1.4980 Forgings X6NiCrTiMoVB25-15-2 · UNS S66286 · A286 · Alloy 660

01What is 1.4980 / X6NiCrTiMoVB25-15-2?

1.4980 is the European material number for an iron-nickel-chromium, austenitic, precipitation-hardening superalloy. Its full EN chemical name is X6NiCrTiMoVB25-15-2, which reads as approximately 0.06 % carbon, 25 % nickel, 15 % chromium and 2 % titanium, with additions of molybdenum, vanadium and boron and iron making up the balance at about 52 to 53 %.

The alloy strengthens by ageing rather than by cold work or martensite formation. During a 16-hour hold at 720 °C, titanium and aluminium combine with nickel to precipitate a coherent, ordered γ′ Ni₃(Ti,Al) phase about 20 to 30 nm across throughout the austenitic matrix. Dislocations have to cut through these particles rather than glide past them, which raises tensile strength to roughly 1,000 MPa and preserves a useful fraction of that strength at temperatures where conventional stainless grades have softened.

Standard austenitic grades such as 304 and 316 lose most of their useful design strength above about 550 °C. Martensitic precipitation-hardening stainless steels such as 17-4 PH and PH 13-8 Mo are stronger at room temperature but are limited to about 315 °C. Nickel-based superalloys such as Inconel 625 operate far higher but cost several times more. 1.4980 covers the range between them: it is serviceable to about 700 °C at roughly a third of the cost of a nickel-based alloy, and it has held that position in turbine fastener and mid-temperature structural applications since the 1950s.

Two further properties affect material selection. 1.4980 is fully austenitic and stays non-magnetic in every condition, including after cold work, which separates it from the martensitic PH stainless grades. It also retains good ductility and toughness at cryogenic temperature, so the same alloy is used in liquid hydrogen and liquid oxygen service as well as in hot turbine sections.

021.4980 equivalents: A286, SUH 660 and Alloy 660

1.4980, A286, UNS S66286, Alloy 660, ASTM A638 Type 660 and JIS SUH 660 all describe one alloy. The main alloying elements were harmonised by international agreement, so a forging produced to any one of these callouts will satisfy the others with negligible exception. The standards differ in trace-element control, where 1.4980 is the strictest of the three families: it carries the tightest sulphur limit at 0.015 % maximum and it is the only one that specifies a minimum boron content.

Ordering note. Because the standards differ in trace elements, write the specific standard and revision on the drawing rather than relying on an equivalence table. Jiangyin Jiangnan Metal Co., Ltd. accepts orders under any callout above and issues cross-certification against a second designation when the supply chain requires it.

Where 1.4980 is stricter than A286

The practical consequence is that European 1.4980 releases run reliably higher in boron than AMS or JIS material, which improves grain-boundary creep resistance at some cost in forgeability. When cross-certifying AMS 5732 material against a 1.4980 callout, specify boron at the upper end of the AMS range so that one heat satisfies both.

03Which European standards govern 1.4980?

Two EN standards carry the alloy. EN 10269 covers fastener and bar stock with specified elevated or low temperature properties. EN 10302 covers creep-resisting steels, nickel and cobalt alloys. German pressure-equipment scope adds VdTÜV-Werkstoffblatt 435 and the AD 2000 Merkblätter. Sour service adds NACE MR0175 and ISO 15156.

Standards are revised periodically. Verify the current revision applicable to your purchase order and state that revision on the drawing, since acceptance criteria have changed between editions.

041.4980 chemical composition

The chemical composition of 1.4980 / X6NiCrTiMoVB25-15-2 per EN 10269 is carbon 0.03 to 0.08 %, silicon 1.00 % max, manganese 2.00 % max, phosphorus 0.025 % max, sulphur 0.015 % max, chromium 13.5 to 16.0 %, nickel 24.0 to 27.0 %, molybdenum 1.00 to 1.50 %, titanium 1.90 to 2.30 %, aluminium 0.35 % max, vanadium 0.10 to 0.50 % and boron 0.0030 to 0.010 %, with iron as balance.

051.4980 mechanical properties in the +AT+P condition

For 1.4980 supplied solution annealed and precipitation hardened (+AT+P) in diameters up to 160 mm, EN 10269 requires a minimum 0.2 % proof strength of 600 MPa, a tensile strength of 900 to 1150 MPa, minimum elongation of 15 % and minimum ISO-V impact energy of 50 J at room temperature.

Section size. The values above are the EN 10269 table for diameters up to 160 mm. Heavier sections and components supplied under EN 10302 or VdTÜV 435 carry different acceptance values, because the quench rate at the core of a thick forging is slower. If your part exceeds 160 mm in ruling section, ask us to confirm the applicable acceptance table before finalising the drawing. This is the most common source of disagreement at material release.

