Cobalt Alloy Grades, Properties & Product Forms
Basic Description
Sagiant Piping Industries supports enquiries for cobalt-base alloys across distinct families — wrought heat-resistant L605/Haynes 25 (UNS R30605) and Haynes 188 (R30188), high-strength/spring and medical MP35N (R30035) and Elgiloy (R30003, Werkstoff 2.4711), and cast/deposit wear grades Stellite 6 (Co-Cr-W) and Stellite 21 (Co-Cr-Mo) — as bar, sheet/plate, wire, fasteners, wear components and hardfacing consumables. These are different material families with different properties, so wear, high-temperature strength, spring/fatigue performance and medical use are described per grade and condition rather than as one combined claim. Material is offered by grade, route and condition against the applicable AMS/ASTM references, with acceptance limits and editions confirmed per order and EN 10204 3.1 or 3.2 documentation. Stellite, HAYNES, MP35N and Elgiloy are trademarks of their owners; Sagiant is an independent supplier and stockist, and the verified range is mainly solid, flat, wire and wear products rather than seamless pipe.
Cobalt alloys: grade guide, chemistry, properties, standards and RFQ data
Grade-by-grade composition, condition-noted mechanical and physical reference data, standards by grade/form/route, wear and fabrication guidance for the six detailed grades, with a wider family directory. Producer reference values are shown separately from specification acceptance limits confirmed on the certificate; availability is confirmed on review.
Technical Specification
| Parameter | Specification |
|---|---|
| Grades detailed | L605/Haynes 25, Haynes 188, MP35N, Elgiloy, Stellite 6, Stellite 21 (below); wider family in the directory |
| Families | Wrought heat-resistant (L605, 188), high-strength/spring & medical (MP35N, Elgiloy), cast/deposit wear (Stellite) |
| Product forms | Bar, forging, sheet/plate/strip, wire, fasteners, wear components and hardfacing consumables — by actual grade & route |
| Conditions | Annealed, cold-worked, aged, cast or deposited — grade- and route-specific |
| Basis | Producer reference data; specification acceptance limits, form, condition and edition confirmed per order |
The verified technical range is mainly solid, flat, wire and wear products rather than seamless pipe. Cobalt-containing steels, cobalt-bonded carbides and magnets are not covered as cobalt-base metallic grades here.
Chemical Composition (wt %)
| Grade | Co | Cr | Ni | W | Mo | Other (spec-controlled) |
|---|---|---|---|---|---|---|
| L605 / Haynes 25 | Balance | 19.0–21.0 | 9.0–11.0 | 14.0–16.0 | — | Fe ≤3, Mn 1.0–2.0, Si, C ~0.1 & residuals per spec |
| Haynes 188 | Balance | 20.0–24.0 | 20.0–24.0 | 13.0–16.0 | — | La 0.02–0.12, Fe ~3, Mn, Si, C, B per spec |
| MP35N | 33.0–37.0 | 19.0–21.0 | 33.0–37.0 | — | 9.0–10.5 | Fe, Ti, C & residuals per spec (melt route identified) |
| Elgiloy | 39.0–41.0 | 19.0–21.0 | 14.0–16.0 | — | 6.0–8.0 | Fe Bal, Be ≤0.10 (max), Mn 1.5–2.5, Si ≤1.2, C ≤0.15, P ≤0.015, S ≤0.015 |
| Stellite 6 (cast/deposit) | Balance | ~28 | — | ~4.5 | — | C ~1.0–1.2, plus Fe/Si/Mn per grade (deposited/cast basis) |
| Stellite 21 (Co-Cr-Mo) | Balance | 26–29 | ≤3 | — | 4.5–6 | C <0.35, plus Fe/Si/Mn per grade |
Stellite 6 (Co-Cr-W) and Stellite 21 (Co-Cr-Mo) are different alloys and are no longer combined. Elgiloy beryllium is a 0.10% maximum (not a 0.05–0.10% range), and “biocompatible” is not a compositional limit. Specification limits, nominal composition and heat analysis are different datasets; the certificate governs.
