Last reviewed . Published by Jiangyin Jiangnan Metal Co., Ltd., open-die forging works, Jiangyin, Jiangsu, China
What is 2.4617?
2.4617 is the EN and DIN material number for the nickel-molybdenum alloy NiMo28, better known as Alloy B-2 or by the trade name Hastelloy B-2, and designated UNS N10665 in the USA. Composition is 26 to 30 % molybdenum, nickel as balance, and almost no chromium. That last point is what makes the alloy excellent in hydrochloric acid and useless in anything oxidising.
Strength comes from solid solution. Dissolved molybdenum distorts the nickel lattice and raises strength without any precipitation involved. So the grade has one heat treated condition, solution annealed, and it cannot be age hardened. A number of datasheets in circulation say 2.4617 is solution treated and aged. That text has been copied from a precipitation hardening grade and does not apply here.
2.4617 replaced the original Alloy B. Carbon is held to 0.01 % maximum under DIN 17744 and 0.02 % under ASTM, with silicon and iron restricted as well. Low carbon and silicon stop carbides forming in the weld heat affected zone, which is why fabricated 2.4617 equipment keeps its corrosion resistance as welded. Alloy B did not manage that and suffered knife-line attack alongside welds.
With no chromium there is no passive oxide film. A trace of ferric or cupric ion in a reducing acid is enough to start rapid attack. For mixed or oxidising streams, use a Ni-Cr-Mo grade instead: C-276 (2.4819) or Alloy 59 (2.4605).
Key facts at a glance
| Material number (W.Nr. / EN) | 2.4617 |
|---|---|
| DIN designation | NiMo28 |
| UNS number | N10665 |
| Trade names | Alloy B-2, Hastelloy B-2, Nimofer 6928 |
| Chinese designation | NS3202, formerly NS322 (GB/T 15007) |
| Alloy system | Nickel-molybdenum, solid solution strengthened |
| Nominal composition | Ni bal., Mo 28 %, Fe 2 % max, Cr 1 % max |
| Density | 9.22 g/cm³ (0.333 lb/in³) |
| Melting range | 1330-1380 °C (2426-2516 °F) |
| Heat treated condition | Solution annealed and quenched, not age hardenable |
| Magnetic response | Non-magnetic, so magnetic particle inspection does not apply |
| Melting practice | EAF + VOD or ESR, or VIM + ESR |
| Main service | Hydrochloric, sulphuric, phosphoric and acetic acid, HCl gas |
| Not for | Oxidising media, ferric or cupric chloride, nitric acid, wet chlorine |
Hastelloy is a registered trademark of Haynes International, Inc. Nimofer is a registered trademark of VDM Metals GmbH. We are not connected with either company. The names appear here only to identify the equivalent specification.
2.4617 equivalent grades and standards
The same alloy appears in the trade as 2.4617, UNS N10665, NiMo28, Alloy B-2 and Hastelloy B-2. Order forgings to ASTM B564 or ASME SB-564. Flanges and fittings go to ASTM B462, bar to ASTM B335. The European route is DIN 17744.
| System or country | Designation |
|---|---|
| EN / DIN material number | 2.4617 |
| DIN name | NiMo28 |
| USA, UNS | N10665 |
| USA, trade name | Hastelloy B-2, Alloy B-2 |
| Germany, trade name | Nimofer 6928 |
| ISO | NiMo28 / NW0665 (ISO 6207, 9723, 9724, 9725) |
| China, GB/T 15007 | NS3202, old designation NS322 |
| Welding consumable | ERNiMo-7 (AWS A5.14), ENiMo-7 (AWS A5.11) |
| Standard | Product form covered |
|---|---|
| ASTM B564 / ASME SB-564 | Nickel alloy forgings: rings, flanges, shafts, discs, tube sheets |
| ASTM B462 / ASME SB-462 | Forged or rolled pipe flanges, fittings, valves and parts |
| ASTM B335 / ASME SB-335 | Rod and bar |
| ASTM B333 / ASME SB-333 | Plate, sheet and strip |
| ASTM B366 / ASME SB-366 | Wrought fittings, WPNCB2 |
| ASTM B622 / B619 / B626 | Seamless pipe and tube, welded pipe, welded tube |
| DIN 17744 | Wrought nickel-molybdenum alloys, includes NiMo28 |
| ASME BPVC Section VIII Div. 1 | Lists UNS N10665 for pressure vessel construction |
| ASTM A388 / EN 10228-3 / SEP 1921 | Ultrasonic examination of forgings |
| EN 10204 | Inspection documents: 3.1 works, 3.2 third party witnessed |
Confirm the standard, edition and acceptance class on the purchase order. We supply 2.4617 forgings to any of the above and state the ordered specification on the certificate.
