AISI 4140 Steel, normalized at 870°C (1600°F), reheated to 845°C (1550°F), oil quenched, 205°C (400°F) temper, 25 mm (1 in.) round
Categories: Metal; Ferrous Metal; Alloy Steel; AISI 4000 Series Steel; Low Alloy Steel; Carbon Steel; Medium Carbon Steel
Material Notes: Sample normalized at 870°C, reheated to 845°C (1550°F), oil quenched, and tempered at 205°C. As quenched hardness after oil quenching: Surface - 55 HRC, 1/2 radius - 55 HRC; Center - 50 HRC
Key Words: ASTM A322, ASTM A331, ASTM A505, ASTM A519, ASTM A646, B.S. 708 A 42 (UK), B.S. 708 M 40 (UK), B.S. 709 M 40 (UK), JIS SCM 4 H, JIS SCM 4, JIS SCM440, SS14 2244 (Sweden), MIL SPEC MIL-S-16974, SAE J404, SAE J412, SAE J770, DIN 1.7225, UNS G41400, AMS 6381, AMS 6382, AMS 6390, AMS 6395, IS 1570 40Cr1Mo28, IS 4367 40Cr1Mo28, IS 5517 40Cr1Mo28
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Physical PropertiesMetricEnglishComments
Density 7.85 g/cc0.284 lb/in³
 
Mechanical PropertiesMetricEnglishComments
Hardness, Brinell 578578
Hardness, Knoop 616616Converted from Brinell
Hardness, Rockwell C 5555Converted from Brinell
Hardness, Vickers 614614Converted from Brinell
Tensile Strength, Ultimate 1965 MPa285000 psi
Tensile Strength, Yield 1735 MPa251600 psi
Elongation at Break 11 %11 %
Reduction of Area 42 %42 %
Modulus of Elasticity 205 GPa29700 ksiTypical for steel
Bulk Modulus 160 GPa23200 ksiTypical for steel
Poissons Ratio 0.290.29Calculated
Machinability 65 %65 %Based on AISI 1212 as 100% machinability.
Shear Modulus 80.0 GPa11600 ksiTypical for steel
Izod Impact 15.0 J11.1 ft-lb
 
Electrical PropertiesMetricEnglishComments
Electrical Resistivity  0.0000220 ohm-cm
@Temperature 20.0 °C		0.0000220 ohm-cm
@Temperature 68.0 °F		specimen hardened and tempered
 0.0000263 ohm-cm
@Temperature 100 °C		0.0000263 ohm-cm
@Temperature 212 °F		specimen hardened and tempered
 0.0000326 ohm-cm
@Temperature 200 °C		0.0000326 ohm-cm
@Temperature 392 °F		specimen hardened and tempered
 0.0000475 ohm-cm
@Temperature 400 °C		0.0000475 ohm-cm
@Temperature 752 °F		specimen hardened and tempered
 0.0000646 ohm-cm
@Temperature 600 °C		0.0000646 ohm-cm
@Temperature 1110 °F		specimen hardened and tempered
 
Thermal PropertiesMetricEnglishComments
CTE, linear  12.2 µm/m-°C
@Temperature 0.000 - 100 °C		6.78 µin/in-°F
@Temperature 32.0 - 212 °F
 13.7 µm/m-°C
@Temperature 20.0 - 400 °C		7.61 µin/in-°F
@Temperature 68.0 - 752 °F
 14.6 µm/m-°C
@Temperature 20.0 - 600 °C		8.11 µin/in-°F
@Temperature 68.0 - 1110 °F
Specific Heat Capacity  0.473 J/g-°C
@Temperature 150 - 200 °C		0.113 BTU/lb-°F
@Temperature 302 - 392 °F
 0.519 J/g-°C
@Temperature 350 - 400 °C		0.124 BTU/lb-°F
@Temperature 662 - 752 °F
 0.561 J/g-°C
@Temperature 550 - 600 °C		0.134 BTU/lb-°F
@Temperature 1020 - 1110 °F
Thermal Conductivity 42.6 W/m-K296 BTU-in/hr-ft²-°F
 
Component Elements PropertiesMetricEnglishComments
Carbon, C 0.38 - 0.43 %0.38 - 0.43 %
Chromium, Cr 0.80 - 1.1 %0.80 - 1.1 %
Iron, Fe 96.785 - 97.77 %96.785 - 97.77 %As remainder
Manganese, Mn 0.75 - 1.0 %0.75 - 1.0 %
Molybdenum, Mo 0.15 - 0.25 %0.15 - 0.25 %
Phosphorus, P <= 0.035 %<= 0.035 %
Silicon, Si 0.15 - 0.30 %0.15 - 0.30 %
Sulfur, S <= 0.040 %<= 0.040 %

References for this datasheet.

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