Grade identity, designations & directory
| Grade / group | UNS / designation | Notes |
|---|---|---|
| L605 / Haynes 25 | R30605 (2.4964) | One alloy with aliases; AMS 5537/5759, ASTM F90 (medical) |
| Haynes 188 | R30188 | Co-Ni-Cr-W with lanthanum |
| MP35N | R30035 | Co-Ni-Cr-Mo; producer/low-Ti variants distinguished |
| Elgiloy | R30003 (2.4711) | Spring alloy; ASTM F1058 covers R30003 and R30008 (Conichrome) as distinct grades |
| Stellite 6 / 6B / 6K | Co-Cr-W | Wrought 6B (AMS 5894) is distinct from cast 6 — cast properties are not transferred to wrought |
| Stellite 21 | Co-Cr-Mo | Distinct from Stellite 6 |
| Wider directory | Stellite 1/3/4/12/25/190/250/694, Tribaloy T-400/T-800, ULTIMET (R31233), NS-163 | Catalogue reference; availability, chemistry & datasets confirmed on enquiry |
| Co-Cr-Mo implant family | F75 (cast), F799 (forged), F1537 (wrought) | Routes not interchangeable; edition & route verified |
Aliases do not inflate the grade count, and a matching designation does not establish identical melt practice, heat treatment, product form, mechanical acceptance or code/customer approval. Tribaloy and MP159 (a nickel-cobalt alloy) are assessed on their own basis, not silently treated as cobalt-base.
Mechanical Properties
| Grade (condition) | Tensile (MPa) | Yield 0.2% (MPa) | Elong. % | Hardness |
|---|---|---|---|---|
| L605 (annealed) | ~1010 | ~445 | ~52 | — |
| 188 (annealed) | ~960 | ~464 | ~50 | — |
| MP35N (cold-worked + aged) | ~1795 | ~1620 | ~8 | Condition-dependent |
| Elgiloy (aged) | ~1900 | ~1550 | ~5 | Condition-dependent |
| Stellite 6 / 21 (cast/deposit) | Wear grades characterised by hardness & wear tests, not annealed tensile | Per grade & condition | ||
Cold-worked/aged strengths depend on the exact reduction and aging cycle; the former 50/55 HRC “maximum” figures are replaced by condition-dependent values against a specification basis. Elevated-temperature tensile, creep and stress-rupture (for L605/188), fatigue and stress-relaxation (for springs/fasteners) are supplied with the applicable qualified dataset, otherwise identified as unavailable.
Physical Properties
| Grade | Density | Notes |
|---|---|---|
| L605 / Haynes 25 | ~9.13 g/cm³ | Solid-solution |
| Haynes 188 | Per producer datasheet | Solid-solution |
| MP35N | ~8.43 g/cm³ | Multiphase, cold-work + age strengthened |
| Elgiloy | Per producer datasheet | Elastic modulus quoted as ~221 GPa (32,000 ksi) — confirm against the producer’s 190 GPa figure |
| Stellite 6 / 21 | Per grade datasheet | Cast/deposit; hardness-driven |
Modulus, thermal conductivity, specific heat, resistivity, expansion and magnetic permeability follow each grade’s own temperature series and are supplied per grade rather than generalised. “Non-magnetic” is not asserted family-wide — permeability is given per grade and condition where relevant.
Standards by Grade, Form & Route
| Grade | References by form / route |
|---|---|
| L605 / Haynes 25 | AMS 5537 (flat), AMS 5759 (bar); ASTM F90 (medical material, identified separately from aerospace) |
| Haynes 188 | AMS 5608 (flat), AMS 5772 (bar/forging) |
| MP35N | ASTM F562 (wrought implant material), AMS 5844 (round bar) — neither is a complete finished-fastener standard |
| Elgiloy | ASTM F1058 (R30003/R30008); AMS 5833 is not a universal spring standard |
| Stellite (hardfacing) | Exact consumable classification & process (cast rod, bare wire, covered electrode, powder or deposit) — “AWS A5.21” alone is insufficient |
| Stellite 6B (wrought) | AMS 5894 |
| Fasteners | Drawing, thread, dimensions, processing, mechanical acceptance & inspection stated separately from the bar material spec |
Generic ASTM B-series / ASME SB references are not added merely because a grade is cobalt-based. A dimensional standard does not certify the material, and a weld-deposit designation is kept separate from bulk material.
Wear & Hardfacing (Stellite / Tribaloy)
| Aspect | Consideration |
|---|---|
| Condition | Deposited (overlay), cast and wrought stated separately — cast Stellite 6 properties are not transferred to wrought 6B/6K |
| Test basis | Abrasion / adhesive wear / cavitation method, counterface or abrasive, load and temperature recorded with the result |
| Overlay | Substrate, dilution, overlay thickness, machining allowance and hardness inspection location |
| Hot hardness | Added where available; hardness is condition-dependent, not a single value per family |
Tribaloy T-400/T-400C/T-800/T-900 have separate compositions and hardness ranges and are not assumed identical; applied hardfacing capability is confirmed on review rather than presented as universally stocked.
