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SAE-AISI 8740 Steel vs. AISI 309S Stainless Steel

Both SAE-AISI 8740 steel and AISI 309S stainless steel are iron alloys. They have 64% 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 8740 steel and the bottom bar is AISI 309S stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 170 to 200
190
Elastic (Young's, Tensile) Modulus, GPa 190
200
Elongation at Break, % 11 to 23
42
Fatigue Strength, MPa 270 to 350
210
Poisson's Ratio 0.29
0.27
Shear Modulus, GPa 73
78
Shear Strength, MPa 370 to 400
400
Tensile Strength: Ultimate (UTS), MPa 580 to 670
580
Tensile Strength: Yield (Proof), MPa 380 to 570
230

Thermal Properties

Latent Heat of Fusion, J/g 250
290
Maximum Temperature: Mechanical, °C 410
1080
Melting Completion (Liquidus), °C 1460
1420
Melting Onset (Solidus), °C 1420
1370
Specific Heat Capacity, J/kg-K 470
480
Thermal Conductivity, W/m-K 39
15
Thermal Expansion, µm/m-K 13
16

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 7.3
2.2
Electrical Conductivity: Equal Weight (Specific), % IACS 8.4
2.5

Otherwise Unclassified Properties

Base Metal Price, % relative 2.6
19
Density, g/cm3 7.8
7.8
Embodied Carbon, kg CO2/kg material 1.5
3.6
Embodied Energy, MJ/kg 20
51
Embodied Water, L/kg 50
170

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 71 to 120
190
Resilience: Unit (Modulus of Resilience), kJ/m3 390 to 850
140
Stiffness to Weight: Axial, points 13
14
Stiffness to Weight: Bending, points 24
25
Strength to Weight: Axial, points 20 to 24
21
Strength to Weight: Bending, points 20 to 22
20
Thermal Diffusivity, mm2/s 10
4.0
Thermal Shock Resistance, points 17 to 20
13

Alloy Composition

Carbon (C), % 0.38 to 0.43
0 to 0.080
Chromium (Cr), % 0.4 to 0.6
22 to 24
Iron (Fe), % 96.5 to 97.7
58.1 to 66
Manganese (Mn), % 0.75 to 1.0
0 to 2.0
Molybdenum (Mo), % 0.2 to 0.3
0
Nickel (Ni), % 0.4 to 0.7
12 to 15
Phosphorus (P), % 0 to 0.035
0 to 0.045
Silicon (Si), % 0.15 to 0.35
0 to 0.75
Sulfur (S), % 0 to 0.040
0 to 0.030