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SAE-AISI 4340 Steel vs. SAE-AISI 4340M Steel

Both SAE-AISI 4340 steel and SAE-AISI 4340M steel are iron alloys. They have a very high 98% of their average alloy composition in common. There are 31 material properties with values for both materials. Properties with values for just one material (4, in this case) are not shown.

For each property being compared, the top bar is SAE-AISI 4340 steel and the bottom bar is SAE-AISI 4340M steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 210 to 360
710
Elastic (Young's, Tensile) Modulus, GPa 190
190
Elongation at Break, % 12 to 22
6.0
Fatigue Strength, MPa 330 to 740
690
Poisson's Ratio 0.29
0.29
Shear Modulus, GPa 73
72
Shear Strength, MPa 430 to 770
1360
Tensile Strength: Ultimate (UTS), MPa 690 to 1280
2340
Tensile Strength: Yield (Proof), MPa 470 to 1150
1240

Thermal Properties

Latent Heat of Fusion, J/g 250
280
Maximum Temperature: Mechanical, °C 430
430
Melting Completion (Liquidus), °C 1460
1440
Melting Onset (Solidus), °C 1420
1400
Specific Heat Capacity, J/kg-K 470
480
Thermal Conductivity, W/m-K 44
38
Thermal Expansion, µm/m-K 13
13

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 7.5
7.8
Electrical Conductivity: Equal Weight (Specific), % IACS 8.6
9.1

Otherwise Unclassified Properties

Base Metal Price, % relative 3.5
3.9
Density, g/cm3 7.8
7.8
Embodied Carbon, kg CO2/kg material 1.7
1.9
Embodied Energy, MJ/kg 22
26
Embodied Water, L/kg 53
55

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 79 to 170
120
Resilience: Unit (Modulus of Resilience), kJ/m3 590 to 3490
4120
Stiffness to Weight: Axial, points 13
13
Stiffness to Weight: Bending, points 24
25
Strength to Weight: Axial, points 24 to 45
84
Strength to Weight: Bending, points 22 to 33
51
Thermal Diffusivity, mm2/s 12
10
Thermal Shock Resistance, points 20 to 38
70

Alloy Composition

Carbon (C), % 0.38 to 0.43
0.38 to 0.43
Chromium (Cr), % 0.7 to 0.9
0.7 to 1.0
Iron (Fe), % 95.1 to 96.3
93.3 to 94.8
Manganese (Mn), % 0.6 to 0.8
0.65 to 0.9
Molybdenum (Mo), % 0.2 to 0.3
0.35 to 0.45
Nickel (Ni), % 1.7 to 2.0
1.7 to 2.0
Phosphorus (P), % 0 to 0.035
0 to 0.012
Silicon (Si), % 0.15 to 0.35
1.5 to 1.8
Sulfur (S), % 0 to 0.040
0 to 0.012
Vanadium (V), % 0
0.050 to 0.1