesMetricImperial
Hardness, Brinell163163
Hardness, Knoop (Converted from Brinell hardness)184184
Hardness, Rockwell B (Converted from Brinell hardness)8484
Hardness, Vickers (Converted from Brinell hardness)170170
Tensile Strength, Ultimate565 MPa81900 psi
Tensile Strength, Yield310 MPa45000 psi
Elongation at Break (in 50 mm)16.0 %16.0 %
Reduction of Area40.0 %40.0 %
Modulus of Elasticity (Typical for steel)200 GPa29000 ksi
Bulk Modulus (Typical for steel)140 GPa20300 ksi
Poissons Ratio (Typical For Steel)0.2900.290
Shear Modulus (Typical for steel)80 GPa11600 ksi


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


Certain facts about welding of AISI 1045 steel are:

  • AISI 1045 steel is readily welded when correct procedure is followed.
  • Welding AISI 1045 steel in through-hardened, tempered and flame or induction hardened condition 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, ashes etc and
    • Stress relieved at 550°C - 660°C (1022°F - 1220°F).

Heat Treatment

AISI 1045 is subjected to the following processes:

  • Forging
  • Annealing
  • Normalizing
  • Stress relieving
  • Hardening
  • Tempering


  • Heat to 850°C - 1250°C (1562°F - 2282°F)
  • Hold until the temperature is uniform
  • Cool in furnace


  • Heat to 800°C - 850°C (1472°F - 1562°F)
  • Hold until the temperature is uniform
  • Cool in furnace.


  • 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


  • 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


  • 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:

BoltsRatchetsLight gears
StudsCrankshaftsGuide rods
Connecting rodsTorsion bars

Hydraulic clamps



AISI 5140 Alloy Steel


Alloy steels comprise a wide range of steels whose compositions are more than the limitations of C, Mo, Cr, Va, Mn, Ni, Si, and B which have been fixed for carbon steels. These steels are more responsive to mechanical and heat treatments than carbon steels.

The following datasheet will provide details about AISI 5140 alloy steel.

Chemical Composition

The following table shows the chemical composition of AISI 5140 alloy steel.

ElementContent (%)
Iron, Fe97.395-98.07
Manganese, Mn0.700-0.900
Chromium, Cr0.700-0.900
Carbon, C0.380-0.430
Silicon, Si0.150-0.300
Sulfur, S≤ 0.0400
Phosphorous, P≤ 0.0350

Physical Properties

The physical properties of AISI 5140 alloy steel are outlined in the following table.

Density7.85 g/cm30.284 lb/in³

Mechanical Properties

The mechanical properties of annealed AISI 5140 alloy steel are highlighted in the table below.

Tensile strength570 MPa82700 psi
Yield strength295 MPa42800 psi
Elastic modulus190-210 GPa27557-30458 ksi
Bulk modulus (typical for steel)140 GPa20300 ksi
Shear modulus (typical for steel)80 GPa11600 ksi
Poisson’s ratio0.27-0.300.27-0.30
Izod Impact41.0 J30.2 ft.lb
Hardness, Brinell167167
Hardness, Knoop (converted from Brinell hardness)188188
Hardness, Rockwell B (converted from Brinell hardness)8585
Hardness, Vickers (converted from Brinell hardness)175175
Machinability (annealed and cold drawn, based on 100 machinability for AISI 1212 steel)6565

Thermal Properties

The thermal properties of AISI 5140 alloy steel are provided in the table below.

Thermal conductivity44.6 W/mK310 BTU in/hr.ft².°F
Thermal expansion co-efficient (@20-200°C/68-392°F)12.6 µm/m°C7 µin/in°F

Other Designations

Equivalent materials to AISI 5140 alloy steel are as follows.

AFNOR 42 C 2AFNOR 42 C 4DIN 1.7035UNI 40 Cr 4UNI 41 Cr 4 KBJIS SCr 4 H
B.S. 2 S 117B.S. 530 A 40B.S. 530 H 40B.S. 530 M 40ASTM A322ASTM A331

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