Available Forms, Sizes & Dimensions
| Form | Basis |
|---|---|
| Bar / rod | Diameter, length, tolerances, finish & condition by grade |
| Sheet / strip / plate | Thickness, width, length & tolerances stated per product category (sheet and plate ranges kept distinct) |
| Wire / spring | Diameter, temper & condition; medical/engineering wire distinguished |
| Fasteners | Part/drawing standard, thread class, processing & acceptance tests |
| Wear components / hardfacing | Cast rod, wire, powder or deposited layer with substrate & dilution |
| Tubing (medical, where offered) | Actual OD × wall & tolerances — not a pipe schedule |
No generic schedule chart is added to satisfy a piping keyword: any tubular offer needs a route, material specification and testing basis first, and unsupported forms are marked “custom dimensions subject to technical review”. Schedule thickness is not an allowable pressure, and a cobalt grade is not implied to be pressure-approved.
Service, Corrosion & Temperature
| Aspect | Consideration |
|---|---|
| High-temperature grades | L605 and 188 retain strength and oxidation resistance at elevated temperature; oxidation, useful loaded service, creep and short-exposure limits are stated separately with exposure conditions, not one shared figure |
| Spring / medical grades | MP35N and Elgiloy characterised by strength, fatigue and corrosion, not a high-temperature rating |
| Corrosion modes | General corrosion, pitting, crevice, stress corrosion, galvanic, erosion-corrosion and high-temperature oxidation/sulfidation assessed separately with media, concentration, temperature and duration |
| Wear grades | Stellite/Tribaloy selected by wear mechanism and counterface, not a corrosion rating |
Universal “seawater”, “acid-proof”, sour-service or implant-suitability claims are avoided; each is tied to sourced test results and limitations.
Fabrication
| Family | Guidance |
|---|---|
| Wrought heat-resistant (L605, 188) | Forming condition, work hardening, machining tooling/cooling, joining process & filler, cleanliness, heat input/interpass and inspection |
| Cold-worked spring (MP35N, Elgiloy) | Cold reduction and aging sequence; welding a strengthened part requires evaluating local property loss and reprocessing |
| Cast / overlay wear (Stellite, Tribaloy) | Overlay/substrate procedure qualification, dilution, distortion/cracking risks & hardness inspection |
| Safety | Process-appropriate dust/fume handling per the producer safety data sheet |
Cast wear alloys, cold-worked springs and wrought heat-resistant grades are not fabricated by one generic instruction; a qualified procedure governs shop practice.
Medical, Testing & Documentation
| Item | Scope |
|---|---|
| Medical material | Exact implant-material specification, grade and condition identified (e.g. ASTM F90, F562, F1058, F1537); a material’s medical use does not qualify every finished device |
| Mechanical | Room-temperature tensile, hardness and other specified tests per contracted method & acceptance criteria |
| PMI | Confirms alloy identity within the instrument/method capability; does not establish complete chemistry |
| Certification | EN 10204 3.1 (manufacturer) vs 3.2 (independent/third-party); document type does not inherently require every test |
Biocompatibility testing is listed only where the service, scope and supporting documentation are established; contracted tests and acceptance criteria are agreed at ordering with heat/lot traceability.
Product Range
The cobalt alloys range can be supplied with related pipes, tubes, butt weld fittings, forged fittings, flanges, fasteners and custom fabricated items where required by the BOQ.
Applications
For dimensional references, see the Pipe Schedule & Fittings Guide. For related supply, review Pipes & Tubes, Butt Weld Fittings, Forged Fittings and Flanges.
Types of Products
| Type | Description |
|---|---|
| Pipes & Tubes | Seamless, welded and large-diameter supply |
| Fittings | Butt weld, forged and fabricated fittings |
| Flanges | Forged flanges and special machined items |
| Plates / Bars / Round Bars | Subject to grade and project availability |
Available Forms
Related Pages
Calculate approximate metal weight before sending RFQ
Estimate pipe, tube, bar, plate and hollow section weight using material density presets, then share the result with your requirement.
Frequently Asked Questions
What is the difference between Stellite 6 and Stellite 21?
