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UNS N08028 (Alloy 28) Stainless Steel

N08028 stainless steel is a superaustenitic (highly alloyed) stainless steel formulated for primary forming into wrought products. Cited properties are appropriate for the annealed condition. N08028 is the UNS number for this material. Alloy 28 is the common industry name.

It has a moderately high base cost among wrought superaustenitic stainless steels. In addition, it has a moderately high ductility and a moderately high embodied energy.

The graph bars on the material properties cards below compare N08028 stainless steel to: wrought superaustenitic stainless steels (top), all iron alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Brinell Hardness

180

Elastic (Young's, Tensile) Modulus

200 GPa 30 x 106 psi

Elongation at Break

45 %

Fatigue Strength

220 MPa 32 x 103 psi

Poisson's Ratio

0.28

Rockwell B Hardness

80

Shear Modulus

80 GPa 12 x 106 psi

Shear Strength

400 MPa 57 x 103 psi

Tensile Strength: Ultimate (UTS)

570 MPa 82 x 103 psi

Tensile Strength: Yield (Proof)

240 MPa 35 x 103 psi

Thermal Properties

Latent Heat of Fusion

320 J/g

Maximum Temperature: Corrosion

460 °C 850 °F

Maximum Temperature: Mechanical

1100 °C 2010 °F

Melting Completion (Liquidus)

1420 °C 2580 °F

Melting Onset (Solidus)

1370 °C 2490 °F

Specific Heat Capacity

470 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

12 W/m-K 6.9 BTU/h-ft-°F

Thermal Expansion

16 µm/m-K

Otherwise Unclassified Properties

Base Metal Price

37 % relative

Density

8.1 g/cm3 500 lb/ft3

Embodied Carbon

6.4 kg CO2/kg material

Embodied Energy

89 MJ/kg 38 x 103 BTU/lb

Embodied Water

240 L/kg 28 gal/lb

Common Calculations

PREN (Pitting Resistance)

39

Resilience: Ultimate (Unit Rupture Work)

210 MJ/m3

Resilience: Unit (Modulus of Resilience)

140 kJ/m3

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

19 points

Strength to Weight: Bending

19 points

Thermal Diffusivity

3.2 mm2/s

Thermal Shock Resistance

12 points

Alloy Composition

Among wrought stainless steels, the composition of N08028 stainless steel is notable for containing comparatively high amounts of chromium (Cr) and manganese (Mn). Chromium is the defining alloying element of stainless steel. Higher chromium content imparts additional corrosion resistance. Manganese is used to improve ductility at elevated temperatures. It also permits a higher nitrogen content than would otherwise be possible.

Iron (Fe) 29 to 40.4
Nickel (Ni) 30 to 34
Chromium (Cr) 26 to 28
Molybdenum (Mo) 3.0 to 4.0
Manganese (Mn) 0 to 2.5
Copper (Cu) 0.6 to 1.4
Silicon (Si) 0 to 1.0
Carbon (C) 0 to 0.030
Phosphorus (P) 0 to 0.030
Sulfur (S) 0 to 0.030

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

ASTM B668: Standard Specification for UNS N08028 Seamless Pipe and Tube

ASTM B709: Standard Specification for Iron-Nickel-Chromium-Molybdenum Alloy (UNS N08028) Plate, Sheet, and Strip

Nickel Alloys, Ulrich Heubner (editor), 1998

Corrosion of Austenitic Stainless Steels: Mechanism, Mitigation and Monitoring, H. S. Khatak and B. Raj (editors), 2002

Austenitic Stainless Steels: Microstructure and Mechanical Properties, P. Marshall, 1984

ASM Specialty Handbook: Stainless Steels, J. R. Davis (editor), 1994

Advances in Stainless Steels, Baldev Raj et al. (editors), 2010

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015