2.4617 chemical composition
Under DIN 17744 the limits are 26.0 to 30.0 % molybdenum, nickel as balance, chromium 1.0 % max, iron 2.0 % max, carbon 0.01 % max and silicon 0.08 % max. Carbon and silicon are held low deliberately. It is what allows the alloy to be used as welded.
| Limit | C | Si | Mn | P | S | Cr | Mo | Ni | Co | Fe | Cu |
|---|---|---|---|---|---|---|---|---|---|---|---|
| min. % | - | - | - | - | - | 0.4 | 26.0 | bal. | - | 1.6 | - |
| max. % | 0.01 | 0.08 | 1.0 | 0.02 | 0.010 | 1.0 | 30.0 | bal. | 1.0 | 2.0 | 0.5 |
ASTM B335 and B564 for UNS N10665 allow slightly wider limits than DIN 17744: carbon 0.02 % max, silicon 0.10 % max, chromium 1.0 % max with no minimum, iron 2.0 % max with no minimum. State on the enquiry which specification governs so the right heat is selected.
2.4617 mechanical properties
ASTM B564 sets these minima for solution annealed forgings: 760 MPa tensile, 350 MPa yield at 0.2 % offset, 40 % elongation. Measured values normally run well above that, around 914 MPa tensile and 396 MPa yield at roughly 168 HB. Buy against the minima, not the typicals.
| Property | Metric | Imperial |
|---|---|---|
| Tensile strength, min. | 760 MPa | 110 000 psi |
| Yield strength 0.2 % offset, min. | 350 MPa | 51 000 psi |
| Elongation in 4D, min. | 40 % | 40 % |
| Property | Metric | Imperial |
|---|---|---|
| Tensile strength | 914 MPa | 133 000 psi |
| Yield strength, 0.2 % offset | 396 MPa | 57 400 psi |
| Elongation at break, in 50.8 mm | 55 % | 55 % |
| Hardness, Brinell | 168 HB | 168 HB |
| Hardness, Rockwell B | 98 HRB | 98 HRB |
| Hardness, Vickers, converted | 241 HV | 241 HV |
| Hardness, Knoop, converted | 186 HK | 186 HK |
Typical figures come from thin annealed product and are for comparison only. A heavy forging behaves differently depending on section size, forging reduction and cooling rate. Acceptance is always against the minima of the ordered specification, on a test piece from the actual heat and heat treatment batch.
2.4617 physical properties
Density 9.22 g/cm³. Melting range 1330 to 1380 °C. Modulus of elasticity about 217 GPa. Thermal conductivity is low, near 11 W/m·K at room temperature, and thermal expansion is on the low side for a nickel alloy. That is why the grade turns up in furnace fixtures as well as acid plant.
| Property | Value | Unit |
|---|---|---|
| Density | 9.22 | g/cm³ |
| Melting range | 1330-1380 | °C |
| Modulus of elasticity | approx. 217 | GPa |
| Specific heat capacity | approx. 373 | J/kg·K |
| Thermal conductivity | approx. 11.1 | W/m·K |
| Mean coefficient of thermal expansion, 20-100 °C | approx. 10.3 | µm/m·K |
| Electrical resistivity | approx. 1.37 | µΩ·m |
| Magnetic permeability | approx. 1.0, non-magnetic | - |
Forging and heat treatment of 2.4617
Forge from about 1180 °C and finish above 900 °C. Solution anneal at 1060 to 1080 °C, then quench in water fast. There is no ageing step. Time spent between roughly 700 and 870 °C precipitates Ni4Mo and Ni3Mo, which embrittles the part and costs corrosion resistance, so the quench rate matters.
