Buying finished hex bolts? See Inconel 625 Hex Bolts (UNS N06625) for dimensions, order requirements and quotation. Use this guide to define the B446 material condition and separate finished-part acceptance.
“Inconel 625 bolts to B446” appears precise because it includes both a grade and a standard. It still leaves two important questions unanswered: which material condition is required, and how will the finished bolts be accepted?
For other product forms, use stud bolts or custom fasteners to request review of the material, geometry and condition. For raw material only, browse raw-material forms.
Specify Inconel 625 / UNS N06625 with the applicable product-form specification and condition, then define the finished fastener separately. ASTM B446 concerns rod and bar. It does not turn a material certificate into proof that a bolt meets its drawing, thread tolerance and finished-part requirements. [1]
B446 contains three N06625 conditions
The published scope of ASTM B446-26 distinguishes the following conditions. The grade number here belongs to the raw-material specification; it is not a universal bolt property class.
| Designation | Condition | Question to resolve in the order |
|---|---|---|
| Grade 1 | Annealed | Record the annealed condition and the applicable acceptance requirements |
| Grade 2 | Solution annealed | Record the solution-annealed condition and the properties required by the hot-joint design |
| Grade 3 | Solution annealed and cold worked | How will the specified worked condition and required properties be preserved through manufacture? |
The scope associates Grade 2 with higher-temperature creep and rupture considerations and Grade 3 with higher-strength needs. Those descriptions help identify the intended condition; they do not set the allowable temperature or load for a particular bolt. B446 also cautions that hot working or reannealing can change properties significantly. [1]
Check that the certificate belongs to the ordered form
A plate certificate and a bar certificate may both identify N06625 while referring to different product specifications. ASTM B443 covers plate, sheet and strip; B446 covers rod and bar. Select the requirement that fits the approved manufacturing route rather than accepting any certificate with “625” on it. [2]
If a supplier proposes a different starting form, record the proposal and review it against the drawing and acceptance requirements. For a bar-machined part, ask which certified bar lot was used and what processing followed. For a forged part, have the supplier identify the applicable material and forging requirements instead of assuming a rod-and-bar callout covers every stage.
Separate the bar result from the bolt result
The material certificate supports the facts and tests it actually reports. The finished-part inspection must address dimensions, threads and any required final mechanical tests. A material result from before additional processing may not establish the delivered fastener’s properties.
Special Metals presents 625 property information by condition. Its typical data are useful for understanding the material, but they should not be copied into a purchase order as though they were guaranteed acceptance values. [3]
Before ordering, agree the finished-fastener standard and edition or drawing acceptance requirements, final condition, dimensional and thread tolerances, required tests with sampling and limits, and the records connecting material heat to finished lot. Specify tensile, hardness or other tests where the agreed acceptance basis requires them; a list of possible tests is not an inspection plan.
Every BYBOLT delivery includes an MTC / EN 10204 3.1 certificate, heat-number traceability and mechanical testing. Threaded products include sampled GO / NO-GO gauging. Agree any additional document type, PMI or third-party witnessing at quotation; methods and acceptance criteria follow the agreed specification.
Example: make a bar-machined bolt enquiry quotable
Hex bolts to drawing [number/revision], Alloy 625 / UNS N06625. Bar requirement: ASTM B446-[agreed edition], Grade [approved grade]. Final fastener condition: [requirement]. Thread system and tolerance: [drawing callout]. Finished-fastener standard or drawing acceptance basis: [approved requirement]. Tests, sampling and acceptance limits: [approved schedule]. Identify the material heat and finished lot on the release documents. Submit alternate conditions or routes as deviations.
Complete the bracketed entries with the design owner. In particular, select the finished-fastener basis for the actual size and product rather than placing a list of possible standards on the order. The fastener standards guide explains that distinction.
Keep the environmental approval attached to the selection
A 625 callout should retain any conditions on which its selection depended. If the design addressed a seawater crevice, preserve that exposure description when reviewing an alternate product. If it addressed sustained hot load, preserve the condition and time-dependent requirements. The seawater and preload-retention articles cover those separate decisions.
Include the mating parts in the enquiry
Check the 625 designation against the order, and attach the controlled drawing for the hex bolts being purchased. For a stud, nut and washer set, list each component’s material, condition and requirements. The bolt’s callout should not silently become the nut or washer specification.
If the reason for choosing 625 is still unclear, start with the nickel-alloy fastener selection guide; this specification guide assumes that the material choice has been made.