Short answer
For high-temperature strength, assess Inconel 718; for aggressive chemical exposure, Hastelloy C-276 or C-22; for suitable marine duties, Monel 400 or K-500; and for low weight, titanium. These are starting points. The order must name the exact grade, final condition and requirements for the finished fastener. [1–8]
“Final condition” means the material’s processing state when supplied—for example, annealed, cold-worked or age-hardened where applicable. It affects the properties you can order and check. It is separate from a surface finish or coating.
If you already have an approved drawing, quote that requirement first. If you are still choosing a material, tell the supplier what the fastener will actually face. A useful offer should identify the proposed grade, explain any deviations and say what evidence will arrive with the parts.
Which material should you ask a supplier about?
Inconel, Hastelloy and Monel are trade names for nickel-alloy families. Titanium is a different metal. A request for “nickel alloy fasteners” narrows the search, but it still leaves several different purchases open.
Use this chart to start a discussion, then check the grade against your drawing and service conditions.
| Family | Grades to distinguish | Why a buyer might consider them | Resolve before ordering |
|---|---|---|---|
| Inconel | 625 and 718 | Corrosion resistance, hot service or high strength, depending on the grade | Is corrosion or strength driving the order? What final condition is required? |
| Hastelloy | C-276 and C-22 | Aggressive chemical exposure | Which chemical mixture, concentration and temperature will reach the fastener? |
| Monel | 400 and K-500 | Marine and selected chemical duties | Does the job need 400 or age-hardened K-500? Is seawater flowing, trapped or stagnant? |
| Titanium | Grade 2 and Grade 5 | Low weight and resistance to suitable corrosive environments | Is Grade 2 adequate, or does the design require Grade 5? What are the mating material and installation requirements? |
This is a shortlist, not a ranking of approved substitutes. The grade-specific points below explain why the second column matters. [1–8]
Inconel: 625 and 718 answer different questions
Inconel 625, UNS N06625, combines corrosion resistance with strengthening from its alloy chemistry. Inconel 718, UNS N07718, develops high strength through controlled heat treatment known as age hardening. A quote saying only “Inconel bolts” leaves both the grade and the condition unresolved. [1] [2]
For a hot joint, ask how much clamping force the connection must retain, at what temperature and for how long. A material’s resistance to surface oxidation does not tell you how much bolt load remains after months in service. Keep the drawing’s condition and mechanical requirements on the enquiry.
For a more detailed choice within this family, read Inconel 625 vs 718 fasteners. If the grade is already fixed, go straight to the Inconel 718 specification guide.
Hastelloy: describe the liquid, not just the industry
C-276, UNS N10276, and C-22, UNS N06022, are both corrosion-resistant nickel-chromium-molybdenum alloys. C-22’s higher chromium content improves resistance to oxidizing media compared with C-276. That makes the actual process mixture important; “chemical plant” is not enough information to choose between them. [3] [4]
For corrosion-resistant fasteners, send the chemical name, concentration, operating and cleaning temperatures, and known contaminants. Say whether the bolt is immersed, splashed or normally dry. Include liquid that can collect beneath the nut or washer. Haynes’ published corrosion diagrams are based on stated laboratory conditions, so an acid name alone cannot establish the result in your plant. [3] [4]
The Hastelloy vs Inconel guide covers that comparison in more detail.
Monel: 400 and K-500 are not interchangeable
Monel 400, UNS N04400, is a nickel-copper alloy that can be strengthened by cold working. K-500, UNS N05500, adds an age-hardening response that can produce greater strength and hardness. The supplied condition therefore matters as much as the family name. [5] [6]
Marine use does not mean immunity to every seawater problem. Special Metals reports that stagnant or slow-moving seawater can lead to fouling and pitting in K-500, and that aged K-500 is more susceptible to stress-corrosion cracking in some environments than alloy 400. Tell the supplier about trapped water, deposits and any sour-service requirement. [6]
If K-500 is specified, use the Monel K-500 ordering guide to clarify the final condition and inspection scope.
Titanium: choose the grade before comparing the weight
Grade 2, UNS R50400, is commercially pure titanium used in industrial corrosion service. Grade 5, UNS R56400 or Ti-6Al-4V, is a higher-strength titanium alloy. They are not two strength levels of an otherwise identical purchase. [7] [8]
For titanium components and fasteners, low weight can be valuable, but the selection also needs the service environment, load and temperature. Review the mating metals and installation method; replacing a nickel-alloy bolt with a lighter titanium bolt changes more than the mass. For Grade 5, ask the supplier to confirm the required condition and properties for the delivered part; the alloy name alone does not establish them. [8]
How do you choose a supplier?
