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ASTM A372 Grade J Class 55 vs. ASTM A372 Grade J Class 65

Both ASTM A372 grade J class 55 and ASTM A372 grade J class 65 are variants of the same material. They share alloy composition and many physical properties, but develop different mechanical properties as a result of different processing.

For each property being compared, the top bar is ASTM A372 grade J class 55 and the bottom bar is ASTM A372 grade J class 65.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 200
250
Elastic (Young's, Tensile) Modulus, GPa 190
190
Elongation at Break, % 22
21
Fatigue Strength, MPa 310
360
Poisson's Ratio 0.29
0.29
Shear Modulus, GPa 73
73
Shear Strength, MPa 410
510
Tensile Strength: Ultimate (UTS), MPa 650
810
Tensile Strength: Yield (Proof), MPa 430
510

Thermal Properties

Latent Heat of Fusion, J/g 250
250
Maximum Temperature: Mechanical, °C 420
420
Melting Completion (Liquidus), °C 1460
1460
Melting Onset (Solidus), °C 1420
1420
Specific Heat Capacity, J/kg-K 470
470
Thermal Conductivity, W/m-K 44
44
Thermal Expansion, µm/m-K 13
13

Electrical Properties

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

Otherwise Unclassified Properties

Base Metal Price, % relative 2.4
2.4
Density, g/cm3 7.8
7.8
Embodied Carbon, kg CO2/kg material 1.5
1.5
Embodied Energy, MJ/kg 20
20
Embodied Water, L/kg 51
51

Common Calculations

Resilience: Ultimate (Unit Rupture Work), MJ/m3 130
150
Resilience: Unit (Modulus of Resilience), kJ/m3 500
700
Stiffness to Weight: Axial, points 13
13
Stiffness to Weight: Bending, points 24
24
Strength to Weight: Axial, points 23
29
Strength to Weight: Bending, points 21
25
Thermal Diffusivity, mm2/s 12
12
Thermal Shock Resistance, points 19
24

Alloy Composition

Carbon (C), % 0.35 to 0.5
0.35 to 0.5
Chromium (Cr), % 0.8 to 1.2
0.8 to 1.2
Iron (Fe), % 96.7 to 97.8
96.7 to 97.8
Manganese (Mn), % 0.75 to 1.1
0.75 to 1.1
Molybdenum (Mo), % 0.15 to 0.25
0.15 to 0.25
Phosphorus (P), % 0 to 0.015
0 to 0.015
Silicon (Si), % 0.15 to 0.35
0.15 to 0.35
Sulfur (S), % 0 to 0.010
0 to 0.010