1.4901 material description
1.4901 is the EN material number for X10CrWMoVNb9-2, a 9 % chromium creep-strength-enhanced ferritic (CSEF) steel that is martensitic in the normalized and tempered condition. ASTM and ASME designate the same steel as Grade 92.
The grade was developed from Grade 91 (1.4903 / X10CrMoVNb9-1) by adding 1.5-2.0 % tungsten, reducing molybdenum to 0.3-0.6 % and controlling boron between 0.001 % and 0.006 %. Tungsten and boron stabilise the M23C6 carbides and MX carbonitrides that pin the martensitic lath structure, so the microstructure coarsens more slowly under long-term load at temperature. Creep rupture strength at 600 °C is approximately 25-30 % higher than Grade 91, which allows thinner wall sections in headers and steam piping for the same steam conditions.
1.4901 carries a 1.4xxx EN material number and some databases therefore list it under stainless steels. With 8.5-9.5 % chromium it is a heat-resistant pressure steel selected for creep strength. It has no useful corrosion resistance in wet service and will rust in the same way as a low-alloy steel.
Jiangyin Jiangnan Metal forges 1.4901 as an open-die grade. Individual pieces and small batches are produced to customer drawings rather than held as catalogue stock, which suits the components this steel is normally used for: valve bodies, header stubs, forged tees, rolled rings and thick-wall shells.
Chemical composition of 1.4901
Composition limits for X10CrWMoVNb9-2 in mass percent, balance iron, as specified in EN 10216-2:2014.
| C | Si | Mn | Ni | P | S | Cr | Mo | W | V | N | Nb | Ti | Al | Zr | B |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0.07-0.13 | max 0.50 | 0.30-0.60 | max 0.40 | max 0.020 | max 0.010 | 8.50-9.50 | 0.30-0.60 | 1.50-2.00 | 0.15-0.25 | 0.030-0.070 | 0.04-0.09 | max 0.010 | max 0.020 | max 0.010 | 0.001-0.006 |
Source: EN 10216-2:2014. Product analysis tolerances apply. Each heat is supplied with a certified ladle analysis. Product analysis on the finished forging is available on request.
Function of the alloying elements
- Chromium 8.5-9.5 %. Provides steam-side oxidation resistance and solid-solution strength, and forms the M23C6 carbides on prior-austenite and lath boundaries.
- Tungsten 1.5-2.0 %. The addition that distinguishes Grade 92 from Grade 91. It provides solid-solution strengthening and slows carbide coarsening, which extends creep life.
- Vanadium and niobium. Form fine MX carbonitrides that pin dislocations within the laths.
- Nitrogen 0.03-0.07 %. Combines with vanadium and niobium to form those MX particles.
- Boron 0.001-0.006 %. Segregates to grain boundaries and retards M23C6 coarsening. The permitted range is narrow because higher boron reduces weldability and hot workability.
- Aluminium max 0.02 %. Held low so that nitrogen remains available for MX precipitation rather than being tied up as AlN.
Mechanical properties of 1.4901
Room-temperature properties in the normalized and tempered (+NT) condition. These are the specified minima against which the material is tested and certified. Mill results are normally above them.
| Property | Symbol | Requirement | Unit |
|---|---|---|---|
| Tensile strength | Rm | 620-850 | MPa |
| 0.2 % proof strength | Rp0.2 | min 440 | MPa |
| Elongation at fracture, longitudinal | A | min 19 | % |
| Elongation at fracture, transverse | A | min 17 | % |
| Impact energy at +20 °C, longitudinal | KV | min 40 | J |
| Impact energy at +20 °C, transverse | KV | min 27 | J |
| Hardness after tempering, typical | HBW | max 250 | HBW |
Source: EN 10216-2:2014, condition +NT. ASTM A182 F92 and ASTM A335 P92 specify comparable minima of 620 MPa tensile strength and 440 MPa proof strength. Elevated-temperature proof strength and creep rupture data for a specified temperature and design life are issued with the quotation on request.