How we make 2.4617 forgings
| Stage | What happens |
|---|---|
| 1. Melting | EAF plus VOD followed by ESR remelting, or VIM plus ESR, to reach the low carbon, sulphur and silicon the grade needs and produce a clean ingot without segregation. |
| 2. Ingot preparation | Surface conditioning and a homogenising soak. Nickel-molybdenum alloys are unforgiving about surface defects being forged in. |
| 3. Open-die forging | Upsetting and drawing between flat or swage dies from about 1180 °C, finishing above 900 °C, with reheats as needed. The hot working window is narrower than steel and flow stress is higher. |
| 4. Ring rolling | Punched, mandrel forged, then seamless ring rolled so rings and ring type flanges get continuous circumferential grain flow. |
| 5. Solution annealing | 1060 to 1080 °C, soak time set by section thickness, then rapid water quench to hold molybdenum in solution. |
| 6. Machining | Rough or finish machining to drawing. 2.4617 work hardens fast, so we run positive rake tooling, rigid setups, low speed with heavy positive feed, and plenty of coolant. |
| 7. Inspection | Chemistry, mechanical tests, hardness, dimensions, ultrasonic and penetrant examination, then certification. |
Magnetic particle inspection cannot be used on 2.4617 because the alloy is not magnetic. Surface examination is by liquid penetrant to ASTM E165 or EN ISO 3452-1.
Corrosion resistance of 2.4617
2.4617 handles hydrochloric acid at every concentration up to boiling, plus sulphuric, phosphoric, acetic and formic acid and dry hydrogen chloride gas. It resists chloride stress corrosion cracking too. What it does not handle is oxidisers. Ferric chloride, cupric chloride, nitric acid and wet chlorine all attack it, and traces of any of those in a reducing acid will cause trouble.
Suitable service
- Hydrochloric acid across the full concentration range and up to boiling temperature. This is the main reason the grade exists.
- Sulphuric acid at low to intermediate concentration, and most other non-oxidising mineral acids.
- Phosphoric, acetic and formic acid, and acetic anhydride.
- Dry hydrogen chloride gas at elevated temperature.
- Chloride stress corrosion cracking, well beyond what austenitic stainless steels manage.
- Pitting and crevice corrosion in reducing chloride environments.
- Weld heat affected zones, with no knife-line attack, thanks to the restricted carbon and silicon.
Do not use in
- Oxidising acids and salts: nitric acid, ferric chloride, cupric chloride, oxidising chlorides.
- Reducing acids contaminated with oxidising ions. A small ferric ion content is enough.
- Wet chlorine or hypochlorite.
- Sustained service between about 700 and 870 °C, where intermetallic precipitation embrittles the alloy.
For duty that is part oxidising and part reducing, specify a Ni-Cr-Mo grade: Hastelloy C-276 (2.4819), Hastelloy C-22 (2.4602), Alloy 59 (2.4605) or Hastelloy C-2000. We forge all of them, listed at the foot of this page.
2.4617 forged product forms and size range
We forge 2.4617 to drawing in eleven forms, from small bushings up to large seamless rolled rings. Open-die work needs no dies cut for the part, so a single prototype or spare costs the same to set up as a production batch.
Seamless rolled rings
Ring rolled for continuous circumferential grain flow. Rectangular, contoured and profiled sections.
Forged flanges
Weld neck, slip on, blind, long weld neck, orifice and special flanges to ASME B16.5, B16.47 or drawing.
Shafts and spindles
Stepped, eccentric and hollow shafts, spindles and stems for pumps, agitators and valves.
Discs and blanks
Solid and pierced discs, blanks and hubs, upset forged for radial grain flow.
Bushings and sleeves
Thick wall bushings, sleeves, liners and wear rings, bored and faced.
Tube sheets
Drilled or undrilled tube sheets and baffle plates for shell and tube heat exchangers.
