What is Alloy 59?
Alloy 59 is a fully austenitic, solid-solution strengthened nickel-chromium-molybdenum alloy used in severe wet-corrosion service. It carries more chromium and more molybdenum together than any other widely available Ni-Cr-Mo grade. That is why it is specified where Hastelloy C-276 reaches its limit in oxidizing conditions, or where Alloy 22 reaches its limit in hot concentrated acids.
The chemistry has two defining features. Chromium is held at 22 to 24 % while molybdenum stays at 15 to 16.5 %, so the material resists oxidizing and reducing media at the same time rather than trading one for the other. Carbon is capped at 0.010 % and silicon at 0.10 %. Those limits prevent carbide and intermetallic precipitation at grain boundaries during hot forging and welding, so an Alloy 59 forging keeps the corrosion resistance of its parent material through the heat-affected zone.
Alloy 59 is not a precipitation-hardening alloy. It is delivered and used in the solution-annealed condition, and no ageing treatment is applied at any stage. This point is often stated incorrectly on material listings and in purchase specifications.
Jiangyin Jiangnan Metal Co., Ltd. forges Alloy 59 into rings, flanges, bars, discs, shafts, sleeves and tube sheets, working from customer drawings or from a plain dimension list. Typical buyers are FGD system builders, chemical plant EPC contractors, valve and pump makers, and heat exchanger fabricators.
Designations and equivalent standards
Alloy 59 appears under several names on drawings and enquiries. They all describe the same chemistry. Only the product standard changes what is tested and certified.
| System | Designation |
|---|---|
| Common name | Alloy 59, Nickel Alloy 59 |
| UNS | N06059 |
| Werkstoff (W.Nr.) | 2.4605 |
| EN chemical | NiCr23Mo16Al |
| Producer trade names | Nicrofer 5923 hMo, VDM Alloy 59, BOEHLER L059, Haynes 59 |
| Welding filler | ERNiCrMo-13, S Ni 6059, W.Nr. 2.4609 |
| ASME Sec. IX | P-No. 43 |
| Standard | Scope |
|---|---|
| ASTM B564 / ASME SB-564 | Nickel alloy forgings. The primary standard for forged rings, discs, shafts and blanks |
| ASTM B462 / ASME SB-462 | Forged or rolled pipe flanges, fittings, valves and parts for corrosive high-temperature service |
| ASTM B574 | Rod, bar and wire |
| ASTM B575 | Plate, sheet and strip. Reference chemistry |
| DIN 17744 | Nickel wrought alloys with molybdenum and chromium. Chemistry and properties |
| DIN 17752 | Nickel and nickel alloy bar |
| VdTUV Werkstoffblatt 505 | German pressure-equipment approval, including elevated-temperature minima |
| NACE MR0175 / ISO 15156-3 | Sour service qualification for oil and gas |
| ASME B16.5 / B16.47 / EN 1092-1 | Dimensional standards when the forging is a flange |
State the product standard on the purchase order. The name Alloy 59 defines chemistry but not the test regime.
Chemical composition of Alloy 59
Composition limits in weight percent, per ASTM B564 and B575 and DIN 17744.
| Element | Symbol | Min | Max |
|---|---|---|---|
| Nickel | Ni | 59.0 | Balance |
| Chromium | Cr | 22.0 | 24.0 |
| Molybdenum | Mo | 15.0 | 16.5 |
| Aluminium | Al | 0.10 | 0.40 |
| Iron | Fe | – | 1.50 |
| Copper | Cu | – | 0.50 |
| Manganese | Mn | – | 0.50 |
| Cobalt | Co | – | 0.30 |
| Silicon | Si | – | 0.10 |
| Phosphorus | P | – | 0.015 |
| Sulfur | S | – | 0.010 |
| Carbon | C | – | 0.010 |
P and S limits shown are the ASTM values. DIN 17744 permits P up to 0.025 % and S up to 0.015 %. Tighter limits can be agreed at enquiry.
Why the carbon limit matters
At C of 0.010 % maximum and Si of 0.10 % maximum, Alloy 59 has no tendency to form grain-boundary precipitates during hot forging or welding. A heavy forged section can therefore leave the press, be solution annealed once, and still pass an ASTM G28 Method A test.
