UNS N08811 (Alloy 800HT) Stainless Steel
N08811 stainless steel is a superaustenitic (highly alloyed) stainless steel formulated for primary forming into wrought products. Cited properties are appropriate for the annealed condition. N08811 is the UNS number for this material. Alloy 800HT is the common industry name.
This material is well established: the Further Reading section below cites a number of published standards, and that list is not necessarily exhaustive.
It has a very low tensile strength among wrought superaustenitic stainless steels. In addition, it has a moderately low base cost and a fairly low ductility.
The graph bars on the material properties cards below compare N08811 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
Elastic (Young's, Tensile) Modulus
200 GPa 29 x 106 psi
Elongation at Break
33 %
Fatigue Strength
150 MPa 22 x 103 psi
Poisson's Ratio
0.28
Shear Modulus
77 GPa 11 x 106 psi
Shear Strength
340 MPa 49 x 103 psi
Tensile Strength: Ultimate (UTS)
510 MPa 74 x 103 psi
Tensile Strength: Yield (Proof)
190 MPa 28 x 103 psi
Thermal Properties
Curie Temperature
-120 °C -180 °F
Latent Heat of Fusion
300 J/g
Maximum Temperature: Corrosion
490 °C 920 °F
Maximum Temperature: Mechanical
1100 °C 2010 °F
Melting Completion (Liquidus)
1390 °C 2530 °F
Melting Onset (Solidus)
1360 °C 2470 °F
Specific Heat Capacity
480 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
12 W/m-K 6.6 BTU/h-ft-°F
Thermal Expansion
14 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
1.7 % IACS
Electrical Conductivity: Equal Weight (Specific)
2.0 % IACS
Otherwise Unclassified Properties
Base Metal Price
30 % relative
Density
8.0 g/cm3 500 lb/ft3
Embodied Carbon
5.3 kg CO2/kg material
Embodied Energy
76 MJ/kg 33 x 103 BTU/lb
Embodied Water
200 L/kg 24 gal/lb
Common Calculations
PREN (Pitting Resistance)
21
Resilience: Ultimate (Unit Rupture Work)
130 MJ/m3
Resilience: Unit (Modulus of Resilience)
94 kJ/m3
Stiffness to Weight: Axial
14 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
18 points
Strength to Weight: Bending
18 points
Thermal Diffusivity
3.0 mm2/s
Thermal Shock Resistance
13 points
Alloy Composition
Among wrought stainless steels, the composition of N08811 stainless steel is notable for including aluminum (Al) and titanium (Ti). Aluminum is used to improve oxidation resistance. It can also enhance the effects of heat treatment. Titanium is used to broadly improve mechanical properties.
| Fe | 39.5 to 50.6 | |
| Ni | 30 to 35 | |
| Cr | 19 to 23 | |
| Mn | 0 to 1.5 | |
| Si | 0 to 1.0 | |
| Al | 0.15 to 0.6 | |
| Ti | 0.15 to 0.6 | |
| Cu | 0 to 0.75 | |
| C | 0.060 to 0.1 | |
| P | 0 to 0.040 | |
| S | 0 to 0.015 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM B408: Standard Specification for Nickel-Iron-Chromium Alloy Rod and Bar
ASTM B515: Standard Specification for Welded UNS N08120, UNS N08800, UNS N08810, and UNS N08811 Alloy Tubes
ASTM B409: Standard Specification for Nickel-Iron-Chromium Alloy Plate, Sheet, and Strip
ASTM B407: Standard Specification for Nickel-Iron-Chromium Alloy Seamless Pipe and Tube
ASTM B564: Standard Specification for Nickel Alloy Forgings
Machining of Stainless Steels and Super Alloys: Traditional and Nontraditional Techniques, Helmi A. Youssef, 2016
Nickel Alloys, Ulrich Heubner (editor), 1998
ASTM A240: Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications
Welding Metallurgy of Stainless Steels, Erich Folkhard et al., 2012
ASTM A959: Standard Guide for Specifying Harmonized Standard Grade Compositions for Wrought Stainless Steels