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SAE-AISI 4340 Steel vs. AISI 420 Stainless Steel

Both SAE-AISI 4340 steel and AISI 420 stainless steel are iron alloys. They have 88% of their average alloy composition in common. There are 31 material properties with values for both materials. Properties with values for just one material (3, in this case) are not shown.

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

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 210 to 360
190
Elastic (Young's, Tensile) Modulus, GPa 190
190
Elongation at Break, % 12 to 22
8.0 to 15
Fatigue Strength, MPa 330 to 740
220 to 670
Poisson's Ratio 0.29
0.28
Shear Modulus, GPa 73
76
Shear Strength, MPa 430 to 770
420 to 1010
Tensile Strength: Ultimate (UTS), MPa 690 to 1280
690 to 1720
Tensile Strength: Yield (Proof), MPa 470 to 1150
380 to 1310

Thermal Properties

Latent Heat of Fusion, J/g 250
280
Maximum Temperature: Mechanical, °C 430
620
Melting Completion (Liquidus), °C 1460
1510
Melting Onset (Solidus), °C 1420
1450
Specific Heat Capacity, J/kg-K 470
480
Thermal Conductivity, W/m-K 44
27
Thermal Expansion, µm/m-K 13
10

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 7.5
3.0
Electrical Conductivity: Equal Weight (Specific), % IACS 8.6
3.5

Otherwise Unclassified Properties

Base Metal Price, % relative 3.5
7.5
Density, g/cm3 7.8
7.7
Embodied Carbon, kg CO2/kg material 1.7
2.0
Embodied Energy, MJ/kg 22
28
Embodied Water, L/kg 53
100

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 79 to 170
88 to 130
Resilience: Unit (Modulus of Resilience), kJ/m3 590 to 3490
380 to 4410
Stiffness to Weight: Axial, points 13
14
Stiffness to Weight: Bending, points 24
25
Strength to Weight: Axial, points 24 to 45
25 to 62
Strength to Weight: Bending, points 22 to 33
22 to 41
Thermal Diffusivity, mm2/s 12
7.3
Thermal Shock Resistance, points 20 to 38
25 to 62

Alloy Composition

Carbon (C), % 0.38 to 0.43
0.15 to 0.4
Chromium (Cr), % 0.7 to 0.9
12 to 14
Iron (Fe), % 95.1 to 96.3
82.3 to 87.9
Manganese (Mn), % 0.6 to 0.8
0 to 1.0
Molybdenum (Mo), % 0.2 to 0.3
0 to 0.5
Nickel (Ni), % 1.7 to 2.0
0 to 0.75
Phosphorus (P), % 0 to 0.035
0 to 0.040
Silicon (Si), % 0.15 to 0.35
0 to 1.0
Sulfur (S), % 0 to 0.040
0 to 0.030

Comparable Variants