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SAE-AISI 4340M Steel vs. AISI 420 Stainless Steel

Both SAE-AISI 4340M steel and AISI 420 stainless steel are iron alloys. They have 88% of their average alloy composition in common. There are 32 material properties with values for both materials. Properties with values for just one material (5, in this case) are not shown.

For each property being compared, the top bar is SAE-AISI 4340M steel and the bottom bar is AISI 420 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 710
190
Elastic (Young's, Tensile) Modulus, GPa 190
190
Elongation at Break, % 6.0
8.0 to 15
Fatigue Strength, MPa 690
220 to 670
Poisson's Ratio 0.29
0.28
Shear Modulus, GPa 72
76
Shear Strength, MPa 1360
420 to 1010
Tensile Strength: Ultimate (UTS), MPa 2340
690 to 1720
Tensile Strength: Yield (Proof), MPa 1240
380 to 1310

Thermal Properties

Latent Heat of Fusion, J/g 280
280
Maximum Temperature: Mechanical, °C 430
620
Melting Completion (Liquidus), °C 1440
1510
Melting Onset (Solidus), °C 1400
1450
Specific Heat Capacity, J/kg-K 480
480
Thermal Conductivity, W/m-K 38
27
Thermal Expansion, µm/m-K 13
10

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 7.8
3.0
Electrical Conductivity: Equal Weight (Specific), % IACS 9.1
3.5

Otherwise Unclassified Properties

Base Metal Price, % relative 3.9
7.5
Density, g/cm3 7.8
7.7
Embodied Carbon, kg CO2/kg material 1.9
2.0
Embodied Energy, MJ/kg 26
28
Embodied Water, L/kg 55
100

Common Calculations

PREN (Pitting Resistance) 2.2
14
Resilience: Ultimate (Unit Rupture Work), MJ/m3 120
88 to 130
Resilience: Unit (Modulus of Resilience), kJ/m3 4120
380 to 4410
Stiffness to Weight: Axial, points 13
14
Stiffness to Weight: Bending, points 25
25
Strength to Weight: Axial, points 84
25 to 62
Strength to Weight: Bending, points 51
22 to 41
Thermal Diffusivity, mm2/s 10
7.3
Thermal Shock Resistance, points 70
25 to 62

Alloy Composition

Carbon (C), % 0.38 to 0.43
0.15 to 0.4
Chromium (Cr), % 0.7 to 1.0
12 to 14
Iron (Fe), % 93.3 to 94.8
82.3 to 87.9
Manganese (Mn), % 0.65 to 0.9
0 to 1.0
Molybdenum (Mo), % 0.35 to 0.45
0 to 0.5
Nickel (Ni), % 1.7 to 2.0
0 to 0.75
Phosphorus (P), % 0 to 0.012
0 to 0.040
Silicon (Si), % 1.5 to 1.8
0 to 1.0
Sulfur (S), % 0 to 0.012
0 to 0.030
Vanadium (V), % 0.050 to 0.1
0