Section size. Impact and elongation values on a 600 mm thick forging are lower than those obtained on a 20 mm tube. State the ruling section and the required test location, meaning surface, mid-radius or centre and longitudinal or transverse, at enquiry stage so that the forging ratio and heat-treatment cycle can be planned to suit.
Physical properties of 1.4901
Indicative values for 9Cr-2W steels of this type, suitable for preliminary sizing. Design calculations should use the values given in the governing code.
| Property | Value | Unit |
|---|---|---|
| Density at 20 °C | 7.75-7.85 | g/cm³ |
| Modulus of elasticity at 20 °C | approx. 213 | GPa |
| Modulus of elasticity at 600 °C | approx. 160 | GPa |
| Ac1 transformation temperature | approx. 800-830 | °C |
| Magnetic response | Ferromagnetic | |
| Weldability | Weldable with preheat and mandatory PWHT | |
| ASME Section IX grouping | P-No. 15E |
Indicative literature values for the Grade 92 family.
1.4901 equivalent grades
1.4901 / X10CrWMoVNb9-2 is the European designation for the steel known internationally as Grade 92. The ASTM and ASME designations differ by product form rather than by chemistry.
| Standard or system | Designation | Product form |
|---|---|---|
| EN 10216-2 | X10CrWMoVNb9-2 (1.4901) | Seamless tubes for pressure purposes |
| EN 10222-2 | X10CrWMoVNb9-2 (1.4901) | Forgings for pressure purposes |
| EN 10028-2 | X10CrWMoVNb9-2 (1.4901) | Flat products for pressure purposes |
| ASTM / ASME A182 | F92 / SA-182 F92 | Forged flanges, fittings, valves and parts |
| ASTM / ASME A336 | F92 / SA-336 F92 | Forgings for pressure and high-temperature parts |
| ASTM / ASME A335 | P92 / SA-335 P92 | Seamless ferritic alloy-steel pipe |
| ASTM / ASME A213 | T92 / SA-213 T92 | Seamless boiler, superheater and heat-exchanger tube |
| ASTM A369 | FP92 | Forged and bored pipe |
| ASTM A234 | WP92 | Wrought pipe fittings |
| UNS | K92460 | |
| GB/T 5310 (China) | 10Cr9MoW2VNbBN | Seamless tubes for high-pressure boilers |
| Original development designation | NF616 | |
| Common shorthand | Grade 92, 9Cr-2W, P92, F92, T92 |
Cross-references are given for procurement guidance. Composition and testing requirements are close but not identical in every standard, so the governing specification should be confirmed before one designation is substituted for another.
1.4901 compared with 1.4903: Grade 92 vs Grade 91
Both grades are used for the same types of component and are ordered from the same suppliers. The difference is the tungsten addition.
| Property | 1.4901 / X10CrWMoVNb9-2 | 1.4903 / X10CrMoVNb9-1 |
|---|---|---|
| ASTM grade | Grade 92 (F92 / P92 / T92) | Grade 91 (F91 / P91 / T91) |
| UNS | K92460 | K91560 |
| Tungsten | 1.50-2.00 % | none specified |
| Molybdenum | 0.30-0.60 % | 0.85-1.05 % |
| Boron | 0.001-0.006 % | not specified |
| Tensile strength Rm | min 620 MPa | min 585 MPa |
| Creep rupture strength at 600 °C | approx. 25-30 % higher | reference |
| Relative cost | higher | lower |
| Welding | Narrower parameter window, matching 9Cr-W consumables | Established B9 consumables |
Grade 92 is specified where the additional creep strength is required, for example to reduce wall thickness on a hot reheat line or to hold a design margin at 600 °C that Grade 91 cannot meet. Grade 91 is lower in cost, easier to weld and more widely available. The two grades are not interchangeable. Consumables, welding procedures and code design values all differ, so any substitution requires approval from the design authority.
