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AISI 304H Stainless Steel vs. AISI 321H Stainless Steel

Both AISI 304H stainless steel and AISI 321H stainless steel are iron alloys. Both are furnished in the annealed condition. They have a very high 98% of their average alloy composition in common.

For each property being compared, the top bar is AISI 304H stainless steel and the bottom bar is AISI 321H stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 180
190
Elastic (Young's, Tensile) Modulus, GPa 200
200
Elongation at Break, % 40
40
Fatigue Strength, MPa 200
200
Poisson's Ratio 0.28
0.28
Reduction in Area, % 51
51
Rockwell B Hardness 79
82
Shear Modulus, GPa 77
77
Shear Strength, MPa 400
400
Tensile Strength: Ultimate (UTS), MPa 580
580
Tensile Strength: Yield (Proof), MPa 230
230

Thermal Properties

Latent Heat of Fusion, J/g 290
290
Maximum Temperature: Corrosion, °C 420
480
Maximum Temperature: Mechanical, °C 960
940
Melting Completion (Liquidus), °C 1430
1430
Melting Onset (Solidus), °C 1380
1380
Specific Heat Capacity, J/kg-K 480
480
Thermal Conductivity, W/m-K 17
15
Thermal Expansion, µm/m-K 16
17

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 2.4
2.4
Electrical Conductivity: Equal Weight (Specific), % IACS 2.8
2.7

Otherwise Unclassified Properties

Base Metal Price, % relative 15
16
Density, g/cm3 7.8
7.8
Embodied Carbon, kg CO2/kg material 3.0
3.2
Embodied Energy, MJ/kg 43
46
Embodied Water, L/kg 150
140

Common Calculations

PREN (Pitting Resistance) 19
18
Resilience: Ultimate (Unit Rupture Work), MJ/m3 190
190
Resilience: Unit (Modulus of Resilience), kJ/m3 130
140
Stiffness to Weight: Axial, points 14
14
Stiffness to Weight: Bending, points 25
25
Strength to Weight: Axial, points 21
21
Strength to Weight: Bending, points 20
20
Thermal Diffusivity, mm2/s 4.5
4.0
Thermal Shock Resistance, points 13
12

Alloy Composition

Carbon (C), % 0.040 to 0.1
0.040 to 0.1
Chromium (Cr), % 18 to 20
17 to 19
Iron (Fe), % 66.6 to 74
65.4 to 74
Manganese (Mn), % 0 to 2.0
0 to 2.0
Nickel (Ni), % 8.0 to 10.5
9.0 to 12
Phosphorus (P), % 0 to 0.045
0 to 0.045
Silicon (Si), % 0 to 0.75
0 to 0.75
Sulfur (S), % 0 to 0.030
0 to 0.030
Titanium (Ti), % 0
0 to 0.7