Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Incoloy 800H Mechanical Properties
Incoloy 800H (UNS N08810) and 800HT (UNS N08811) ship in the solution-annealed condition with the high-temperature anneal at 1149 deg C (2100 deg F) minimum required to deliver ASTM grain size 5 or coarser. Room-temperature specification floors per ASTM B407 (seamless pipe and tube), ASTM B408 (rod and bar) and ASTM B409 (plate, sheet and strip) are 65 ksi (450 MPa) ultimate tensile, 25 ksi (170 MPa) 0.2 percent proof stress, 30 percent elongation in 4D and Brinell hardness 120 to 184 HB. These are the cert floors that appear on the EN 10204 type 3.1 mill test report on every TorqBolt shipment. Elevated-temperature tensile and yield drop in line with the published Special Metals technical bulletin curves down to approximately 200 MPa (29 ksi) UTS at 815 deg C and 100 MPa (15 ksi) UTS at 982 deg C, with the ASME Section II Part D allowable design stresses tabulated below for use in pressure-vessel and piping calculations.
Room Temperature Mechanical Properties (Solution Annealed)
| Property | Incoloy 800H (N08810) | Incoloy 800HT (N08811) | Test method | Test condition |
|---|---|---|---|---|
| Ultimate tensile strength (Rm) | >= 450 MPa (65 ksi) | >= 450 MPa (65 ksi) | ASTM E8 / ISO 6892-1 | Room temperature, longitudinal, solution annealed |
| 0.2 percent proof stress (Rp0.2) | >= 170 MPa (25 ksi) | >= 170 MPa (25 ksi) | ASTM E8 / ISO 6892-1 | Room temperature, 0.2 percent offset |
| Elongation A5 (in 4D) | >= 30 percent | >= 30 percent | ASTM E8 gauge length 4D | Room temperature, longitudinal |
| Reduction of area | typically 50 to 60 percent | typically 50 to 60 percent | ASTM E8 | Room temperature |
| Brinell hardness (HB) | 120 to 184 HB | 120 to 184 HB | ASTM E10 (3000 kgf, 10 mm ball) | Maximum per ASTM B408 / B409 |
| Rockwell B equivalent | typically 65 to 90 HRB | typically 65 to 90 HRB | ASTM E18 | Indicative; B408 references Brinell |
| Charpy V-notch impact (RT) | typically > 130 J (96 ft-lbf) | typically > 130 J (96 ft-lbf) | ASTM E23 / ISO 148-1 | Not a B-series spec floor; reported on call-out |
| Modulus of elasticity (E) | 196 GPa (28.5 x 10^6 psi) | 196 GPa (28.5 x 10^6 psi) | ASTM E111 | Room temperature, longitudinal |
| Shear modulus (G) | 76 GPa (11.0 x 10^6 psi) | 76 GPa (11.0 x 10^6 psi) | ASTM E143 | Room temperature |
| ASTM grain size | 5 or coarser (mandatory) | 5 or coarser (mandatory) | ASTM E112 | After solution anneal at 1149 deg C minimum |
Elevated Temperature Tensile + Yield (Special Metals Bulletin Reference)
| Temperature (deg C) | Temperature (deg F) | Tensile strength (MPa / ksi) | 0.2 percent yield (MPa / ksi) | Elongation (percent) |
|---|---|---|---|---|
| 21 (RT) | 70 (RT) | 520 / 75 (typical) | 205 / 30 (typical) | 44 (typical) |
| 205 | 400 | 465 / 67 | 165 / 24 | 43 |
| 425 | 800 | 440 / 64 | 150 / 22 | 43 |
| 540 | 1000 | 420 / 61 | 145 / 21 | 44 |
| 650 | 1200 | 380 / 55 | 140 / 20 | 49 |
| 760 | 1400 | 290 / 42 | 135 / 19.5 | 62 |
| 815 | 1500 | 210 / 30 | 130 / 19 | 72 |
| 870 | 1600 | 165 / 24 | 105 / 15 | 80 |
| 925 | 1700 | 125 / 18 | 83 / 12 | 86 |
| 982 | 1800 | 97 / 14 | 65 / 9.5 | 96 |
Typical values from the Special Metals INCOLOY alloys 800H/800HT technical bulletin Table 4. Confirm against the heat-specific mill test certificate for design use.