Mechanical properties
Minimum room-temperature values in the solution-annealed condition. Actual results on our forgings are reported on the mill certificate for each heat and each heat-treatment lot.
| Property | Value | Unit |
|---|---|---|
| Tensile strength, Rm | 690 min | MPa (100 ksi) |
| Yield strength, Rp0.2, DIN 17744 | 340 min | MPa |
| Yield strength, Rp0.2, ASTM B564 | 310 min | MPa (45 ksi) |
| Elongation, A5 | 40 min | % |
| Hardness | 100 max | HRB, typically 85 to 95 |
| Modulus of elasticity | 210 | GPa |
| Impact toughness, KV at 20 °C | 150 typ. | J |
Heavy sections above roughly 100 mm may be agreed at reduced minima. State the ruling section at enquiry.
Physical properties
| Property | Value | Unit |
|---|---|---|
| Density | 8.6 | g/cm³ (0.311 lb/in³) |
| Melting range | 1310 to 1360 | °C |
| Thermal conductivity | 10.4 | W/(m·K) |
| Specific heat capacity | 414 | J/(kg·K) |
| Electrical resistivity | 1.26 | Ω·mm²/m |
| Coefficient of thermal expansion, 20 to 100 °C | 12.6 | 10-6/K |
| Crystal structure | FCC, fully austenitic | – |
| Magnetic response | Non-magnetic | – |
Low thermal conductivity and a high work-hardening rate govern how Alloy 59 must be forged and machined. See the forging and machining sections below.
Corrosion resistance
With a PREN of about 75, calculated as Cr plus 3.3 times Mo at a typical 23 % Cr and 15.8 % Mo, Alloy 59 sits at the top of the commercially available nickel-chromium-molybdenum range.
Where it performs
- Oxidizing and reducing media at the same time. The high-Cr and high-Mo balance removes the usual compromise between C-276 and high-chromium grades.
- Chloride pitting and crevice corrosion. Critical pitting and crevice temperatures in ASTM G48 testing are among the highest of any wrought Ni-Cr-Mo alloy.
- Chloride stress corrosion cracking, under conditions that crack austenitic stainless steels.
- Mineral acids, including sulfuric, hydrochloric, nitric, phosphoric and hydrofluoric acid, and particularly sulfuric and hydrochloric mixtures.
- Sour service, qualified to NACE MR0175 / ISO 15156-3.
- Weld and heat-affected zone. No sensitisation, so a welded assembly behaves like the parent forging.
Where it is not the right choice
Alloy 59 is a wet-corrosion alloy rather than a creep-resistant high-temperature alloy. For sustained service above roughly 500 to 550 °C where creep strength governs, Inconel 617, Inconel 625 or Alloy 602 CA are the appropriate materials. It is also not a low-cost option. Where the medium is only mildly aggressive, 6Mo super-austenitic stainless or duplex will do the same job for a fraction of the price, and we will say so at enquiry stage.
How we forge Alloy 59
Alloy 59 has a narrow hot-working window and a steep work-hardening rate. The sequence below is the route we run at Jiangyin Jiangnan Metal for every Alloy 59 order, from ingot to packed forging.
-
Melting
EAF and VOD refining, with ESR remelting where the specification or section size requires it. This holds C to
0.010 % maxand Si to0.10 % max. -
Heating and upsetting
Soak, then upset. Hot working runs
1180 to 950 °C. Work stops before the piece drops under 950 °C and the piece is reheated. -
Open-die forging or ring rolling
Drawing, punching and radial-axial ring rolling to shape, with a controlled forging ratio to break down the cast structure and refine grain size.
-
Solution annealing
1100 to 1180 °C, preferably 1120 °C, then water quench or cool faster than150 °C/mindown to 500 °C. No ageing treatment is applied. -
Rough machining
Descale and rough machine to your drawing allowance, or supply as-forged with a stated envelope if you machine in-house.
-
Testing
Chemistry, tensile, hardness and UT to
EN 10228-3,SEP 1921orASTM A388, plus optionalASTM G28-Aand PMI. -
Certification and dispatch
EN 10204 3.1mill certificate, or3.2with third-party witness. Marking, preservation and export packing follow.
