Incoloy Alloy 800/800H/800HT
INCOLOY alloy 800HT has a restricted chemistry, within the limits of alloy 800H, and requires a heat treatment of 2100°F (1149°C) minimum. The carbon is 0.06 to 0.10% (alloy 800H is 0.05 to 0.10%), the Al + Ti is 0.85 to 1.20% (alloy 800H is 0.30 to 1.20% Al + Ti).
The maximum allowable stresses for INCOLOY alloy 800HT (UNS N08811) is contained in ASME Code Case 1987 – latest revision. The alloy meets all the requirements for UNS N08811 and N08810 (alloy 800H) and can be certified to either or both UNS numbers. It is important to note that INCOLOY alloy 800HT (UNS N08811) has higher maximum allowable design stresses than UNS N08810. Therefore, other materials produced to UNS N08810 (alloy 800H) cannot be certified as UNS N08811 unless they meet the additional requirements for this designation. INCOLOY alloy 800HT is the result of years of monitoring and maintaining the ultimate properties in this series of alloys by The Special Metals Corporation group of companies, the inventor of all the INCOLOY 800 series alloys.
INCOLOY alloys 800H and 800HT have significantly higher creep and rupture strength than INCOLOY alloy 800. The three alloys have nearly identical chemical composition limits.
| Weight % | Ni | Cr | Fe | C | Al | Ti | Al+Ti |
| Alloy 800 | 30-35 | 19-23 | 39.5 min | 0.10 max | 0.15-0.60 | 0.15-0.60 | 0.30-1.20 |
| Alloy 800H | 30-35 | 19-23 | 39.5 | 0.05-0.10 | 0.15-0.60 | 0.15-0.60 | 0.30-1.20 |
| Alloy 800HT | 30-35 | 19-23 | 39.5 | 0.06-0.10 | 0.25-0.60 | 0.25-0.60 | 0.85-1.20 |
| ASTM Grain Size – Alloy 800 is not specified, Alloy 800H is 5 or coarser, Alloy 800HT is 5 or coarser. | |||||||
Mechanical Properties
| Material | Temp. | Hardness | Tensile Strength | Yield Strength (0.2% Offset) | |||
| °F | °C | BHN | ksi | MPa | KSI | MPa | |
| Alloy 800H and Alloy 800HT | 80 | 27 | 126 | 77.8 | 536 | 21.7 | 150 |
| Alloy 800H and Alloy 800HT | 800 | 425 | 67.5 | 465 | 18.8 | 130 | |
| Alloy 800H and Alloy 800HT | 1000 | 540 | 90 | 62.7 | 432 | 13.0 | 90 |
| Alloy 800H and Alloy 800HT | 1200 | 650 | 84 | 54.8 | 378 | 13.5 | 93 |
| Alloy 800H and Alloy 800HT | 1300 | 705 | 82 | 47.7 | 329 | 15.8 | 109 |
| Alloy 800H and Alloy 800HT | 1400 | 760 | 74 | 34.2 | 236 | 13.1 | 90 |
| Alloy 800HT is a Trademark of Special Metals Corporation | |||||||
Available Products and Specifications
INCOLOY alloys 800H and 800HT are designated as UNS N08810 and UNS N08811 and Werkstoff Numbers 1.4876, 1.4958 and 1.4959. INCOLOY alloys 800H and 800HT are available in all standard mill forms including rod, bar, plate, sheet, strip, shapes, and tubular products.
Rod, Bar, Wire, Forgings, and Forging Stock – ASTM B408 & ASME SB408 (Rod & Bar), ASTM B564 & ASME SB564 (Forgings), ASME Code Case 1325 (All Product Forms), ASME Code Case 1949 (Forgings), ISO 9723 (Rod & Bar), ISO 9724 (Wire), ISO 9725 (Forgings), BS 3076NA15 (Rod & Bar), BS 3075NA15 (Wire), SEW 470 (All Products), VdTÜV 412 & 434 (All Products), DIN 17460 (Rod, Bar, & Forgings), EN 10095 (Rod & Bar)
Plate, Sheet, and Strip – ASTM A240/A480 & ASME SA240/SA480 (Plate, Sheet, and Strip), ASTM B409/B906 & ASME SB409/SB906 (Plate, Sheet, and Strip), ASME Code Case 1325 (All Product Forms), ASME Code Case 2339 (INCOLOY alloy 800H Plate), BS 3072NA15 (Plate & Sheet), BS 3073NA15 (Strip), SEW 470 (All Products), VdTÜV 412 & 434 (All Products), DIN 17460 (Plate, Sheet, & Strip), EN 10028-7 & EN 10095 (Plate, Sheet, & Strip)
Pipe and Tubes – ASTM B163 & ASME SB163 (Seamless Condenser & Heat Exchanger Tubes), ASTM B407/B829 & ASME SB407/SB829 (Seamless Pipe & Tubes), ASTM B514/B775 & ASME SB514/SB775 (Welded Pipe), ASTM B515/B751 & ASME SB515/SB751(Welded Tubes), ASME Code Case 1325 (All Product Forms) and 1983 (Seamless Pipe & Tubes), BS 3074NA15 (Seamless Pipe & Tubes), SEW 470 (All Products), VdTÜV 412 & 434 (All Products), ISO 6207 (Seamless Tubes), DIN 17459 (Seamless Pipe & Tubing)
Other Product Forms – ASTM B366 & ASME SB366 (Fittings), ASME Code Cases N-201 & N-254 (All Products for Nuclear Construction), ISO 4955A (General)