ASME Section II Part D Allowable Design Stresses (Section VIII Division 1)
| Temperature (deg F) | Temperature (deg C) | Allowable stress S (ksi) | Allowable stress S (MPa) | Strength basis |
|---|---|---|---|---|
| 100 | 38 | 18.7 | 129 | Tensile-controlled |
| 200 | 93 | 18.4 | 127 | Tensile-controlled |
| 400 | 205 | 17.6 | 121 | Tensile-controlled |
| 600 | 316 | 17.0 | 117 | Tensile-controlled |
| 800 | 427 | 16.4 | 113 | Tensile-controlled |
| 1000 | 538 | 15.5 | 107 | Yield-controlled |
| 1100 | 593 | 15.0 | 103 | Yield-controlled |
| 1200 | 649 | 12.0 | 83 | Creep-rupture-controlled |
| 1300 | 704 | 7.7 | 53 | Creep-rupture-controlled |
| 1400 | 760 | 4.7 | 32 | Creep-rupture-controlled |
| 1500 | 815 | 2.5 | 17 | Creep-rupture-controlled (ASME Section VIII maximum) |
Indicative ASME Section II Part D Table 1A values for SB-407 / SB-408 / SB-409 / SB-564 plate, pipe, tube, bar and forgings. Verify against the current edition of the Code for design.
Test Methods + Cert Practice
Tensile + yield + elongation are reported on every TorqBolt heat to ASTM E8 with the 4D gauge length specified by ASTM B408 paragraph 9. Brinell hardness is reported to ASTM E10 with the 3000 kgf load and 10 mm tungsten carbide ball. Grain size is reported to ASTM E112 by the comparison method against the standard plate or by the planimetric Heyn method on a polished and etched cross-section. High-temperature tensile and yield are run to ASTM E21 when called for on the order, with the test temperature held to plus or minus 3 deg C and the strain rate to plus or minus 25 percent of the nominal value. Charpy impact testing is not a B-series specification floor but is reported on call-out for low-temperature transient service.
Strength Comparison to Adjacent Grades at 815 deg C
| Alloy | UNS | UTS at 815 deg C (MPa) | Service ceiling (deg C) | Step rationale |
|---|---|---|---|---|
| Incoloy 800 | N08800 | ~180 | 650 | Below 800H creep envelope; step up for sustained > 650 deg C |
| Incoloy 800H | N08810 | ~210 | 815 | ASME Section VIII pressure-vessel standard |
| Incoloy 800HT | N08811 | ~220 | 982 | Step up when sustained service is above 815 deg C |
| 310H stainless | S31009 | ~140 | 900 (oxidation only) | Lower creep strength; not preferred above 700 deg C structural |
| Inconel 625 | N06625 | ~365 | 650 (sustained) | Higher strength but Laves-phase embrittlement above 650 deg C |
Engineering Implications
- The room-temperature 30 percent elongation floor sets the cold-formability envelope for plate and sheet rolled into pressure-vessel sections.
- The 196 GPa modulus is approximately 4 percent lower than carbon steel, which lifts the deflection in long unsupported spans of heat exchanger tube banks.
- The yield-to-tensile ratio of approximately 0.40 at room temperature is comfortably below the 0.85 piping code ceiling, so 800H is not strain-controlled in piping fatigue analysis.
- Above 650 deg C the allowable design stress is creep-rupture controlled, not yield-controlled, see the dedicated creep-rupture strength page for the time-dependent stress tables.
- For sustained service above 815 deg C, step up to 800HT (UNS N08811) for the gamma-prime-enhanced creep strength.
- Compare against the chemistry envelope and the high-temperature strength tables for the full design dataset.
Frequently Asked Questions
What is the room-temperature yield strength of Incoloy 800H?
170 MPa (25 ksi) 0.2 percent proof stress minimum per ASTM B408 paragraph 9. Typical mill heats run 200 to 240 MPa.
What grain size is required for 800H certification?
ASTM grain size 5 or coarser, measured to ASTM E112 after the solution anneal at 1149 deg C (2100 deg F) minimum followed by rapid cool. A fine-grain heat that meets every chemistry envelope still fails the 800H qualification at grain size 6 or finer.
How does the strength compare to 304H or 316H stainless?
At room temperature the tensile floors are similar (450 MPa for 800H, 515 MPa for 304H, 515 MPa for 316H). Above 650 deg C the comparison reverses: 800H holds approximately 380 MPa UTS at 650 deg C, while 304H drops below 350 MPa and 316H drops below 360 MPa. Above 760 deg C the gap widens further in favour of 800H.
What is the maximum ASME Section VIII design temperature?
815 deg C (1500 deg F) for Incoloy 800H per Section II Part D Table 1A. Incoloy 800HT extends the qualified ceiling to 899 deg C (1650 deg F) under Code Case 2196.
Are hardness values restricted by NACE MR0175?
800H is not on the NACE MR0175 Table A.27 base list for sour service in the as-supplied condition. For sour service at temperature, specify the alternative materials in NACE MR0175 Annex A.
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