061.4980 strength at elevated temperature

EN 10269 tabulates the minimum 0.2 % proof strength from 100 °C to 700 °C for +AT+P material. It falls from 592 MPa at 100 °C to 380 MPa at 700 °C. At the top of that range 1.4980 still carries more proof strength than annealed 316L carries at room temperature.

Values taken from the EN 10269 elevated-temperature table for 1.4980 in the +AT+P condition. Confirm against the revision of EN 10269 cited on your purchase order before using these figures in a stress-allowable calculation.

071.4980 physical properties

Two of these figures affect production planning. Thermal conductivity of 12.5 W/(m·K) is about a quarter that of carbon steel, so heavy 1.4980 sections need longer soak times to reach temperature uniformly. Under-soaking a thick disc is a common cause of a failed core tensile test. The expansion coefficient of 16.5 ×10⁻⁶/K is higher than most ferritic bolting materials, which matters when 1.4980 fasteners clamp a ferritic flange through a thermal cycle. The joint will relax on heat-up unless the designer accounts for the differential.

081.4980 heat treatment: the +AT+P cycle

1.4980 is supplied in the +AT+P condition: solution annealed at 900 to 980 °C for one to two hours and oil quenched, then precipitation hardened at 720 °C for 16 hours and air cooled. Every mechanical value on this page depends on that cycle being run correctly, particularly the transfer from solution furnace to quench tank, which has to be completed in under about 30 seconds.

Stage 1: solution annealing at 900 to 980 °C

The solution treatment dissolves existing precipitates and returns titanium and aluminium to supersaturated solution, ready to be precipitated in a controlled way during ageing. Soak time is one hour minimum plus about 30 minutes per 25 mm of ruling section. Because 1.4980 conducts heat poorly, that allowance is required rather than conservative.

The choice of solution temperature affects the result. A higher solution temperature near 980 °C coarsens the grain slightly and gives better creep resistance and high-temperature strength. A lower solution temperature near 900 °C keeps the grain finer and gives better notch ductility and room-temperature toughness. State which end of the range the application requires. Where nothing is specified we use 980 °C for rings and discs and 900 °C for fastener stock.

Stage 2: oil quench and transfer time

Stage 3: precipitation hardening at 720 °C for 16 hours

The 16-hour hold is a peak value rather than a rounded figure. Shorter ageing leaves the γ′ precipitates under-developed and the alloy below its proof-strength minimum. Longer ageing over-ages them: at 24 hours the particles have coarsened from about 22 nm to 60 to 80 nm, the size distribution has broadened, and tensile strength falls by around 10 to 12 %. We hold 720 ± 3 °C for 16 h ± 15 min, counted from the point at which the coldest thermocouple in the load reaches 715 °C.

Some specifications call for a two-step age of 16 hours at 720 °C followed by a second hold near 620 °C. Where the drawing requires it, state this at enquiry. It runs in the same furnace cycle but adds to the schedule.

091.4980 forged products supplied

Jiangyin Jiangnan Metal Co., Ltd. produces 1.4980 as open-die and ring-rolled forgings only, not as castings or welded fabrications. Forging breaks down the as-cast dendritic structure and develops grain flow that follows the part contour, which is what delivers the fatigue life the alloy is specified for.

We also produce 1.4980 as forged pipes and forged tubes, forged round bars, forged blocks and blanks, forged gears and gear blanks, forged nozzles, eccentric shafts, extrusion die rings and liners, forged wheels and rolls, and custom near-net-shape forgings to customer drawings.

101.4980 manufacturing capability

1.4980 has a narrow working window on the press. It stays soft at high temperature while incipient γ′ begins forming below 980 °C, so reheats are frequent. These are the envelopes held for this grade.

Max ring OD

1,800mm, seamless rolled

Max disc ∅

1,500mm

Max shaft length

6metres

Max piece weight

5,000kg

Bar diameter

25–400mm round or hex

Min forge ratio

4:16:1 for bar stock

Forging window

1.4980 is forged between 1,175 °C and 1,010 °C. Above 1,175 °C there is a risk of incipient melting at the grain boundaries. Below about 1,010 °C the alloy work-hardens fast enough to tear at the surface. In production we pre-heat to 1,150 °C, soak for 60 minutes plus 1.5 minutes per millimetre of section, and take two or three reheats at 1,120 °C through the sequence, without letting the piece fall below 950 °C while under the hammer.

The 4:1 minimum reduction applies to all disc work. Below it the as-cast dendritic structure is not fully broken down and shows as banding on the final macro-etch. Every disc forging is macro-etched and inspected for grain flow to ASTM E381 before dispatch. Parts that fail that inspection are not shipped, regardless of tensile results.

Melting route

Two routes are available for 1.4980 and the choice belongs to the buyer.

