P92 / F92 Forgings (UNS K92460)

P92 / F92 key data

Grade names

P92 (pipe), F92 (forgings), T92 (tube), WP92 (butt-weld fittings), Grade 92

Nominal chemistry

9Cr-0.5Mo-1.8W-V-Nb with controlled boron and nitrogen

UNS number

K92460

EN designation

X10CrWMoVNb9-2, material number 1.4901

Chinese designation

10Cr9MoW2VNbBN (GB/T 5310)

Forging standards

ASTM A182 / ASME SA-182 F92; ASTM A336 / ASME SA-336 F92

Steel type

9% chromium creep-strength-enhanced ferritic (CSEF) steel, tempered martensite

Delivery condition

Normalized and tempered

Minimum strength

620 MPa tensile, 440 MPa yield (ASTM A182 F92)

Service temperature

Steam up to about 620 °C (1150 °F)

Certificate

EN 10204 3.1 as standard; 3.2 with third-party witness on request

What P92 is and when to specify it

Grade 92 was developed in Japan, originally under the name NF616, as a stronger successor to Grade 91 for supercritical and ultra-supercritical boilers. Its strength at temperature comes from a tempered martensite matrix, fine vanadium and niobium carbonitride precipitates, tungsten in solid solution, and boron, which slows the coarsening of M₂₃C₆ carbides near grain boundaries.

The 9% chromium gives better oxidation and corrosion resistance than 2¼Cr-1Mo Grade 22. As a ferritic steel, P92 conducts heat better and expands less than austenitic stainless steels, so thick-walled headers, pipes and valve bodies see lower thermal stress during start-up and load changes.

Specify P92 / F92 when

• Steam temperature is in the 580–620 °C range and Grade 91 would need a much thicker wall.
• A forged valve body, tee, Y-piece or header end must weld into P92 pipe or T92 tube with matching filler metal and one post-weld heat treatment.
• The part is a thick-section pressure component where lower thermal expansion than austenitic steel reduces fatigue from load cycling.

Specify another grade when

• Service stays below about 580 °C. Grade 91 (F91 / P91) is usually the lower-cost choice.
• Metal temperature exceeds about 620 °C. Steam-side oxidation and long-term creep strength limit 9% chromium steels; austenitic stainless steels or nickel alloys such as Inconel 617 are used instead.
• The part carries load at room temperature only. A quenched and tempered steel such as 42CrMo4 or AISI 4140 is stronger and cheaper.

Chemical composition of P92 / F92

Heat-analysis limits shared by ASTM A182 F92 and ASTM A335 P92, in weight percent. Tungsten, highlighted, is the element that separates Grade 92 from Grade 91.

Aluminum, titanium and zirconium limits are those of current editions; older editions allowed up to 0.04% aluminum. The edition named on the purchase order governs. Heat analysis is reported on every mill certificate, and product analysis on the forging is available on request.

Mechanical properties of P92 / F92

Minimum room-temperature requirements after normalizing and tempering. ASTM A182 covers forged flanges, fittings, valves and parts; ASTM A335 covers seamless pipe.

ASTM A336 F92, used for larger forgings for pressure and high-temperature parts, locates test specimens by forging size and applies separate ductility limits to transverse tests. State the test direction and specimen location on the order.

Behavior at temperature

At service temperature, design is governed by creep-rupture strength rather than short-term tensile strength. Allowable stresses for Grade 92 come from the design code, such as ASME Section II Part D. Elevated-temperature tensile and stress-rupture tests can be added to the order.

Heat treatment of P92 / F92

Normalizing dissolves carbides and turns the structure to austenite, which transforms to martensite on air cooling. Tempering then precipitates the fine carbonitrides that give Grade 92 its creep strength. The 800 °C tempering ceiling keeps the steel below its lower critical temperature (Ac1). Tempering above Ac1 re-austenitizes part of the structure, which cools to fresh untempered martensite and lowers creep strength. That is also why nickel and manganese, which lower Ac1, are held to 0.40% and 0.60%.

Hardness is measured after tempering and reported on the certificate with the heat treatment record.

