Alloy 800HT / Incoloy 800HT
Alloy 800HT is a further controlled version of Alloy 800H with restricted carbon, aluminium and titanium contents and specified heat treatment to improve elevated-temperature creep and stress-rupture performance.
Alloy 800HT / Incoloy 800HT Information
Alloy 800HT is a further controlled version of Alloy 800H with restricted carbon, aluminium and titanium contents and specified heat treatment to improve elevated-temperature creep and stress-rupture performance.
Metallic winding and compatible ring components where service conditions are suitable.
| UNS Number | N08811 |
|---|---|
| Correct Trade Family | INCOLOY alloy 800HT |
| Material Type | Controlled C/Al/Ti Ni-Fe-Cr high-temperature alloy |
| Common / Applicable Specification | ASTM B409 / applicable 800HT specification |
| Typical Gasket Use | Metallic winding and compatible ring components where service conditions are suitable. |
Alloy 800HT / Incoloy 800HT Chemical Composition
Reference composition limits are shown below. Exact requirements should be confirmed against the applicable product specification and certified material documentation.
| Element / Constituent | Symbol | Composition / Information |
|---|---|---|
| Nickel | Ni | 30.0–35.0 |
| Chromium | Cr | 19.0–23.0 |
| Iron | Fe | Balance |
| Carbon | C | 0.06–0.10 |
| Aluminium | Al | 0.25–0.60 |
| Titanium | Ti | 0.25–0.60 |
| Al + Ti | Al+Ti | 0.85–1.20 |
| Manganese | Mn | 1.50 max. |
| Silicon | Si | 1.00 max. |
Alloy 800HT / Incoloy 800HT Mechanical Properties
Reference room-temperature properties are shown for a commonly supplied condition. Exact requirements depend on product form, size, heat treatment and governing specification.
| Property | Reference Value | Unit / Basis |
|---|---|---|
| Tensile Strength | ≈450–520 min. | MPa |
| 0.2% Offset Yield Strength | ≈170–205 min. | MPa |
| Elongation | ≈30 min. | % |
Values shown are engineering reference data, not universal design allowables. Final procurement and design must use the governing specification, exact product form/condition and certified material test documentation.
Alloy 800HT / Incoloy 800HT Physical & Service Information
Reference physical properties and service considerations relevant to material selection for Spiral Wound Gaskets.
| Density | Approx. 7.94 g/cm³ |
|---|---|
| Structure | Austenitic Ni-Fe-Cr alloy |
| High-Temperature Behaviour | Enhanced creep and stress-rupture performance for elevated-temperature service. |
| Heat Treatment | Specified solution treatment and grain-size control are important to the grade designation. |
| Service Selection | Do not substitute standard Alloy 800 where 800HT creep-strength qualification is required. |
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