Hangbo Alloy Group
Shanghai · Est. 2012
N06693 technical guide: nominal chemical composition, mechanical and physical properties, corrosion resistance, welding, product forms and ASTM standards...
Inconel 693 (UNS N06693) is a nickel-chromium-aluminium alloy. High Cr + Al for sulfidation & chlorine resistance. Developed for waste-to-energy / biomass boilers. This guide covers its nominal chemical composition, typical mechanical and physical properties, corrosion behaviour, welding, common applications, available product forms and the ASTM standards that apply — everything a specifier needs to evaluate Inconel 693 for a project.
Inconel 693 belongs to the nickel-chromium-aluminium alloy class of materials. It is high cr + al for sulfidation & chlorine resistance. It is developed for waste-to-energy / biomass boilers. It is good high-temperature oxidation resistance.
Nominal (wt%) composition of Inconel 693 (UNS N06693):
| Element | Composition (wt%) |
|---|---|
| Nickel (Ni) | ≥ 58.0 |
| Chromium (Cr) | 26.0 – 30.0 |
| Iron (Fe) | Balance |
| Aluminium (Al) | 2.5 – 4.0 |
| Niobium (Nb) | 1.4 – 2.4 |
| Titanium (Ti) | ≤ 0.6 |
| Carbon (C) | ≤ 0.15 |
| Manganese (Mn) | ≤ 1.0 |
| Silicon (Si) | ≤ 1.0 |
| Sulphur (S) | ≤ 0.015 |
| Copper (Cu) | ≤ 0.5 |
| Cobalt (Co) | ≤ 1.0 |
Typical physical properties:
| Property | Value |
|---|---|
| Density | 7.95 g/cm³ |
| Melting Range | 1300 – 1370 °C |
| Thermal Expansion (20–1000 °C) | 14.4 µm/m·K |
| Thermal Conductivity (100 °C) | 11.7 W/m·K |
| Modulus of Elasticity | 200 GPa |
Typical room-temperature mechanical properties (annealed / specified condition unless noted):
| Property | Typical Value |
|---|---|
| Tensile Strength (Rm) | 760 MPa (110 ksi) |
| Yield Strength, 0.2% (Rp0.2) | 425 MPa (62 ksi) |
| Elongation in 50 mm | 40% |
| Hardness (Rockwell B) | 80 – 95 HRB |
| Property | Value |
|---|---|
| Service temperature | Up to 1050 °C |
| Sulfidation resistance | Excellent (high Cr + Al) |
693 was developed for waste-to-energy and biomass boilers. Its very high chromium plus 2.5–4 % aluminium gives exceptional resistance to high-temperature sulfidation, chlorine/salt corrosion and oxidation. Niobium improves strength and stabilises the microstructure in aggressive flue-gas environments.
Welded with matching ERNiCrCoMo-?? type fillers or overalloyed consumables; field repairs of sulfidation-damaged tubes use 693 as a weld overlay. Follow a qualified procedure for the overlay.
The grade is supplied to the following common specifications:
| Standard | Product Form / Scope |
|---|---|
| ASTM B619/B622 | Welded/Seamless pipe & tube |
| ASTM B626/B625 | Welded tube / plate-sheet |
| ASTM B366 | Fittings |
Standards & References. Specifications cited on this page; confirm current revisions with the issuing body.
General references: Nickel Institute · AMPP (corrosion) · SAE International · ASTM International
693 was specifically developed for waste-to-energy and biomass power boilers where flue gas contains chlorides, alkali salts and sulfur. Its high chromium and 2.5–4 % aluminium resist sulfidation, chlorine corrosion and oxidation better than standard austenitic alloys.
The 26–30 % chromium plus 2.5–4 % aluminium forms robust chromium-alumina scales that hold up in high-temperature sulfidising and chlorinating gases that destroy 300-series stainless and even many Ni-Cr alloys.
Yes. 693 weld wire is used to overlay and repair sulfidation-damaged boiler tubes and hangers in waste-to-energy plants, extending component life significantly.
Annealed: ≈ 760 MPa tensile, ≈ 425 MPa yield, 40 % elongation, 80–95 HRB. It is serviceable up to about 1050 °C.
Seamless and welded pipe/tube are covered by ASTM B622/B619 and B626, plate/sheet by B625, fittings by B366.
625 resists general pitting well but lacks the aluminium needed for severe high-temperature sulfidation. 693 is the dedicated grade for that sulfidising/chlorinating flue-gas regime.
As a dedicated nickel alloy manufacturer serving power generation, chemical processing, marine sectors, Hangbo Alloy Group supplies the grades discussed here across all standard product forms with full ASTM/ASME documentation and EN 10204 3.1 certification. Our material is specified for applications where corrosion resistance, high-temperature strength, and traceable quality are non-negotiable. See our production & testing facilities for more on how every heat is verified.