P92 equivalent grades and standards

Grade 92 is designated by product form. Order forgings to a forging specification, ASTM A182 or ASTM A336, rather than to the pipe specification ASTM A335, so the correct tests and certificate apply.

EN 1.4901 and GB 10Cr9MoW2VNbBN are close to ASTM Grade 92 but not identical in every limit. Name one standard on the order, and the forging is tested and certified to that standard.

P92 vs P91

Grade 91 and Grade 92 are used for the same parts of power plant piping. Grade 92 adds tungsten and boron and has higher creep strength.

P92 / F92 forgings we produce

We forge every item below to the customer’s drawing or sketch. Open-die forging needs no closed dies, so there is no tooling charge for single pieces or prototypes.

• Seamless rolled rings

  Rolled without a weld seam for flange rings, valve seat rings, casing rings and spacer rings.

• Round, square, flat and hex bars

  Forged and rough turned or machined, cut to length, including stock for re-forging.

• Hollow bars, sleeves and forged pipe

  Trepanned or mandrel-forged hollows for bushings, barrels, shells, cylinders, housings and heavy-wall pipe sections.

• Discs, blocks, plates and flanges

  Upset-forged discs and blocks for blind flanges, covers, hubs and flange blanks.

• Valve components

  Bodies, bonnets, stems, seats and seat rings for high-pressure gate, globe, check and turbine bypass valves.

• Tees, Y-pieces and laterals

  Forged blanks for equal and reducing tees, laterals and Y-pieces in main steam and hot reheat lines.

Plant capability

Forging equipment: 1 t, 3 t, 5 t and 9 t open-die forging hammers, a 5,000 t hydraulic press, and 3 m and 6 m ring rolling mills. Single pieces weigh from 10 kg to 15,000 kg.

How P92 forgings are made

1. Steelmaking Grade 92 is melted by electric arc furnace with ladle refining and vacuum degassing. Electroslag remelting is added where the specification or section size calls for it.
2. Material check Heat chemistry is checked against the Grade 92 limits before the ingot or billet is heated.
3. Open-die forging Forged on hammers or the hydraulic press with a controlled reduction ratio that closes internal porosity and gives a grain flow following the part shape. Rings are rolled seamless.
4. Normalizing and tempering Austenitized at 1040–1080 °C and air cooled, then tempered at 730–800 °C. Hardness is checked after tempering.
5. Ultrasonic testing Examined to ASTM A388, EN 10228-3 or the customer’s class. For ASTM A336 F92 hollow forgings, ultrasonic supplement S20 or S22 of ASTM A788 is mandatory.
6. Machining Rough or finish machined to the drawing.
7. Testing and certification Tensile, hardness and NDT results and the heat treatment record are issued on an EN 10204 3.1 certificate, or 3.2 with a third-party witness on request.

Where P92 forgings are used

Testing, inspection and certification

• Chemical analysis. Heat analysis on every certificate; product analysis on the forging on request.
• Tensile and hardness. Room-temperature tensile strength, yield strength, elongation and reduction of area, and Brinell hardness after tempering. Elevated-temperature tensile and stress-rupture tests on request.
• Ultrasonic testing. ASTM A388, EN 10228-3 or customer class; ASTM A788 S20 or S22 for ASTM A336 F92 hollow forgings.
• Surface examination. Magnetic particle to ASTM A275 or liquid penetrant to ASTM E165, as ordered.
• Metallography. Grain size to ASTM E112 and microstructure checks on request.
• Certification. EN 10204 3.1 as standard; EN 10204 3.2 witnessed by TÜV, BV, LR, SGS or DNV on request. The heat number is stamped on each forging for traceability.

Request a quote for P92 / F92 forgings

Send a drawing, a sketch, or dimensions and quantity for a quotation.

Include if known: the specification (ASTM A182 F92, ASTM A336 F92 or EN 1.4901), product form, dimensions with machining allowance, quantity, heat treatment condition, ultrasonic class and test direction, certificate type (EN 10204 3.1 or 3.2) and required delivery date.

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