---
title: "Inconel 625 / 718"
description: "Inconel 625 and Inconel 718 are nickel-based superalloys (trademarks of Special Metals Corporation) used for industrial sonic horn bells and diaphragms in hot-side service above ~500 °C continuous temperature, where AISI 316 would lose mechanical strength."
canonical_url: "https://sylio.co/glossary/inconel-625-718"
last_updated: "2026-06-28T02:29:35.375Z"
---

**Inconel 625** and **Inconel 718** are nickel-based superalloys (trademarks of Special Metals Corporation) used for industrial [sonic horn](/glossary/sonic-horn) bells and [diaphragms](/glossary/diaphragm-horn) in hot-side service above ~500 °C continuous temperature, where [AISI 316](/glossary/aisi-316-316l-stainless) would lose mechanical strength.

## Properties

<table>
<thead>
  <tr>
    <th>
      Property
    </th>
    
    <th>
      Inconel 625
    </th>
    
    <th>
      Inconel 718
    </th>
  </tr>
</thead>

<tbody>
  <tr>
    <td>
      Composition
    </td>
    
    <td>
      Ni-Cr-Mo-Nb
    </td>
    
    <td>
      Ni-Cr-Fe with age-hardening
    </td>
  </tr>
  
  <tr>
    <td>
      Continuous service
    </td>
    
    <td>
      up to ~980 °C
    </td>
    
    <td>
      up to ~700 °C
    </td>
  </tr>
  
  <tr>
    <td>
      Strength
    </td>
    
    <td>
      High at moderate temp
    </td>
    
    <td>
      Highest at moderate-high temp
    </td>
  </tr>
  
  <tr>
    <td>
      Cost vs 316
    </td>
    
    <td>
      5–10×
    </td>
    
    <td>
      4–8×
    </td>
  </tr>
  
  <tr>
    <td>
      Best application
    </td>
    
    <td>
      Sustained high-temp duty
    </td>
    
    <td>
      Strength-critical components
    </td>
  </tr>
</tbody>
</table>

## Where Inconel is specified

- [Hot-side ESP](/glossary/hot-side-esp-cold-side-esp) penthouses (300–400 °C continuous)
- [SCR reactor](/glossary/selective-catalytic-reduction) horn installations (300–400 °C)
- [Recovery-boiler](/glossary/recovery-boiler) superheater area
- Cement [kiln-inlet](/glossary/kiln-inlet-riser-duct) horns
- Some [WtE](/glossary/waste-to-energy) high-chloride hot zones

## Related terms

- [AISI 316 / 316L stainless](/glossary/aisi-316-316l-stainless)
- [Hastelloy](/glossary/hastelloy)
- [Bell horn](/glossary/bell-horn)
- [Diaphragm horn](/glossary/diaphragm-horn)