Heat treatment of 1.4901 forgings
1.4901 is supplied normalized and tempered. Delivered properties depend on this cycle being run correctly for the actual section thickness. Heat treatment is carried out in-house rather than subcontracted.
| Step | Temperature | Cooling | Purpose |
|---|---|---|---|
| Forging | 1150-1220 °C start | Finish above 900 °C | Break down the cast structure and close porosity |
| Dehydrogenation anneal | 650-700 °C | Furnace cool | Heavy sections only, prevents hydrogen flaking |
| Normalizing | 1040-1080 °C | Air or forced air to below 100 °C | Full austenitizing, dissolve carbides, transform to martensite |
| Tempering | 730-780 °C | Air cool | Temper the martensite, precipitate M23C6 and MX, restore toughness |
Cooling after normalizing. The forging must cool below approximately 100 °C before tempering begins. If tempering starts while austenite remains untransformed, that austenite converts to untempered martensite afterwards and impact values will fail.
Tempering temperature. Tempering must remain below Ac1, which is approximately 800-830 °C. If Ac1 is exceeded the part partially re-austenitizes and has to be fully re-normalized and re-tempered.
1.4901 forged product range
All items below are open-die forged to customer drawing in 1.4901 / X10CrWMoVNb9-2, to ASTM, ASME, EN and DIN specifications or to a customer specification.
- BarsRound bars and rods, square and rectangular bars, flat bars, hexagonal bars. Black, rough-turned, peeled or machined.
- Hollow bars and shellsForged hollow bars, sleeves, bushes and bushings, cylinders, barrels, casings, cases, hubs and housings, forged pipe and tube blanks.
- Seamless rolled ringsRing-rolled and open-die forged rings, rectangular and profiled sections.
- Flanges, discs and blocksForged flanges, blocks, discs, disks and forged plates.
- Valve componentsValve bodies, valve bonnets, valve seats, valve seat rings and valve stems.
- Forged fittingsEqual, eccentric and lateral tees, T-pieces, Y-pieces, wye pieces, piggable wyes.
- Shafts and stepped partsForged shafts, spindles, stepped shafts, upset and flanged forgings.
Size capability
| Product form | Size range | Single-piece weight |
|---|---|---|
| Round bars and shafts | Dia. 80-1200 mm, length to 12,000 mm | up to 20 t |
| Seamless rolled rings | OD 300-4000 mm, height to 1000 mm | up to 15 t |
| Hollow bars and sleeves | OD 150-1500 mm, ID from 60 mm | up to 15 t |
| Discs, flanges and blocks | Dia. to 2500 mm, thickness to 800 mm | up to 20 t |
| Valve bodies and fittings | To drawing, DN 50 to DN 1200 | up to 12 t |
Sizes outside these ranges can often be produced. Send the drawing for a feasibility check before placing the order.
Manufacturing and inspection
Production route
- Steelmaking. Electric arc furnace with ladle refining and vacuum degassing (EAF, LF, VD). Electroslag remelting is used where the specification or section size requires it.
- Open-die forging. Hydraulic press forging with a controlled forging ratio, normally 3:1 or higher, so that the cast structure is broken down through the full section.
- Heat treatment. In-house normalizing and tempering in furnaces with calibrated multi-point recording. Charts are supplied with the certificate.
- Machining. Rough turning, boring and milling to the specified stock allowance, or finish machining to drawing.
Inspection and testing
- Ladle and product chemical analysis by optical emission spectrometry
- Tensile, impact and hardness testing from integral or prolongation test blocks
- Ultrasonic testing to EN 10228-3 or ASTM A388, acceptance class per specification
- Magnetic particle inspection to EN ISO 17638 or ASTM E709
- Dimensional inspection report against the drawing
- Grain size, macro-etch and microstructure examination on request
Certification
Every shipment carries an EN 10204 Type 3.1 mill test certificate covering heat number, chemical analysis, heat-treatment record, mechanical results and NDT results. EN 10204 Type 3.2 certification witnessed by a third-party inspection body such as TUV, Bureau Veritas, SGS, Lloyd's Register or DNV is available, and is agreed at enquiry stage because it affects the production schedule.
