“Inconel bolt” is common language in enquiries, but it is incomplete as a purchase description. Two quotations can use that phrase while offering different alloys, heat treatments and mechanical properties. The same trade name also appears in enquiries for other fastener forms, including screws, studs and nuts.
INCONEL is a Special Metals trademark used for a family of nickel-chromium alloys. It is not one grade or a finished-fastener standard. For purchasing, establish the numbered alloy and UNS first, then the required condition and part specification. Special Metals identifies Alloy 625 as UNS N06625 and Alloy 718 as UNS N07718. [1] [2]
For example, “Inconel 625 (UNS N06625) fasteners” identifies a specific alloy where “Inconel fasteners” does not. This is a naming example; the condition and finished-part requirements still need to be specified.
For a hex-head part with an agreed grade, use the Inconel 625 hex bolt page or Inconel 718 hex bolt page for dimensions, thread requirements and enquiry details.
Read the quotation one term at a time
| Quotation wording | What it identifies | What it leaves open |
|---|---|---|
| Inconel | A trade-name family | The specific alloy |
| Inconel 718 / UNS N07718 | The alloy designation | Product form, processing condition and acceptance requirements |
| Solution treated and aged | A general treatment description | The controlling treatment requirements and required final properties |
| A bolt drawing and revision | The ordered geometry and any requirements actually written on that drawing | Material condition or acceptance requirements omitted from the drawing |
UNS is useful for resolving an ambiguous name. It does not certify the particular bolt, identify the mill that made it or establish that the finished threads meet the drawing.
Why 625 and 718 are not interchangeable names
The producer describes 625 as primarily solid-solution strengthened and 718 as age hardenable. That difference affects the questions a buyer must ask about condition. An unspecified “Inconel” substitution can therefore change more than the chemistry. [1] [2]
If a quotation changes the requested 625 to 718, ask for a stated deviation and engineering review. Do not accept it because the supplier describes both as corrosion-resistant nickel alloys. The 625 versus 718 guide addresses that selection decision separately.
How to clarify an incomplete enquiry
Suppose an enquiry says: “Inconel hex bolts, M12 × 60, 100 pieces.” If the drawing does not identify an alloy, “high-temperature grade” is not enough. Ask the supplier to state what it proposes, and have the design owner approve it before ordering:
Please identify the proposed alloy and UNS, feedstock specification and final fastener condition. Quote to drawing [number/revision], including the specified thread tolerance. State the finished-part acceptance basis and list all deviations separately. The design owner will approve the alloy and condition before order release.
This example is a clarification request, not a completed bolt specification. It gives the supplier a way to expose missing information without selecting the design requirements on the buyer’s behalf. Once approved, replace the open items with exact requirements.
When the brand name itself matters
Some contracts require a named producer or an approved source. If that applies, record it separately from the alloy designation and require the agreed origin records. A generic Alloy 625 material description does not prove Special Metals origin; equally, a trade name on a quotation does not replace heat traceability.
Compare the purchase order, material certificate and part identification. Resolve a missing UNS, conflicting condition or unexplained source before acceptance. The MTC, PMI and inspection-report guide explains what those records can establish.
Use the agreed designation in the purchase order
The material references for 625 and 718 can accompany the enquiry. Carry the approved alloy, condition and drawing revision into the RFQ and purchase order. For 625 hex bolts or 718 hex bolts, identify the head, dimensions and thread requirements alongside that material callout.
Once the alloy name is clear, use the nickel-alloy fastener selection guide to work through service conditions, the finished part and the mating components.