A common specification error on Alloy 59 orders
Purchase orders that call for solution treatment plus ageing, copied across from Inconel 718 or 17-4PH practice. Alloy 59 takes its strength from chromium and molybdenum held in solid solution. Ageing it would precipitate intermetallic phases at grain boundaries and remove the corrosion resistance the alloy was bought for. If a drawing specifies ageing, we raise it before starting.
Alloy 59 product forms and size range
All items are made to order against a drawing or dimension list. Single pieces are accepted, including one-off replacement parts and prototypes.
| Product form | Indicative size range | Typical use |
|---|---|---|
| Seamless rolled rings | OD 200 to 3000 mm, wall 30 to 400 mm, height 40 to 800 mm | Scrubber shells, vessel courses, bearing seats |
| Forged rings | OD 100 to 2000 mm, any wall | Retaining rings, spacers, seal rings |
| Forged flanges | DN 15 to DN 1600, ASME B16.5 / B16.47 / EN 1092-1 | Piping, nozzles, manways |
| Round bars | Dia. 60 to 800 mm, length to 6000 mm | Valve stems, fastener stock, machining stock |
| Discs and blanks | Dia. 100 to 1500 mm, thickness 20 to 500 mm | Blind flanges, valve discs, closure heads |
| Tube sheets | Dia. to 2500 mm, thickness to 300 mm | Shell-and-tube heat exchangers |
| Shafts and spindles | Dia. 80 to 600 mm, length to 6000 mm | Agitators, pumps, fans |
| Sleeves and bushings | OD 80 to 1200 mm | Pump wear parts, liners |
| Hollow forgings and cylinders | OD to 1500 mm, length to 3000 mm | Reactor sections, nozzles |
| Valve bodies and blocks | To drawing | Ball, gate, globe, check and plug valves |
Single-piece weight from a few kilograms up to approximately 3000 kg. Sizes outside this envelope are often still possible.
Delivery conditions offered
- As-forged, solution annealed, with a stated machining allowance
- Rough machined to your drawing. Recommended for heavy sections, since it reduces freight and lets UT reach a clean surface
- Finish machined to final dimensions and surface finish
- Machined and pressure tested, for valve and flange assemblies
Machining and welding Alloy 59
Machining
Alloy 59 work hardens rapidly and conducts heat poorly, so a technique that works on stainless steel will glaze the surface and destroy tool life. The working rules:
- Rigid setup, minimum overhang, sharp positive-rake carbide inserts. Replace on wear rather than on breakage.
- Low speed and heavy feed. Indicative turning: vc 15 to 25 m/min roughing, 25 to 40 m/min finishing, f 0.15 to 0.30 mm/rev.
- Depth of cut deep enough to get under the previous pass work-hardened layer, typically 1.5 mm or more. No dwelling or rubbing.
- Flood coolant at high concentration, directed at the cutting edge.
- Climb mill where the machine allows it, and avoid interrupted light cuts.
Welding
- Matching filler: ERNiCrMo-13, S Ni 6059, W.Nr. 2.4609. Alloy 59 filler is also used to weld other Ni-Cr-Mo alloys and to overlay carbon steel.
- ASME Section IX P-No. 43. GTAW, GMAW, SMAW and plasma are all suitable.
- Weld in the solution-annealed condition, on clean, degreased, scale-free surfaces.
- No preheat. Keep interpass temperature low and heat input moderate, and use stringer beads.
- Because C and Si are held low, the heat-affected zone does not sensitise, and post-weld solution annealing is not required for most wet-corrosion service.
- Good thermal stability and low hot-cracking sensitivity. Weld metal corrosion resistance matches the parent forging.