Applications of 1.4901
1.4901 was developed for ultra-supercritical steam cycles operating at around 600 °C, and most applications are in that field.
- Fossil-fired power plant. Superheater and reheater headers, main steam piping, hot reheat piping, header stubs and forged tees.
- Boiler pressure parts. Thick-wall outlet headers, forged nozzles and transition pieces.
- High-temperature valves. Valve bodies, bonnets, seats and stems for main steam and hot reheat service, normally to ASTM A182 F92.
- Steam turbine plant. Casings, forged rings and bolting for high-temperature stages.
- Petrochemical and refinery. Hydrogen service and elevated-temperature pressure components where 9 % Cr steel is specified.
- Waste-to-energy and biomass boilers. Plant operating at raised steam conditions for higher cycle efficiency.
Welding and machining 1.4901
Welding
1.4901 is an air-hardening martensitic steel and requires controlled welding procedures. The values below are typical practice for Grade 92. The binding values for any joint are those in the qualified WPS.
| Parameter | Typical practice |
|---|---|
| Preheat | min 200 °C, 250 °C for sections above 50 mm |
| Interpass temperature | max approx. 300 °C |
| Cool-down before PWHT | Cool to 80-100 °C and hold, so the weld transforms fully to martensite |
| PWHT | 750-780 °C, 1 hour per 25 mm of thickness, 2 hours minimum |
| Consumables | Matching 9Cr-W filler metals. Grade 91 (B9) consumables require engineering approval before substitution. |
| ASME Section IX | P-No. 15E |
Two problems account for most in-service failures on this grade. The first is PWHT started before the weld has cooled below the martensite finish temperature, which leaves untempered martensite in the joint. The second is Type IV cracking in the fine-grained heat-affected zone under long-term creep. Both are controlled by the welding and heat-treatment procedure rather than by the base material.
Machining
At 220-250 HBW in the tempered condition, 1.4901 machines in a similar way to a tough medium-alloy steel. Rigid setups, positive-rake carbide tooling, moderate cutting speeds and adequate depth of cut are recommended so that the tool cuts below the work-hardened layer. Where rough-machined parts are supplied, the stock allowance is agreed in advance so that sufficient material remains for finish operations after any heat-treatment distortion.
Frequently asked questions about 1.4901
Common questions on 1.4901 specification and supply.
What is 1.4901 steel?
1.4901 is the EN material number for X10CrWMoVNb9-2, a creep-strength-enhanced ferritic steel that is martensitic in the delivered condition. It contains 8.5-9.5 % chromium, 1.5-2.0 % tungsten and 0.3-0.6 % molybdenum, with vanadium, niobium and controlled boron and nitrogen. It is supplied normalized and tempered and is used for high-temperature pressure parts in power plant, normally up to 600-620 °C.
What is the ASTM equivalent of 1.4901?
1.4901 / X10CrWMoVNb9-2 corresponds to ASTM and ASME Grade 92, UNS K92460. The product-form designations are ASTM A182 F92 for forged flanges, fittings and valve parts, ASTM A336 F92 for forgings for pressure vessels, ASTM A335 P92 for seamless pipe, ASTM A213 T92 for tube, ASTM A369 FP92 for forged and bored pipe and ASTM A234 WP92 for wrought fittings. Composition limits are close but not identical in every standard, so the governing specification should be confirmed before one is substituted for another.
Is 1.4901 a stainless steel?
No. Some material databases list 1.4901 under stainless steels because it carries a 1.4xxx EN material number. With 8.5-9.5 % chromium it is classified as a creep-strength-enhanced ferritic martensitic heat-resistant steel. It is selected for creep strength at high temperature and has no useful corrosion resistance in wet service.