Start with suppliers that can quote the exact grade and finished-part requirements. Ask whether they offer finished stock or made-to-order parts, who controls any required heat treatment and inspection, and which records will accompany the delivered lot.
A stockist may suit an urgent standard part. Drawing-specific work needs a supplier able to control the manufacturing and inspection steps. Shortlist suppliers by these answers, then compare prices. For a fuller check, use the special-alloy supplier qualification guide.
What should a fastener enquiry include?
You do not need to rewrite an approved drawing into a long form. Send the drawing and revision, then make the commercial requirements clear. If there is no drawing, start with a sketch, photographs or a written description; dimensions and acceptance requirements still need agreement before manufacture.
Include these details in your enquiry:
- The part: bolt, stud, nut, washer or another form; drawing or standard, size, thread, length and quantity per item.
- The material: exact grade or UNS designation, required final condition, and applicable material specification and edition.
- The finished part: dimensional tolerances, mechanical requirements, finish or coating, mating hardware and any manufacturing restrictions on the drawing.
- The service: actual exposure, operating temperature, load information available, and why an alternative is being considered.
- The delivery: destination, required date, documents, inspection scope and packaging or lot-separation needs.
For example, ASTM B348/B348M covers titanium bars and billets. It does not by itself specify every requirement for the finished titanium bolt made from that bar. Product requirements or the drawing must complete the order. [9]
Illustrative RFQ
Please quote 40 Alloy 625 hex bolts to drawing BF-104 Rev C: M12 × 1.75–6g, 60 mm length under the head, UNS N06625. Follow the drawing’s final-condition and finished-part requirements. Include the agreed material and inspection documents, heat/lot identification and delivery to our stated destination. List any deviation separately. Please quote mating nuts and washers as separate line items against their specified requirements.
Use your own drawing and agreed requirements in place of this example. If anything is still open, ask the supplier to identify it in the quotation.
No approved drawing? Ask the supplier to propose the material condition, dimensions and thread requirements, mechanical acceptance criteria and inspection documents. Have the person responsible for the equipment confirm those requirements before ordering. Record the agreed specification on the purchase order.
For dimensions or unusual geometry, see drawing-based special-alloy fasteners.
Can a cheaper or available alloy replace the specified one?
Sometimes—but “same size,” “higher strength” or “better corrosion resistance” is not enough to approve a change. Ask for the proposed alternative as a separate offer, with a list of differences. The person responsible for the design should approve a material change before it becomes the purchase requirement.
Three common offers show where the decision sits:
“We have 625 instead of 718”
Check the original reason for choosing 718, its final condition and required mechanical properties. A 625 bolt with the same thread is not automatically an equivalent high-strength part. Corrosion and hot-joint requirements also remain part of the review. [1] [2]
“Grade 5 titanium is stronger than Grade 2”
That statement does not settle a substitution. Compare the specified material, service compatibility, final condition and complete joint requirements. A higher strength value alone cannot approve the replacement. [7] [8]
“This Monel bolt has the same material certificate”
Read the grade and condition on the offer and the report. A record for the starting material does not show that the finished bolt received the required treatment, has the specified threads or passed the agreed tests. Link those records to the delivered lot. [5] [6] [9]
Do not lose the nut and washer while comparing the bolt. They carry the load too. Confirm their specifications, mating materials and any lubricant or treatment to prevent thread seizure, often called galling. Ask for tightening instructions that match the agreed assembly and lubricant; do not assume an existing torque value applies after a material or coating change. [11] See the bolt and nut pairing guide.
How do you compare prices and lead times fairly?
Compare technically acceptable offers against the same scope before choosing the lowest total. There is no useful universal price order for Inconel, Hastelloy, Monel and titanium fasteners: size, grade, quantity and manufacturing route can change the quotation.
