UNS G98400

AISI 9840 steel, 540°C (1000°F) temper, 25 mm (1 in.) round
Categories: Metal; Ferrous Metal; Alloy Steel; AISI 9000 Series steel; Low Alloy Steel; Carbon Steel; Medium Carbon steel

Material Notes: Quenched, 540°C temper, 525°C nitride for 40 hours with 20-30% ammonia dissociation, hardness of 88 HR15N case hardness at 0.635-0.762 mm nitrided case depth

Key Words: UNS G98400, AMS 6342 C, ASTM A274, ASTM A322, ASTM A519, SAE J778, DIN 1.6511, UNI 38 NiCrMo 4, B.S. 816 M 40

Physical Properties Metric English Comments
Density 7.87 g/cc 0.284 lb/in³ field average for steels

Mechanical Properties Metric English Comments
Hardness, Brinell 361 361
Hardness, Knoop 390 390 Converted from Brinell hardness.
Hardness, Rockwell B 100 100 Converted from Brinell hardness.
Hardness, Rockwell C 35 35 core hardness. Quenched, 540°C temper, 525°C nitride for 40 hours with 20-30% ammonia dissociation
Hardness, Vickers 382 382 Converted from Brinell hardness.
Tensile Strength, Ultimate 1240 MPa 180000 psi
Tensile Strength, Yield 1105 MPa 160300 psi
Elongation at Break 15.0 % 15.0 % in 50 mm
Modulus of Elasticity 200 GPa 29000 ksi Estimated
Bulk Modulus 140 GPa 20300 ksi Typical for steel.
Poissons Ratio 0.290 0.290 Calculated
Machinability 70 % 70 % Estimated
Shear Modulus 80.0 GPa 11600 ksi Typical for steel

Electrical Properties Metric English Comments
Electrical Resistivity 0.0000174 ohm-cm 0.0000174 ohm-cm Estimated

Thermal Properties Metric English Comments
CTE, linear 11.5 µm/m-°C
@Temperature 20.0 °C 6.39 µin/in-°F
@Temperature 68.0 °F
12.2 µm/m-°C
@Temperature 250 °C 6.78 µin/in-°F
@Temperature 482 °F Estimated
13.9 µm/m-°C
@Temperature 500 °C 7.72 µin/in-°F
@Temperature 932 °F
14.7 µm/m-°C
@Temperature 1000 °C 8.17 µin/in-°F
@Temperature 1830 °F
Specific Heat Capacity 0.472 J/g-°C 0.113 BTU/lb-°F Estimated
Thermal Conductivity 51.9 W/m-K 360 BTU-in/hr-ft²-°F Typical steel

Component Elements Properties Metric English Comments
Carbon, C 0.380 - 0.430 % 0.380 - 0.430 %
Chromium, Cr 0.700 - 0.900 % 0.700 - 0.900 %
Iron, Fe 95.945 - 97.02 % 95.945 - 97.02 % As remainder
Manganese, Mn 0.700 - 0.900 % 0.700 - 0.900 %
Molybdenum, Mo 0.200 - 0.300 % 0.200 - 0.300 %
Nickel, Ni 0.850 - 1.15 % 0.850 - 1.15 %
Phosphorous, P <= 0.0350 % <= 0.0350 %
Silicon, Si 0.150 - 0.300 % 0.150 - 0.300 %
Sulfur, S <= 0.0400 % <= 0.0400 %

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M984AA / 8711