They are different alloys. Stellite 6 is a Co-Cr-W grade (chromium ~28%, tungsten ~4.5%, higher carbon) used for general wear and hardfacing; Stellite 21 is a Co-Cr-Mo grade (chromium 26–29%, molybdenum 4.5–6%, carbon below ~0.35%, nickel below ~3%). They have different compositions and condition-dependent hardness and are no longer shown as one “Co-Cr-W” row. Confirm which grade a drawing requires.
Is cast Stellite 6 the same as wrought 6B?
No. Wrought Stellite 6B (and 6K) is a distinct wrought product with its own identity and standard (for example AMS 5894 for 6B), and its properties are not the same as cast or deposited Stellite 6. Cast/hardfacing data are not transferred to wrought grades — the route and condition are stated for each.
What is the beryllium content of Elgiloy?
The producer wire datasheet specifies beryllium as a 0.10% maximum, which does not establish a 0.05% minimum — so it is shown as Be ≤0.10%, not a 0.05–0.10% range. Elgiloy also carries controlled Mn, Si, C, P and S, and its Werkstoff number is 2.4711. The contracted specification is confirmed before order.
Are these cobalt alloys biocompatible / medical grade?
Medical supply is qualified only against the exact implant-material specification, grade and condition (for example ASTM F90, F562, F1058 or F1537). A material being used in medical devices does not mean every finished part or device is qualified, so we identify the actual specification and documentation rather than making a blanket “biocompatible” claim, and biocompatibility testing is listed only where the scope is established.
Which standards apply to these grades?
By grade and route: L605/Haynes 25 to AMS 5537/5759 and ASTM F90 (medical); Haynes 188 to AMS 5608/5772; MP35N to ASTM F562 (material) and AMS 5844 (round bar) — neither is a complete finished-fastener standard; Elgiloy to ASTM F1058 (which covers R30003 and R30008); Stellite hardfacing to the exact consumable classification and process, with wrought 6B to AMS 5894. The form, condition and adopted edition are confirmed per order.
Do you supply cobalt-alloy pipe?
The verified range is mainly bar, sheet/plate, wire, fasteners, wear components and hardfacing — not standard pipe. We do not publish a generic schedule chart for cobalt grades; a tubular product (for example thin medical tubing described by actual OD × wall) needs a defined route, material specification and testing basis first. Schedule thickness is not a pressure rating, and unsupported tubular forms are marked “subject to technical review”.
What information is needed for a quotation?
Provide the grade, product form and route (wrought / cast / deposit), dimensions and tolerances, quantity, condition, the exact specification and edition, service environment or temperature, required testing, traceability and certificate type (EN 10204 3.1 or 3.2), finish and delivery location. Availability and the accepted specification route are confirmed with the quotation.
Pipes & TubesSeamless, welded, ERW, EFW, LSAW and SSAW options for industrial piping projects.View pipes
Pipe FittingsButtweld, forged, outlet and special fittings for BOQ and line-list requirements.View fittings
Flanges & FastenersPressure-rated flanges, studs, bolts, nuts and washers with documentation support.View flanges
Material FamiliesStainless steel, carbon steel, alloy steel, duplex, titanium and high nickel alloys.View materials
Engineering SolutionsHVAC, cleanroom, fire safety, laser cutting and fabrication support for projects.View solutions
A controlled path from requirement to delivery support
A technical RFQ flow built for engineers, QA teams and project buyers who need clear standards, traceability and dispatch documentation.
Requirement Submission
Share product, grade, size, class, quantity, drawing and delivery location.
Technical Review
Review standards, specifications, missing inputs and service conditions.
Material Selection
Align stainless, carbon, alloy, duplex, titanium or nickel alloy grades.
Quotation & Approval
Confirm commercial scope, documents, inspection needs and timelines.
Production / Sourcing
Coordinate manufacturing, stock sourcing or fabrication as per scope.
Quality Inspection
Manage dimensional checks, MTC review, PMI or third-party inspection.
Dispatch & Documentation
Prepare packing, tagging, test certificates and dispatch documents.
Delivery Support
Support delivery coordination, document handover and project closure.
Find the right product path
Choose what you need and jump directly to the correct product, material or engineering section.
304/L, 316/L, 321, 347 and 904L for corrosion-resistant piping, fittings, flanges and fabrication.
View stainless steelASTM A106, A53, A105, API 5L and IS 2062 for pressure, utility and structural supply.
View carbon steelUNS S31803, S32205, S32750 and S32760 for chloride, offshore and desalination service.
View duplex gradesInconel, Monel, Hastelloy, Incoloy and Nickel 200/201 for severe corrosion and heat service.
View nickel alloys