• VIM single melt. Vacuum induction melted, with working vacuum below 1 × 10⁻³ mbar before titanium and aluminium are charged. Suitable for most European industrial, pressure-equipment and valve applications.
• VIM-VAR double melt. Vacuum induction melting followed by vacuum arc remelting. Used where inclusion clusters above about 50 µm would initiate low-cycle fatigue cracks: critical rotating parts, turbine discs, flight-safety fastener stock. Adds cost and about four weeks to the schedule.

Every heat is sampled three times by optical emission spectrometry at pre-tap, mid-pour and top-of-ingot. The finished part is re-checked by OES against the melt analysis, with a permitted delta of 0.02 %.

11Certification, testing and inspection

Every 1.4980 forging shipped by Jiangyin Jiangnan Metal Co., Ltd. carries an EN 10204 3.1 mill certificate covering melt chemistry, mechanical test results, heat-treatment record, dimensional report and single-heat traceability. EN 10204 3.2 third-party witnessed certification is available on request through a client-nominated inspection body.

12Welding, machining and fabrication of 1.4980

Can 1.4980 be welded?

Yes, by GTAW, GMAW, electron-beam and laser processes with a matching filler. The sequence matters more than the process. Weld in the solution-annealed condition rather than the aged condition, then solution treat and age the completed assembly for full-strength service.

The controlling risk is strain-age cracking. In a highly restrained joint the γ′ precipitation reaction during a post-weld thermal cycle happens at the same time as residual stress relaxation, and the two combine to crack grain boundaries, particularly boundaries already weakened by η-phase from an earlier slow quench. Controlled heating and cooling rates through the 600 to 800 °C window are required. Preheat is not normally needed. A post-weld stress relief near 870 °C is recommended for restrained joints.

Machining 1.4980

In the aged condition 1.4980 machines at roughly 30 to 40 % of the rate of Type 304, since it is both strong and rapidly work-hardening. Practices that work:

• Rigid setups with minimum overhang. Deflection causes rubbing, and rubbing work-hardens the surface.
• Sharp, positive-rake carbide tooling, replaced on a schedule rather than on failure
• Heavy positive feeds at low to moderate speed, roughly 25 to 40 m/min for turning
• Generous flood coolant directed at the cutting edge
• No dwelling. A tool that stops in the cut work-hardens the surface beneath it, and the next pass has to cut through that layer.

Where machining content is heavy, order in the +AT condition, machine soft, and age afterwards. See the note in the mechanical properties section above.

Hot working and forming

Hot work between 1,175 °C and 1,010 °C, cool slowly from forging temperature, then solution treat and age. Heavy sections may need an intermediate solution treatment between forging operations to restore workability. Cold forming is practical only in the solution-annealed condition, and the work-hardening rate is high even then.

131.4980 compared with other forging alloys

Selecting 1.4980 is generally a cost against temperature decision. It is not the strongest alloy available. It is the one that holds acceptable strength to 700 °C at a price that nickel-based superalloys do not reach.

Relative cost is indicative and moves with nickel, cobalt and molybdenum pricing. Request a current quotation rather than budgeting from a ratio.

14Where 1.4980 forgings are used

The common requirement across these applications is a part that has to carry mechanical load at a temperature where ordinary stainless steel has softened, without paying nickel-superalloy prices.

• High-temperature bolting and fasteners. The original and still the dominant use. EN 10269 exists largely for this: turbine casing bolts, manifold studs, exhaust fasteners and engine components under combined heat and stress.
• Gas turbine compressor discs and rings for aero-derivative and industrial gas turbines where service stays below 700 °C and Inconel 718 cost is not justified by the duty.
• Steam turbine components. Valve stems, spindles, blade roots and fasteners in the hot end of steam plant, under AD 2000 and TRD scope.
• Pressure equipment. Forged flanges, tube sheets, sleeves and shell components for shell-and-tube heat exchangers, air receivers and pressure vessels under PED 2014/68/EU.
• Offshore and subsea oil and gas. Wellhead and Christmas-tree components, tubing hangers, completion tools and subsea production equipment, with NACE MR0175 / ISO 15156 scope for sour service.
• Valves. Bodies, seat rings, stems, plugs and blocks for ball, gate, globe, check and plug valves in high-temperature process duty.
• Industrial furnaces and heat-treating equipment. Structural components, rolls, fixtures and hangers operating continuously in the 600 to 700 °C range.
• Cryogenic service. The alloy retains toughness down to liquid hydrogen and liquid oxygen temperatures, so it is used in cryogenic structural fittings and turbopump components.
• Power transmission. Gears, spindles, shafts and gearbox components in hot-running compressor and turbine trains.
• Extrusion tooling. Die rings and container liners for hot aluminium and copper extrusion presses.