Testing, NDT and certification
What ships with the forging. Specify the level you need on the purchase order and it is priced in from the start rather than added later.
| Test | Standard | Status |
|---|---|---|
| Chemical analysis, heat and product | ASTM E1473, spectrometry | Standard |
| Tensile test, room temperature | ASTM A370, EN ISO 6892-1 | Standard |
| Hardness | ASTM E18 (HRB) | Standard |
| Ultrasonic testing | EN 10228-3, SEP 1921, ASTM A388 | Standard |
| Liquid penetrant testing | ASTM E165, EN ISO 3452 | On request |
| Intergranular corrosion | ASTM G28 Method A | On request |
| Pitting and crevice corrosion | ASTM G48 Method C / E | On request |
| Impact test, Charpy V | EN ISO 148-1, ASTM E23 | On request |
| Grain size | ASTM E112 | On request |
| Positive material identification | PMI, XRF or OES | On request |
| Sour service qualification | NACE MR0175 / ISO 15156-3 | On request |
| Mill certificate | EN 10204 3.1 | Standard |
| Third-party witnessed certificate | EN 10204 3.2, TUV, SGS, BV, Lloyd's | On request |
Where Alloy 59 forgings are used
Flue gas desulfurization and waste incineration
The application the alloy was developed for. Scrubber shells and rolled rings, duct and damper components, fan and agitator shafts, spray header nozzles, and quench-zone parts in coal-fired power stations and municipal waste incinerators. Also SO2 scrubbers on marine diesel engines.
Chemical and petrochemical processing
Reactor sections, forged flanges and nozzles, tube sheets and heat exchanger parts for acetic acid and acetic anhydride, hydrofluoric acid, sulfuric acid coolers, and organic processes running chloride-based catalyst systems. This last case is where Alloy 59 most clearly outperforms C-276.
Oil, gas and geothermal
Sour-service valve bodies, stems, seat rings and blocks, subsea and wellhead components, Christmas tree parts, and geothermal wellhead and tubing hardware. Qualified to NACE MR0175 / ISO 15156-3.
Pulp, paper and pharmaceutical
Bleaching plant equipment handling chlorine dioxide and chloride-bearing liquors, digester and washer hardware, and reactor and vessel components for pharmaceutical and fine-chemical duty where product purity forbids iron pickup.
Pollution control and environmental engineering
Wet scrubbers, absorber internals, seawater and brine handling equipment, and acid gas cleaning systems.
Alloy 59 compared with Alloy 22, C-276 and 625
The four grades an engineer usually shortlists together. Nominal chemistry in wt.%. PREN calculated as Cr plus 3.3 times Mo plus 1.65 times W, at mid-range composition.
| Property | Alloy 59 N06059 |
Alloy 22 N06022 |
C-276 N10276 |
Alloy 625 N06625 |
|---|---|---|---|---|
| Chromium | 22.0 to 24.0 | 20.0 to 22.5 | 14.5 to 16.5 | 20.0 to 23.0 |
| Molybdenum | 15.0 to 16.5 | 12.5 to 14.5 | 15.0 to 17.0 | 8.0 to 10.0 |
| Tungsten | – | 2.5 to 3.5 | 3.0 to 4.5 | – |
| Iron, max | 1.5 | 2.0 to 6.0 | 4.0 to 7.0 | 5.0 |
| Carbon, max | 0.010 | 0.015 | 0.010 | 0.10 |
| PREN, approx. | 75 | 71 | 74 | 51 |
| Oxidizing media | Very high | High | Moderate | Moderate to high |
| Reducing media | Very high | High | Very high | Moderate |
| HAZ stability | Very high | High | Moderate to high | Moderate to high |
| Strengthening | Solid solution | Solid solution | Solid solution | Solid solution, Nb-bearing |
| Relative cost | Highest | High | High | Moderate |
How to choose
If the medium alternates between oxidizing and reducing, or contains both chloride and an oxidizing acid, Alloy 59 is the safer specification and its higher chromium is the deciding factor over C-276. If the service is purely reducing, hydrochloric acid for example, C-276 will usually do the job at lower cost. Alloy 22 sits between them. Alloy 625 answers a different question: it is chosen for strength and elevated-temperature service rather than for the most severe wet corrosion.
