GH4169 vs Inconel 718: Are They the Same Grade? Chinese Alloy Equivalents Explained

GH4169 vs Inconel 718: Are They the Same Grade? Chinese Alloy Equivalents Explained

Quick answer: Yes — GH4169 is the Chinese (GB) designation for the same Ni-Fe-based superalloy known internationally as Inconel 718 (UNS N07718, W.Nr. 2.4668). The nominal chemistry is essentially identical: Ni 50–55%, Cr 17–21%, Nb+Ta 4.75–5.5%, Mo 2.8–3.3%, Fe balance. In practice, "equivalent" does not always mean "identical" — the differences lie in which standard governs your order, product forms available, testing conventions, and certification expectations, not in the metallurgy.

Why Chinese Grade Numbers Confuse International Buyers

Chinese superalloys use the "GH" prefix (from gaowen hejin, high-temperature alloy) followed by a number: GH4169, GH625, GH3030, GH4145 and so on. Because these numbers do not map visibly to Western trade names, buyers sourcing from Chinese mills often cannot tell whether a quoted grade is a true equivalent, a derivative, or an entirely different alloy. The table below resolves the most common superalloy equivalences.

Common Chinese Superalloy Equivalents

For sourcing purposes, the practical rule is simple: specify both the international designation and the UNS number on drawings and purchase orders, and name the governing standard (e.g., "Inconel 718 / UNS N07718 per ASTM B637"). Then the Chinese designation becomes irrelevant to correctness — any competent mill will supply to the named standard.

GH4169 / Inconel 718: Composition and Properties

Room-temperature mechanical properties in the solution-treated + double-aged condition are likewise aligned: yield strength ≥ 1,030 MPa, tensile strength ≥ 1,275 MPa, elongation ≥ 12% in bar and forging forms. The alloy retains useful strength to about 650 °C and remains ductile at cryogenic temperatures to −253 °C, which is why it serves in both gas-turbine disks and liquid-hydrogen hardware.

Where Real Differences Appear

1. Which standard governs the certificate. Material bought to GB/T 14993 arrives with Chinese-standard test formats; international projects usually require ASTM B637 or AMS 5662 documentation. A good mill can certify to either — but you must ask before ordering, not after.
2. Aerospace grades vs commercial grades. "GH4169" alone covers a range of quality levels. Aerospace buyers should name AMS 5662/5663 (bar and forgings) or AMS 5596/5597 (sheet) explicitly and require full traceability to the melt.
3. Testing condition conventions. Chinese practice and ASTM practice both test in the aged condition, but sample orientation and lot definitions can differ — a detail that matters for NACE MR0175 sour-service qualification.
4. Size ranges and minimum orders. Chinese mills often offer wider plate and larger forging capacities than Western distributors, while Western service centers offer better small-quantity availability.

How to Source GH4169 / Inconel 718 Safely

• Write the purchase order around the standard, not the trade name: "Inconel 718, UNS N07718, per ASTM B637, condition: solution treated + double aged."
• Require EN 10204 3.1 certificates minimum, with spectrometric chemistry and mechanical tests in the aged condition, heat-number traceable.
• For sour service, require NACE MR0175/ISO 15156 compliance, including hardness ≤ 40 HRC in the qualified condition.
• For aerospace, specify AMS grade and request third-party (3.2) certification.
• Verify equivalences with the mill in writing before contract — ask for a cross-standard compliance statement if your project mixes Chinese and Western documentation.

Frequently Asked Questions

Is GH4169 exactly the same as Inconel 718? Metallurgically yes — the chemistry and properties match within the same specification windows. The differences are in governing standards, certification formats, and quality-level conventions, not in the alloy itself.

What is the ASTM equivalent of GH4169? UNS N07718, commonly supplied per ASTM B637 (bar and forgings) or AMS 5662/5663 (aerospace bar), and per AMS 5596/5597 for sheet.

Is Inconel 718 / GH4169 suitable for sour oilfield service? Yes, in the properly aged condition it is qualified per NACE MR0175/ISO 15156 for H2S environments, with hardness typically controlled at or below 40 HRC.

Which standard should I put on my purchase order when buying from China? The one your project requires. For international projects, specify UNS N07718 per ASTM B637 or the relevant AMS grade, and require EN 10204 3.1 or 3.2 certification with full heat traceability.