Incoloy 800, 800H and 800HT are nickel-iron-chromium alloys used where heat resistance and resistance to oxidation or carburization are required. They belong to the wider Incoloy family. Their similar names do not establish that they are interchangeable in a component specification.

The distinction matters when purchasing replacement material or comparing supplier quotations. A quotation described only as “Incoloy 800 series” leaves the required grade unresolved. The purchase specification should identify the UNS designation and delivery condition.

How the Three 800-Series Grades Differ

The three grades share the same specified nickel and chromium limits. Their differences include carbon control and, for 800HT, tighter aluminum and titanium requirements. Grain size and heat treatment also contribute to the elevated-temperature performance of the H grades.

This comparison shows selected distinguishing requirements. Acceptance also depends on the remaining composition limits and the applicable product specification.

Temperature Selection Requires More Than a Maximum Value

800H and 800HT were developed for improved resistance to creep and stress rupture during elevated-temperature service. Creep is gradual deformation under sustained load; stress rupture concerns failure after exposure to that load over time.

For an equipment inquiry, distinguish normal metal temperature from short excursions. State whether the component carries a sustained load and whether operation involves repeated heating and cooling. Furnace atmosphere also matters when oxidation or carburization is a concern.

A single temperature figure cannot establish grade suitability. The equipment designer must assess the selected material against the required service life and applicable design rules. An alloy's resistance to oxidation alone does not establish its allowable load at that temperature.

Where the 800 Series Is Used

Typical uses include furnace components and electrical heating-element sheaths. The family also appears in petrochemical heating equipment, including cracking tubes and associated headers. The selected grade depends on the component's operating conditions and material specification.

During replacement procurement, an existing part number can help identify the equipment, but the material requirement should come from the approved drawing or material schedule. A change of grade requires technical review, even when the replacement has identical dimensions.

DZX's Incoloy Alloy category provides the starting point for product inquiries. Include the required form in the inquiry so that dimensional requirements and inspection scope can be reviewed for that product.

What to Check in a Supplier's Offer

Start with the material designation. An offer for N08800 should not be accepted against an N08810 requirement without an approved change. Likewise, chemistry that overlaps two grades does not establish that every requirement of both grades has been met.

• Product specification: Name the standard applicable to the ordered form, together with its required edition. Add project requirements separately so they remain visible during quotation review.

• Delivery condition: State the required heat-treated condition. If grain size is an acceptance requirement, identify the required result and the document on which it must be reported.

• Dimensions: Distinguish finished component dimensions from supplied material dimensions. Include tolerances that affect subsequent fabrication or assembly.

• Inspection documents: Agree on the certificate type and required test results before placing the order. Any additional examination should have an identified method and acceptance criteria.

Compare quotations against these requirements before comparing price. A lower offer may cover a different delivery condition or exclude an examination required by the project.

DZX Manufacturing and Supply Coordination

DZX's manufacturing facilities include alloy melting and annealing, supported by precision-processing operations. Cutting and CNC machining capabilities allow buyers to discuss preparation requirements alongside the material inquiry. The production route for an individual grade and product form is reviewed against the order specification.

Raw-material purchasing is supported by established supplier relationships and incoming verification. Chemical analysis and mechanical testing are part of the company's inspection capabilities. For buyers coordinating several purchase items, this provides a basis for reviewing material requirements and processing scope through the same supplier.

For distributor orders, separate the quantity required for each customer project from stock replenishment. Identify which items require dedicated inspection records before production is scheduled. This helps prevent material intended for general stock from being allocated to a project with additional acceptance requirements.

Receiving and Releasing Material to Production

On receipt, match the package identification to the purchase order and the accompanying certificate. Check that the reported grade agrees with the ordered designation, then review the results required by the specification. Resolve missing information before releasing material for fabrication.

Keep heat identification attached to the material after cutting or repacking. Where a shipment contains several heats, receiving records should show which certificate belongs to each quantity. This is particularly useful for distributors splitting a delivery between customers.

Questions That Often Arise During Procurement

1. Can Incoloy 800H be supplied in place of 800HT?

Only when the offered material meets all requirements of the ordered designation and the substitution is accepted by the responsible technical authority. A supplier's general statement that the grades are similar is insufficient.

2. Is a chemical analysis enough to identify an H-grade delivery?

No. Review the delivery condition and other requirements of the applicable specification as well. Ask for clarification if the certificate lists the chemistry but leaves required processing or inspection information unresolved.

3. Does an alloy's inclusion in a design code certify the finished component?

No. Material eligibility and finished-equipment compliance are separate matters. The project must establish the applicable code edition and component requirements; these should be communicated during purchasing.

4. What should an initial inquiry to DZX include?

Provide the UNS designation and product specification with the required dimensions. Add the order quantity and delivery destination, then attach any project-specific inspection requirements. If a material designation is unclear, include the relevant drawing or existing certificate for review before an offer is finalized.