How to order Alloy 59 forgings
Six pieces of information turn an enquiry into a firm price. Send them to sales@steelforgepieces.com and we normally reply within one working day.
| No. | Item | Example |
|---|---|---|
| 1 | Drawing, or dimensions with tolerance | Ring OD 1200 x ID 900 x H 250 mm |
| 2 | Quantity | 4 pcs, plus 2 pcs option |
| 3 | Product standard | ASTM B564 UNS N06059 |
| 4 | Delivery condition | Solution annealed, rough machined, 5 mm allowance |
| 5 | Testing required | UT to EN 10228-3 class 3, ASTM G28-A |
| 6 | Certification level | EN 10204 3.1, or 3.2 with TUV witness |
A sketch with three dimensions and the duty is enough for a budget figure if no drawing is available.
Frequently asked questions
What is Alloy 59 (UNS N06059)?
Alloy 59, also designated UNS N06059, W.Nr. 2.4605 and NiCr23Mo16Al, is a nickel-chromium-molybdenum alloy containing 22 to 24 % chromium, 15 to 16.5 % molybdenum and a balance of nickel at 59 % minimum, with carbon held to 0.010 % maximum and silicon to 0.10 % maximum. Its PREN of about 75 is the highest among commercial Ni-Cr-Mo alloys, giving high resistance to corrosion in both oxidizing and reducing media.
What is the chemical composition of Alloy 59?
Alloy 59 (UNS N06059 / 2.4605) contains 22.0 to 24.0 % chromium, 15.0 to 16.5 % molybdenum and 0.10 to 0.40 % aluminium, with nickel as the balance at 59 % minimum. Impurity limits are carbon 0.010 % max, silicon 0.10 % max, iron 1.50 % max, cobalt 0.30 % max, copper 0.50 % max, manganese 0.50 % max, phosphorus 0.015 % max and sulfur 0.010 % max per ASTM. DIN 17744 permits phosphorus up to 0.025 % and sulfur up to 0.015 %.
What are the mechanical and physical properties of Alloy 59?
In the solution-annealed condition at 20 °C, Alloy 59 has a minimum tensile strength of 690 MPa (100 ksi), a minimum 0.2 % proof strength of 340 MPa per DIN 17744 or 310 MPa (45 ksi) per ASTM B564, minimum elongation of 40 %, hardness of 100 HRB max and a modulus of elasticity of 210 GPa. Density is 8.6 g/cm³ (0.311 lb/in³), melting range 1310 to 1360 °C, thermal conductivity 10.4 W/(m·K), specific heat 414 J/(kg·K), electrical resistivity 1.26 Ω·mm²/m and coefficient of thermal expansion 12.6 x 10-6/K between 20 and 100 °C. The structure is face-centred cubic, fully austenitic and non-magnetic.
Are Alloy 59, UNS N06059, 2.4605 and NiCr23Mo16Al the same material?
Yes. Alloy 59 is the common industry name, N06059 the UNS number, 2.4605 the German Werkstoff number and NiCr23Mo16Al the EN chemical designation. Nicrofer 5923 hMo is a producer trade name for the same alloy. All describe one chemistry. Only the product standard on the order changes what is tested and certified.
At what temperature is Alloy 59 forged?
Hot working runs from 1180 °C down to 950 °C. Forging must stop and the piece be reheated before it falls below 950 °C, otherwise cracking and an unrecrystallised structure result. Every forging is then solution annealed at 1100 to 1180 °C and water quenched or cooled rapidly.
Does Alloy 59 need age hardening after forging?
No. Alloy 59 is solid-solution strengthened, not precipitation hardening. Its strength comes from chromium and molybdenum held in solution, and the correct final heat treatment is solution annealing at 1100 to 1180 °C followed by rapid cooling. Ageing would precipitate intermetallic phases at grain boundaries and reduce the corrosion resistance the alloy is bought for, so it is not applied.
What is the difference between Alloy 59, Alloy 22 and Hastelloy C-276?
Alloy 59 carries the highest combined chromium and molybdenum: 22 to 24 % Cr with 15 to 16.5 % Mo, against 20 to 22.5 % Cr with 12.5 to 14.5 % Mo for Alloy 22, and 14.5 to 16.5 % Cr with 15 to 17 % Mo for C-276. The higher chromium makes Alloy 59 better in oxidizing acids than C-276, and its tungsten-free, low-carbon, low-silicon chemistry gives better heat-affected-zone stability. PREN is about 75 for Alloy 59, roughly 71 for Alloy 22 and 74 for C-276.