Forged bars
Round, square, flat and stepped bar, forged rather than rolled for heavy sections.
Valve bodies and parts
Valve blocks, bodies, bonnets, seat rings, stems and wedges for severe service valves.
Nozzles and couplings
Set on and set through nozzles, reinforcing pads, couplings and boss forgings.
Forged tubes and pipe
Hollow forged and bored tube, thick wall pipe sections and cylinders.
Custom open-die parts
Any profile from a drawing or a sketch: crankshafts, rolls, wheels, manifolds, crosses.
| Form | Typical range |
|---|---|
| Seamless rolled rings, outside diameter | 150-3000 mm |
| Rings, height and wall | up to 800 mm high, from 25 mm wall |
| Round bar and shafts, diameter | 50-1200 mm |
| Discs, diameter | up to 2500 mm |
| Tube sheets, diameter | up to 3000 mm |
| Single piece weight | 5 kg to 20 000 kg |
| Minimum order | One piece, no tooling cost |
| Supply condition | As forged, rough machined or finish machined |
These ranges are indicative. Send the drawing or the dimensions and we will confirm what is feasible, along with weight, delivery time and price for the actual part.
Applications for 2.4617 forgings
Most 2.4617 forgings end up somewhere hydrochloric or another reducing acid meets a pressure part or a rotating part. The bulk of the demand comes from chemical processing, pharmaceutical and agrochemical plant, acid regeneration, and severe service valves and pumps.
| Industry | Typical 2.4617 forged parts |
|---|---|
| Chemical processing | Reactor flanges and nozzles, agitator shafts, rolled rings for columns and towers, tube sheets for HCl heat exchangers, acid regeneration plant parts |
| Pharmaceutical and fine chemicals | Vessel flanges, agitator shafts and blades, sight glass rings, valve parts in acetic and formic acid duty |
| Severe service valves | Bodies, bonnets, seat rings, stems, wedges, plugs and balls for ball, gate, globe, check and plug valves |
| Pumps and rotating equipment | Chemical pump shafts, plunger pump parts, impeller hubs, wear rings, sleeves and bushings |
| Pressure vessels and heat exchangers | Weld neck and blind flanges, forged shells and cylinders, tube sheets, baffles, forged tube and pipe sections |
| Pollution control and scrubbing | Flue gas desulphurisation parts, scrubber flanges and internals in reducing chloride service |
| Pulp and paper | Bleach plant equipment parts in acidic chloride service |
| Oil, gas and offshore | Wellhead and Christmas tree parts, manifold blocks, subsea parts in sour reducing conditions |
| High temperature equipment | Vacuum furnace fixtures and parts needing a low coefficient of thermal expansion |
2.4617 compared with B-3, C-276 and Alloy 59
Use 2.4617 for straight reducing acid duty. Use 2.4600 (B-3) when the same duty involves thermal cycling or long soaks near 700 to 870 °C. Use C-276 or Alloy 59 when there is any oxidising species in the stream. Chromium content is what decides it.
| Grade | W.Nr. / UNS | Cr % | Mo % | Best for | Avoid in |
|---|---|---|---|---|---|
| Alloy B-2 | 2.4617 / N10665 | 1.0 max | 26-30 | HCl at all concentrations, H2SO4, HCl gas | Any oxidising medium |
| Alloy B-3 | 2.4600 / N10675 | 1.0-3.0 | 27-32 | Same duty as B-2 with far better thermal stability | Any oxidising medium |
| Hastelloy C-276 | 2.4819 / N10276 | 14.5-16.5 | 15-17 | Mixed oxidising and reducing, wet chlorine, seawater | Hot concentrated HCl |
| Alloy 59 | 2.4605 / N06059 | 22-24 | 15-16.5 | The most versatile Ni-Cr-Mo grade, strong acids both ways | Cost sensitive duty |
Where a plant already runs Alloy B-2 and keeps getting embrittlement from thermal cycling, Alloy B-3 (2.4600) is the usual upgrade. It was developed to solve exactly that problem while keeping the same corrosion behaviour.
