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ASTM A387 Grade 9 Steel vs. ASTM A372 Grade K Steel

Both ASTM A387 grade 9 steel and ASTM A372 grade K steel are iron alloys. They have a moderately high 91% of their average alloy composition in common.

For each property being compared, the top bar is ASTM A387 grade 9 steel and the bottom bar is ASTM A372 grade K steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 150 to 180
230
Elastic (Young's, Tensile) Modulus, GPa 190
190
Elongation at Break, % 20 to 21
23
Fatigue Strength, MPa 160 to 240
440
Poisson's Ratio 0.28
0.29
Shear Modulus, GPa 75
73
Shear Strength, MPa 310 to 380
490
Tensile Strength: Ultimate (UTS), MPa 500 to 600
780
Tensile Strength: Yield (Proof), MPa 230 to 350
620

Thermal Properties

Latent Heat of Fusion, J/g 270
250
Maximum Temperature: Mechanical, °C 600
440
Melting Completion (Liquidus), °C 1460
1460
Melting Onset (Solidus), °C 1410
1420
Specific Heat Capacity, J/kg-K 470
470
Thermal Conductivity, W/m-K 26
48
Thermal Expansion, µm/m-K 13
13

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 9.0
7.8
Electrical Conductivity: Equal Weight (Specific), % IACS 10
8.9

Otherwise Unclassified Properties

Base Metal Price, % relative 6.5
4.4
Density, g/cm3 7.8
7.9
Embodied Carbon, kg CO2/kg material 2.1
1.8
Embodied Energy, MJ/kg 28
24
Embodied Water, L/kg 87
57

Common Calculations

PREN (Pitting Resistance) 12
2.7
Resilience: Ultimate (Unit Rupture Work), MJ/m3 83 to 110
160
Resilience: Unit (Modulus of Resilience), kJ/m3 140 to 310
1010
Stiffness to Weight: Axial, points 14
13
Stiffness to Weight: Bending, points 25
24
Strength to Weight: Axial, points 18 to 21
27
Strength to Weight: Bending, points 18 to 20
24
Thermal Diffusivity, mm2/s 6.9
13
Thermal Shock Resistance, points 14 to 17
23

Alloy Composition

Carbon (C), % 0 to 0.15
0 to 0.18
Chromium (Cr), % 8.0 to 10
1.0 to 1.8
Iron (Fe), % 87.1 to 90.8
93.4 to 96.6
Manganese (Mn), % 0.3 to 0.6
0.1 to 0.4
Molybdenum (Mo), % 0.9 to 1.1
0.2 to 0.6
Nickel (Ni), % 0
2.0 to 3.3
Phosphorus (P), % 0 to 0.025
0 to 0.015
Silicon (Si), % 0 to 1.0
0.15 to 0.35
Sulfur (S), % 0 to 0.025
0 to 0.010
Vanadium (V), % 0 to 0.040
0