15How to specify a 1.4980 forging order

The following seven items are what we need to quote. They are also the seven points at which 1.4980 orders most often go wrong.

1. Designation and governing standard

   State the grade as 1.4980 / X6NiCrTiMoVB25-15-2 and name the standard and its revision: EN 10269 for fastener and bar stock, EN 10302 for creep-resistant structural service, VdTÜV-Werkstoffblatt 435 for German pressure-equipment scope. If you are working from a legacy drawing marked Z6 NCT 25, HR 1810, BS S151 or X5 NiCrTi 26-15, say so. We will certify to EN 1.4980 and cross-reference the legacy callout on the certificate.

2. Delivery condition

   State +AT+P for solution annealed and precipitation hardened, or +AT for solution annealed only if you will machine or form before ageing. If the application favours creep resistance over notch ductility, request the 980 °C solution temperature explicitly.

3. Melting route

   State AOD, VIM single melt, or VIM-VAR double melt. This is the largest single factor in both price and lead time. VIM-VAR applies to critical rotating parts and fatigue-driven applications. It is over-specification for most valve and pressure-equipment work.

4. Drawing, tolerances and forge ratio

   Send a 2D drawing or 3D model with dimensions, tolerances, machining allowance and surface finish. For discs and rings, state any minimum forge-ratio or grain-flow requirement. We hold 4:1 minimum as standard, though some specifications require more.

5. Non-destructive examination

   Name the ultrasonic acceptance standard and class: EN 10228-3, SEP 1921 or ASTM A388. Add any dye-penetrant, grain-size or macro-etch requirement. If this is left blank we quote EN 10228-3 as default, which may not match your code.

6. Inspection certificate

   State EN 10204 3.1 for a mill certificate, our standard supply, or EN 10204 3.2 for third-party witnessed certification. For 3.2, name the inspection body you want, whether TÜV, DNV, Bureau Veritas, Lloyd's Register or SGS, since scheduling their attendance drives the delivery date.

7. Quantity, Incoterms and destination

   State quantity, required delivery date, Incoterms such as EXW Jiangyin, FOB Shanghai, CIF or DDP, and the destination port or city. If the material is going into a project with a fixed commissioning date, give us the date rather than the lead time, since it affects how we schedule the melt.

16Glossary

1.4980

EN material number for the iron-nickel-chromium precipitation-hardening superalloy X6NiCrTiMoVB25-15-2, the European designation of the alloy known in the United States as A286 or UNS S66286.

X6NiCrTiMoVB25-15-2

The EN chemical name of material 1.4980. Reads as approximately 0.06 % carbon, 25 % nickel, 15 % chromium and 2 % titanium, with molybdenum, vanadium and boron additions.

+AT

EN delivery-condition code for solution annealed. The soft, formable condition at approximately 250 MPa proof strength and 40 % elongation.

+AT+P

Solution annealed followed by precipitation hardened. The standard supply condition for finished 1.4980 forgings and the basis of every mechanical value on this page.

γ′ (gamma prime)

The ordered Ni₃(Ti,Al) precipitate formed during ageing at 720 °C. Coherent with the matrix, approximately 20 to 30 nm across, and the source of the alloy's strength and creep resistance.

η (eta) phase

Hexagonal Ni₃Ti that precipitates on grain boundaries if a solution-treated part cools too slowly through approximately 760 to 700 °C. Embrittles boundaries, reduces fatigue life, and cannot be reversed without re-melting.

Strain-age cracking

Intergranular cracking in γ′-strengthened alloys when a post-weld thermal cycle causes precipitation and stress relaxation simultaneously in a restrained joint.

EN 10269

European standard for steels and nickel alloys for fasteners with specified elevated and low temperature properties. Governs 1.4980 bar and fastener stock.

EN 10302

European standard for creep-resisting steels, nickel and cobalt alloys. Governs 1.4980 for elevated-temperature structural service.

EN 10204 3.1

Inspection certificate issued by the manufacturer's own independent inspection department, with actual test results on the delivered material.

EN 10204 3.2

Inspection certificate countersigned by an independent inspection body or the purchaser's representative, who witnesses the tests.

VIM

Vacuum induction melting. Primary melting under vacuum to control gas content and protect the oxygen-sensitive titanium and boron additions.

VAR

Vacuum arc remelting. Secondary remelt that improves homogeneity and removes inclusion clusters. VIM-VAR double-melted material is standard for critical rotating parts.

Forge ratio

The ratio of starting cross-section to finished cross-section, which measures how thoroughly the as-cast structure has been broken down. We hold 4:1 minimum for discs and 6:1 for bar stock.

Ruling section

The greatest thickness through which the part has to be quenched. It governs the achievable cooling rate at the core and therefore which acceptance table applies.

17Frequently asked questions about 1.4980