Ask each supplier to make these items visible:
| Quote item | What to compare |
|---|---|
| Grade and final condition | Exact match to the enquiry; any alternative separately identified |
| Product and quantity | Each bolt, nut and washer line; minimum quantity per size and grade |
| Manufacture | Standard geometry or drawing-specific work; any proposed change to the drawing |
| Inspection and documents | Which tests and reports are included, their sampling scope, and any extra charges |
| Availability | Finished parts in stock, material in stock, or material still to be sourced |
| Delivery | Time to shipment, transport allowance and the date or event that starts the lead time |
| Delivered cost | Currency, delivery and payment terms, packaging, freight, and agreed taxes or duties as well as the part price |
“Material in stock” is not the same promise as “finished bolts ready to ship.” Machining, treatment, inspection and document release may still follow. For a shutdown order, ask for a shipment date tied to the actual scope, not simply an attractive number of weeks.
For a small order, ask whether the supplier can quote standard geometry alongside the requested custom version. Keep both offers technically separate. An unnecessary special feature can add cost; a required feature must not disappear to meet a target price.
Buying aerospace fasteners? Start with the approved requirement
Inconel 718 and titanium alloys have aerospace applications, but buying an alloy used in aircraft does not make the delivered fastener eligible for flight hardware. Send the required part number, drawing revision, specification and purchasing or approval requirements at the first enquiry. [2] [8]
For U.S. type-certificated aircraft replacement parts, FAA guidance treats quality, eligibility and traceability as connected questions. A material test certificate alone does not answer them all. The required evidence depends on the part and its approved purchasing route. [10]
Ask what supplier or process qualifications, lot records, first-article evidence and release documents your order calls for. Check the proposed supplier against those requirements. A general industrial quotation and an aerospace-qualified supply route are different offers, even if the alloy and dimensions appear identical.
Which documents should arrive with the fasteners?
Agree the document package while requesting the quote. Finding out after manufacture that the order needs additional testing can delay release or leave the original lot without the evidence you need.
For an industrial order, connect three things:
- Material identity: the grade, material specification and reported results on the material/inspection certificate, including EN 10204 3.1 where ordered.
- Finished-part checks: the dimensional, thread and mechanical results required by the order, plus any specified treatment or additional test records.
- The delivered lot: labels or markings and records that connect the received items to the relevant heat and manufacturing lot.
A heat number identifies a material heat. One heat can feed more than one manufacturing or treatment lot. Keep the link through processing and packing, rather than assuming a shared heat number means every bolt has the same processing history.
BYBOLT’s delivery baseline includes heat-number traceability, MTC / EN 10204 3.1 documentation and mechanical testing. Threaded products include sampled GO/NO-GO gauge checks. The quotation should identify which results cover the starting material, which checks cover the finished fasteners, and the sampling scope. Agree any additional inspection before ordering; sampled testing does not mean every item is tested individually.
At receiving, match quantities, item and lot labels, and supplied records to the purchase order. Check the agreed sample for dimensions, thread compliance, finish and visible damage. Review the required grade, condition and test results before releasing the lot. Hold any affected lot if the parts or records do not match. The MTC, PMI and inspection-report guide explains what each type of evidence can establish.
Fastener inventory management for repeat orders
For repeat orders, keep different grades, drawing revisions and lots separate in your stock. A bin labelled “M12 nickel bolts” cannot distinguish 625 from 718, or one approved drawing revision from another.
Keep the part number, revision, size, grade, condition and lot identity with the stock. Retain the certificate link when splitting a delivery into smaller packs. Separate unreleased or disputed parts from stock available for use.
Set the reorder point around consumption during the actual replenishment time, plus a buffer that suits the cost of a shortage. For illustration, using four parts per week with a six-week replenishment time consumes 24 parts; an eight-part buffer puts the reorder point at 32. This is a planning example, not a supplier lead-time promise.
For infrequent maintenance parts, the approved spare requirement and shutdown plan may be more useful than a weekly average. Discuss repeat quantities, likely order dates and whether any stocking arrangement is available. Confirm any stocking arrangement in writing, including who holds the stock and when it can be released.
Ready to request a quote?
Send BYBOLT your drawing or written part description, exact grade and condition, quantities, required date and destination. Add the service information if you want a material alternative reviewed, and list the documents needed at delivery.
If you are choosing between grades, send the current specification and explain the problem you want to solve: corrosion, loss of clamping force, weight, availability or cost. Ask for the proposed alternative and its differences alongside the original requirement.
Already specifying a product? Start with Alloy 625 hex bolts, Alloy 718 hex bolts or C-276 hex bolts, and keep the drawing’s requirements with the enquiry.
INCONEL and MONEL are trademarks of Special Metals; HASTELLOY is a trademark of Haynes International. The names identify alloy families, not BYBOLT affiliations or product approvals.