Testing, inspection and certification
Every 2.4617 forging leaves with an EN 10204 3.1 works certificate. A 3.2 certificate witnessed by TUV, BV, DNV, LR or SGS is available on request. Ultrasonic examination follows EN 10228-3, SEP 1921 or ASTM A388 to the class stated on the order. Surface work is penetrant rather than magnetic particle, since the alloy is not magnetic.
| Test | Method or standard |
|---|---|
| Chemical analysis | Spectrometric analysis of the heat, reported element by element against the ordered specification |
| Tensile test | ASTM A370 or ISO 6892-1: tensile, 0.2 % yield, elongation, reduction of area |
| Hardness | Brinell to ASTM E10 or ISO 6506 |
| Ultrasonic examination | EN 10228-3, SEP 1921 or ASTM A388, class agreed on the order |
| Liquid penetrant examination | ASTM E165 or EN ISO 3452-1, used instead of MPI because 2.4617 is not magnetic |
| Intergranular corrosion test | ASTM G28 method A or B where the order requires it |
| Grain size and microstructure | ASTM E112 on request |
| Dimensional report | Full dimensional inspection report against drawing |
| Positive material identification | Portable XRF on request |
| Certification | EN 10204 3.1 as standard, 3.2 third party witnessed on request |
| Marking | Hard stamped or vibro etched with grade, heat number, part number and inspection stamp |
How to order 2.4617 forgings
Email a drawing or the dimensions to sales@steelforgepieces.com. Quotations normally go out within 24 hours. There is no tooling to pay for, so a single piece is worth asking about.
| Step | What happens |
|---|---|
| 1. Enquiry | Email a drawing, sketch or dimensions to sales@steelforgepieces.com with the quantity and the governing standard, whether that is ASTM B564, DIN 17744 or your own specification. |
| 2. Quotation | We confirm feasibility, forged weight, machining allowance, test scope, lead time and price. Usually within 24 hours. |
| 3. Manufacturing plan | We issue a manufacturing and inspection test plan for approval, with hold and witness points for any third party inspection. |
| 4. Manufacture and test | Melting, forging, solution annealing, machining, then the agreed NDT and mechanical testing. |
| 5. Certify and ship | Certificate issued, parts marked and packed, shipped by sea or air from Shanghai with full export documentation. |
What to put in the enquiry
- Grade: 2.4617 or UNS N10665, plus the governing standard.
- Form and dimensions, or a drawing in PDF, DWG or STEP.
- Quantity, and whether it is a one off or a repeat item.
- Supply condition: as forged, rough machined or finish machined.
- Test and certification requirements, including any third party inspection.
- Delivery destination and the date you need it.
About the works
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging works in Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. We forge rings, flanges, shafts, discs and bar in carbon steel, alloy steel, tool steel, stainless steel and nickel alloys, 2.4617 among them, to customer drawing.
Jiangyin sits in the forging cluster of southern Jiangsu, about 150 km from the Port of Shanghai, which is where most export shipments leave from. Buying from the works rather than a trader means the certificate, the heat number and the inspection plan all come from the shop that actually made the part.
Contact
For a quotation on 2.4617 forgings, send a drawing or the dimensions and we will come back with price, weight and lead time.
- Company
- Jiangyin Jiangnan Metal Co., Ltd.
- Address
- No.1 Chengxiqiao Road, Zhouzhuang Town,
Jiangyin City, Jiangsu Province, China - Phone
- +86 189 2135 9659
- sales@steelforgepieces.com
- Website
- www.steelforgepieces.com
- Business
- Open-die forging works: rings, flanges, shafts, discs, bars
Questions we get asked about 2.4617
What is 2.4617 equivalent to?
UNS N10665, DIN designation NiMo28, and the trade names Alloy B-2, Hastelloy B-2 and Nimofer 6928. In the Chinese GB/T 15007 system it is NS3202, formerly NS322. All of them describe 26 to 30 % molybdenum with nickel as balance.
Is 2.4617 the same as Hastelloy B-2?
