When selecting nickel-based alloys for hydrochloric acid (HCl) service, corrosion resistance-not just strength-becomes the decisive factor. Two high-performance alloys often considered are Inconel® 718 (UNS N07718) and HAYNES® 282® (UNS N07208). While both are premium nickel alloys, their behavior in hydrochloric acid environments differs significantly.
This article provides a clear, data-driven comparison of Inconel 718 vs Haynes 282 in HCl, helping procurement teams avoid costly material misselection.
Why is hydrochloric acid a critical testing environment?
Hydrochloric acid is one of the most corrosive reducing acids and has the following effects on metallic materials: rapid dissolution of metals, severe pitting and crevice corrosion, and the inability of most alloys to form a stable protective oxide layer in a hydrochloric acid environment. Many high-strength nickel alloys, despite their excellent high-temperature performance, still fail in hydrochloric acid environments.
Is Inconel 718 resistant to hydrochloric acid corrosion?
Is Inconel 718 resistant to hydrochloric acid corrosion?
Inconel 718 has limited resistance to hydrochloric acid (HCl), especially at higher concentrations and temperatures; while its chromium (~19%) and nickel (~50–55%) provide good oxidation resistance, HCl is a strongly reducing acid, and corrosion rates can increase rapidly above room temperature or >5–10% HCl, making Inconel 718 unsuitable for continuous HCl service compared with high-Mo alloys.
Is Haynes® 282 more corrosion-resistant than Inconel 718 in a hydrochloric acid environment?
No-Haynes 282 is not significantly more resistant to hydrochloric acid than Inconel 718; although it offers excellent high-temperature strength and oxidation resistance, its lower molybdenum content means it still performs poorly in reducing acids like HCl, whereas alloys such as Hastelloy C-276 or Alloy 625 provide much lower corrosion rates and are preferred for hydrochloric acid environments.
inconel 718 vs haynes 282：Chemical Design Philosophy
| Alloy | Primary Design Objective |
|---|---|
| Inconel 718 | High strength, fatigue & creep resistance |
| Haynes 282 | Ultra-high temperature strength & weldability |
inconel 718 vs haynes 282： Chemical Composition Comparison (wt.%)
| Element | Inconel 718 | Haynes 282 |
|---|---|---|
| Nickel (Ni) | 50–55 | Balance (~57) |
| Chromium (Cr) | 17–21 | 19–21 |
| Molybdenum (Mo) | 2.8–3.3 | ~8.5 |
| Iron (Fe) | Balance | ≤ 1.5 |
| Aluminum (Al) | 0.2–0.8 | 1.5 |
| Titanium (Ti) | 0.65–1.15 | 2.1 |
| Cobalt (Co) | ≤ 1.0 | ~10 |
inconel 718 vs haynes 282： Corrosion Resistance in Hydrochloric Acid (HCl)
| Condition | Inconel 718 | Haynes 282 |
|---|---|---|
| Dilute HCl (<5%) at RT | Poor | Fair |
| Moderate HCl (5–10%) | Very poor | Poor |
| Hot HCl | Not suitable | Not suitable |
| Localized corrosion risk | Very high | High |
inconel 718 vs haynes 282：Typical Corrosion Rates (Indicative, mm/year)
| Alloy | Dilute HCl (RT) |
|---|---|
| Inconel 718 | > 5.0 mm/year |
| Haynes 282 | ~ 2.0–3.5 mm/year |
| Hastelloy C276 (reference) | < 0.5 mm/year |
inconel 718 vs haynes 282：Strength vs Corrosion Trade-Off (Buyer Perspective)
| Property | Inconel 718 | Haynes 282 |
|---|---|---|
| Yield strength (RT) | ~1030 MPa | ~760 MPa |
| Max service temp | 650 °C | 900+ °C |
| HCl resistance | Poor | Slightly better |
| Typical HCl usage | Not recommended | Limited, controlled |
Inconel 718 suppliers
At GNEE, Inconel 718 is available in various forms to meet diverse industrial needs:
Plates and Sheets (cold rolled and hot rolled)
Bars and Rods (round, square, hexagonal)
Tubes (seamless and welded)
Wires and Strips (for springs, fasteners, electrical applications)
Forgings and Custom Parts (according to drawings or specifications)
Specifications: UNS NO7718, WNR 2.4668, AFNOR NC19FeNb, JIS NCF 718, GOST ХН75МБТЮ, EURONORM NiCr22Mo9Nb, OR ЭИ602, BS NA 21.
Temperature Range: -423°F to 1300°F.
Testing and Documentation: Mill Test Certificates, EN 10204 3.1, Chemical Reports, Mechanical Reports, Destructive Testing Reports, Non-Destructive Testing Reports, PMI Test Reports, Visual Inspection Reports, Third-Party Inspection Reports, NABL Certified Laboratory Reports.
Packaging: Wooden crates, bubble wrap, steel strapping, or packaged according to customer requirements.
