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SAE-AISI 4320 Steel vs. ASTM A229 Spring Steel

Both SAE-AISI 4320 steel and ASTM A229 spring steel are iron alloys. They have a very high 97% of their average alloy composition in common.

For each property being compared, the top bar is SAE-AISI 4320 steel and the bottom bar is ASTM A229 spring steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 160 to 240
490 to 550
Elastic (Young's, Tensile) Modulus, GPa 190
190
Elongation at Break, % 21 to 29
14
Fatigue Strength, MPa 320
710 to 790
Poisson's Ratio 0.29
0.29
Shear Modulus, GPa 73
72
Shear Strength, MPa 370 to 500
1020 to 1140
Tensile Strength: Ultimate (UTS), MPa 570 to 790
1690 to 1890
Tensile Strength: Yield (Proof), MPa 430 to 460
1100 to 1230

Thermal Properties

Latent Heat of Fusion, J/g 250
250
Maximum Temperature: Mechanical, °C 420
400
Melting Completion (Liquidus), °C 1460
1450
Melting Onset (Solidus), °C 1420
1410
Specific Heat Capacity, J/kg-K 470
470
Thermal Conductivity, W/m-K 46
50
Thermal Expansion, µm/m-K 11
12

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 7.4
7.2
Electrical Conductivity: Equal Weight (Specific), % IACS 8.5
8.3

Otherwise Unclassified Properties

Base Metal Price, % relative 3.4
1.8
Density, g/cm3 7.9
7.8
Embodied Carbon, kg CO2/kg material 1.7
1.4
Embodied Energy, MJ/kg 22
19
Embodied Water, L/kg 52
46

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 140 to 150
200 to 230
Resilience: Unit (Modulus of Resilience), kJ/m3 480 to 560
3260 to 4080
Stiffness to Weight: Axial, points 13
13
Stiffness to Weight: Bending, points 24
24
Strength to Weight: Axial, points 20 to 28
60 to 67
Strength to Weight: Bending, points 19 to 24
40 to 43
Thermal Diffusivity, mm2/s 13
14
Thermal Shock Resistance, points 19 to 27
54 to 60

Alloy Composition

Carbon (C), % 0.17 to 0.22
0.55 to 0.85
Chromium (Cr), % 0.4 to 0.6
0
Iron (Fe), % 95.8 to 97
97.5 to 99
Manganese (Mn), % 0.45 to 0.65
0.3 to 1.2
Molybdenum (Mo), % 0.2 to 0.3
0
Nickel (Ni), % 1.7 to 2.0
0
Phosphorus (P), % 0 to 0.035
0 to 0.040
Silicon (Si), % 0.15 to 0.35
0.15 to 0.35
Sulfur (S), % 0 to 0.040
0 to 0.050

Comparable Variants