Chemically, yes. 2.4617 is the European material number for the composition Haynes International sells under the trademark Hastelloy B-2. Material ordered as 2.4617 or UNS N10665 from another producer meets the same specification. The trademarked name itself may only be used by its owner.
Can 2.4617 be age hardened?
No. It is a solid solution alloy, not a precipitation hardening one. The only heat treatment is solution annealing at 1060 to 1080 degrees C followed by a fast water quench. Holding it between 700 and 870 degrees C does not strengthen it. It precipitates Ni4Mo and Ni3Mo, which embrittles the material and reduces corrosion resistance.
What acids does 2.4617 resist?
Hydrochloric acid at all concentrations and temperatures up to boiling, sulphuric acid at low to intermediate concentration, phosphoric acid, acetic and formic acid, acetic anhydride, and dry hydrogen chloride gas. Oxidising media are a different story: nitric acid, ferric or cupric chloride, wet chlorine and oxidising salts all attack it quickly.
Why does 2.4617 contain almost no chromium?
Chromium builds the passive oxide film that protects stainless steels and Ni-Cr-Mo alloys in oxidising conditions, but that film is not stable in strongly reducing acid. Take the chromium out and rely on 28 % molybdenum instead, and you get the hydrochloric acid resistance 2.4617 is known for. You also give up any use in oxidising service.
What is the difference between 2.4617 (B-2) and 2.4600 (B-3)?
B-3 came about twenty years later, with a small chromium addition and adjusted iron and molybdenum levels for much better thermal stability. Corrosion behaviour in reducing acid is comparable. B-3 tolerates thermal cycling and time at intermediate temperature far better, so it is the normal replacement when a B-2 part has embrittled in service.
Which standard covers 2.4617 forgings?
ASTM B564 and ASME SB-564 cover nickel alloy forgings in UNS N10665. Forged or rolled flanges and fittings fall under ASTM B462, bar under ASTM B335. The German route is DIN 17744. ASME BPVC Section VIII Division 1 lists UNS N10665 for pressure vessel construction.
Can 2.4617 be welded?
Yes, and it is normally left in the as welded condition. The low carbon and silicon stop carbides forming in the heat affected zone, so the weld area keeps its corrosion resistance without a post weld solution anneal. Matching filler is ERNiMo-7 for GTAW and GMAW, ENiMo-7 for SMAW. Keep interpass temperature low and heat input moderate.
Is 2.4617 magnetic?
No, relative permeability sits close to 1.0. That rules out magnetic particle inspection. Surface examination on 2.4617 forgings is done by liquid penetrant to ASTM E165 or EN ISO 3452-1.
How hard is 2.4617 to machine?
It work hardens fast, like most nickel alloys. Rigid setup, sharp positive rake carbide tooling, slow cutting speed with a heavy positive feed so the tool cuts below the work hardened layer, and flood coolant. Do not let the tool dwell or rub. Plenty of customers ask us to rough or finish machine the parts here for that reason.
What is the minimum order quantity for 2.4617 forgings?
One piece. Open-die forging needs no dies cut for the specific part, so there is no tooling charge and a single prototype or spare gets quoted the same way as a batch.
What certification comes with 2.4617 forgings?
An EN 10204 3.1 works certificate as standard, showing heat number, chemical analysis, mechanical test results, heat treatment condition and NDT results. A 3.2 certificate witnessed by a third party such as TUV, BV, DNV, LR or SGS is available on request, with hold and witness points agreed in the manufacturing and inspection test plan.
Document reference
The data on this page is published by the works that makes the parts described. Figures are given for guidance. The specification stated on the purchase order governs the supply.
Jiangyin Jiangnan Metal Co., Ltd. (2026). 2.4617 Forgings: Hastelloy B-2 / UNS N10665 Rolled Rings, Flanges, Shafts and Bars. Jiangyin, Jiangsu, China. https://www.steelforgepieces.com/Nickel-Alloy/2.4617.html
Source: Jiangyin Jiangnan Metal Co., Ltd., open-die forging works, No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. +86 189 2135 9659, sales@steelforgepieces.com. Last reviewed 8 August 2026.