Which standards cover Alloy 59 forgings?
ASTM B564 / ASME SB-564 for nickel alloy forgings, ASTM B462 / ASME SB-462 for forged flanges, fittings and valve parts, and ASTM B574 for rod and bar. European practice uses DIN 17744, DIN 17752 and VdTUV Werkstoffblatt 505. Sour service is qualified to NACE MR0175 / ISO 15156-3.
What is the PREN of Alloy 59?
Using PREN equal to Cr plus 3.3 times Mo, a typical 23 % Cr and 15.8 % Mo gives approximately 75. This is the highest of any commercially produced nickel-chromium-molybdenum alloy, and the reason it resists chloride pitting and crevice corrosion in FGD and seawater service.
Which filler metal is used to weld Alloy 59?
The matching filler is ERNiCrMo-13, also designated S Ni 6059 and W.Nr. 2.4609. Alloy 59 is P-No. 43 under ASME Section IX. Weld in the solution-annealed condition, use no preheat, keep interpass temperature low, and use stringer beads. Because carbon and silicon are held low, the heat-affected zone does not sensitise and post-weld solution annealing is not required for most wet-corrosion service.
Who supplies Alloy 59 forged rings, flanges and bars?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. We manufacture Alloy 59 (UNS N06059) forged rings, seamless rolled rings, flanges, round bars, discs, shafts, sleeves, bushings and tube sheets to customer drawings, supplied solution annealed with EN 10204 3.1 or 3.2 certification. Enquiries: sales@steelforgepieces.com or +86-189-2135-9659.
What is the minimum order quantity for Alloy 59 forgings?
Alloy 59 forgings are made to order and single pieces are accepted, including prototypes and one-off replacement parts. Because the alloy is melted in dedicated heats, larger quantities give a better price per kilogram. Send a drawing or size list with the required standard, quantity and certification level for a firm quotation.
What information do you need to quote?
Six items: finished or rough dimensions or a drawing, quantity, product standard such as ASTM B564 or DIN 17744, delivery condition (as-forged, solution annealed, rough machined or finish machined), testing required such as UT to EN 10228-3 or ASTM G28 corrosion testing, and certification level, EN 10204 3.1 or 3.2.
Where is Alloy 59 used?
Flue gas desulfurization scrubbers, ducts, fans and agitators in power and waste-incineration plants; reactors and coolers for sulfuric, hydrochloric, nitric, phosphoric and acetic acid; chloride-containing organic chemical processes; pulp and paper bleaching; geothermal and offshore oil and gas equipment; and marine SO2 scrubbers on ship diesel engines.
The manufacturer
This page is published by the factory that makes the parts, not by a trading intermediary. The route described above is the one we run.
Jiangyin Jiangnan Metal Co., Ltd.
Open-die forging factory, Jiangyin, Jiangsu, China
- Address
- No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- Telephone
- +86-189-2135-9659
- sales@steelforgepieces.com
- Website
- www.steelforgepieces.com
- Materials
- Nickel alloys, stainless steel, tool steel, alloy steel, carbon steel
- Processes
- Open-die forging, radial-axial ring rolling, solution annealing, rough and finish machining
- Certification
- EN 10204 3.1 as standard. EN 10204 3.2 with TUV, SGS, BV or Lloyd's witness on request
- Markets
- Worldwide. Chemical processing, power, oil and gas, valves, pumps, heat exchangers
Cite this page
Jiangyin Jiangnan Metal Co., Ltd. (2026). Alloy 59 Forgings, UNS N06059 / 2.4605 Forged Rings and Flanges. Retrieved from https://www.steelforgepieces.com/Nickel-Alloy/Alloy-59.html
Manufacturer, Jiangyin, Jiangsu, China. sales@steelforgepieces.com, +86-189-2135-9659. Last revised 13 August 2026.
Property data on this page is compiled from ASTM B564, ASTM B462, ASTM B574, ASTM B575, DIN 17744, DIN 17752, VdTUV Werkstoffblatt 505 and published producer datasheets, and is given for guidance. Values for a specific order are those on the mill certificate supplied with the goods. A plain-text version of this page is available at Alloy-59.md.