What is the difference between 1.4901 (P92) and 1.4903 (P91)?
1.4901 (Grade 92) contains 1.5-2.0 % tungsten and 0.3-0.6 % molybdenum. 1.4903 (Grade 91) contains no specified tungsten and 0.85-1.05 % molybdenum. The tungsten addition together with controlled boron gives Grade 92 approximately 25-30 % higher creep rupture strength at 600 °C, which permits thinner wall sections for the same steam conditions. Grade 91 is lower in cost, easier to weld and more widely available.
What is the maximum service temperature of 1.4901?
1.4901 is normally specified for continuous service up to 600-620 °C. Above that range steam-side oxidation resistance rather than creep strength becomes the limiting factor and austenitic stainless or nickel-base grades are generally selected.
Which standards cover 1.4901 / X10CrWMoVNb9-2?
The main European standards are EN 10216-2 for seamless tubes for pressure purposes, EN 10222-2 for steel forgings for pressure purposes in ferritic and martensitic steels, and EN 10028-2 for flat products. The equivalent American specifications are ASTM and ASME A182 F92, A336 F92, A335 P92, A213 T92, A369 FP92 and A234 WP92. For welding qualification, Grade 92 falls under ASME Section IX P-No. 15E.
Do 1.4901 welds require preheat and post-weld heat treatment?
Yes. 1.4901 is an air-hardening martensitic steel. Typical practice is a minimum preheat of 200 °C, interpass temperature limited to about 300 °C, a controlled cool-down to 80-100 °C so that the weld transforms fully to martensite, then post-weld heat treatment at 750-780 °C for one hour per 25 mm of thickness with a two-hour minimum. Matching 9Cr-W consumables are required and all parameters are fixed by the qualified WPS.
What 1.4901 forged products can Jiangyin Jiangnan Metal supply?
Jiangyin Jiangnan Metal Co., Ltd. supplies 1.4901 as open-die forged round, square, flat and hexagonal bars; hollow bars, sleeves, bushings, cylinders, shells and casings; seamless rolled rings; forged flanges, blocks, discs and plates; valve bodies, bonnets, seats, seat rings and stems; and forged equal, eccentric and lateral tees, Y-pieces, wyes and piggable wyes. Parts are made to drawing or to ASTM, ASME, EN and DIN specifications.
What certification is supplied with 1.4901 forgings?
Each shipment is supplied with an EN 10204 Type 3.1 mill test certificate covering heat analysis, product analysis, heat-treatment record, mechanical test results and non-destructive testing. EN 10204 Type 3.2 certification witnessed by a third-party inspection body such as TUV, Bureau Veritas, SGS, Lloyd's Register or DNV is available on request and is stated at the enquiry stage.
How do I request a quotation for 1.4901 forgings?
Send the enquiry to sales@steelforgepieces.com or call +86-189-2135-9659 with the grade and standard, the drawing or rough dimensions with machining allowance, the quantity and single-piece weight, the required delivery condition and NDT, the certification level and the destination port. Quotations are normally returned within one working day.
Request a quotation for 1.4901 forgings
Send a drawing for a price, weight and delivery date. If no drawing is available, rough dimensions and the governing standard are sufficient to start.
Information required
- Grade and governing standard: 1.4901, X10CrWMoVNb9-2, A182 F92, A336 F92 or customer specification
- Drawing, or rough dimensions with the required machining allowance
- Quantity and single-piece weight
- Delivery condition: as forged, rough machined or finish machined
- Required NDT and acceptance class
- Certification level: EN 10204 3.1 or 3.2, and the inspection body if 3.2
- Destination port and required delivery date
- CompanyJiangyin Jiangnan Metal Co., Ltd., open-die forging factory
- AddressNo.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- Phone+86 189 2135 9659, WeChat and WhatsApp on the same number
- Emailsales@steelforgepieces.com
- Websitewww.steelforgepieces.com
- ResponseQuotations normally within one working day