Martensitic heat-resistant steel datasheet
23H12MNF steel
23H12MNF is a Polish PN designation for a 12% chromium martensitic heat-resistant steel alloyed with molybdenum, nickel and vanadium. It is the standard material of construction for steam turbine components and heat-resistant screws and bolting. The vanadium addition improves the creep and high-temperature strength of the steel. 23H12MNF corresponds to EN X22CrMoV12-1, Werkstoff number 1.4923.
- Composition: C 0.20–0.26%, Cr 11.0–12.5%, Mo 0.80–1.20%, Ni 0.30–0.80%, V 0.25–0.35%, balance Fe.
- Equivalent to: X22CrMoV12-1, 1.4923, and ASTM A565 Grade 615 as a close match.
- Used for: steam turbine blades, rotor shafts, wheels and gland seal rings, heat-resistant bolts and studs, compressor impellers, and high-temperature valve parts.
- Service temperature: continuous use to approximately 540–565 °C.
- Corrosion: PRE 13.64 to 16.46. Resists steam and rural or urban atmospheres. Not suitable where chlorides or salts are present.
- Forged by: Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory in Jiangyin, Jiangsu, China, supplying 23H12MNF bars, rings, hollow bars, discs, shafts and valve parts made to drawing.
Last reviewed on 10 September 2026 by Jiangyin Jiangnan Metal Co., Ltd.
Chemical composition of 23H12MNF
The limits below are the PN specification ranges for 23H12MNF. Every heat we forge is analysed and the actual ladle analysis is reported on the EN 10204 3.1 certificate that ships with the parts.
| CCarbon | MnManganese | SiSilicon | PPhosphorus | SSulphur | CrChromium | MoMolybdenum | NiNickel | VVanadium | NbNiobium | WTungsten |
|---|---|---|---|---|---|---|---|---|---|---|
| 0.20–0.26 | 0.30–0.80 | 0.10–0.50 | ≤ 0.035 | ≤ 0.035 | 11.0–12.5 | 0.80–1.20 | 0.30–0.80 | 0.25–0.35 | ≤ 0.05 | ≤ 0.60 |
Chromium and molybdenum provide the high-temperature strength. Vanadium forms fine carbides that raise creep resistance. Nickel helps heavy sections harden through to a fully martensitic structure.
23H12MNF equivalent grades
23H12MNF is most often cross-referenced against the German and European designation for the same 12Cr-Mo-V steel. Buyers working to ASTM will usually find Grade 615 the nearest match.
| Standard / country | Designation | Relationship |
|---|---|---|
| PN (Poland) | 23H12MNF | This grade |
| EN 10269 / DIN 17240 (Europe) | X22CrMoV12-1 | Direct equivalent |
| Werkstoff number | 1.4923 | Direct equivalent |
| ASTM A565 (USA) | Grade 615 | Close equivalent |
| Related, not identical | X20CrMoWV12-1 (1.4935), ASTM A565 Grade 616 | Deliberate tungsten addition, higher creep strength, different specification |
Cross-references are given for guidance. Composition and property ranges differ between standards, so confirm the grade against your governing specification before ordering. If your drawing calls out a designation not listed here, send it to us and we will confirm the cross-reference in writing before production starts.
Mechanical properties
Typical room-temperature properties for 23H12MNF in the quenched and tempered condition. Actual values depend on section size and on the tempering temperature chosen, and are agreed on the order before production.
| Property | Typical value |
|---|---|
| Tensile strength, Rm | 800–950 MPa |
| Proof strength, Rp0.2 | ≥ 600 MPa |
| Elongation, A | ≥ 14% |
| Reduction of area, Z | ≥ 50% |
| Impact energy, KV at 20 °C | ≥ 27 J |
| Hardness | approx. 248–302 HB |
| Density | approx. 7.70 g/cm³ |
| Maximum continuous service temperature | approx. 540–565 °C |
Heat treatment and forging practice
23H12MNF is an air-hardening steel. Heavy sections must be cooled slowly after forging and annealed before machining, or they will crack. We heat treat in-house and record the actual cycle on the certificate.
| Operation | Temperature | Cooling |
|---|---|---|
| Forging, start | 1100–1150 °C | Not applicable |
| Forging, finish | not below 900 °C | Slow cool in furnace or ash |
| Soft annealing | 800–840 °C | Furnace cool |
| Austenitising and hardening | 1020–1070 °C | Oil or air quench |
| Tempering | 680–780 °C | Air cool |
| Stress relieving | approx. 30 °C below the tempering temperature | Furnace or air cool |
Tempering below about 600 °C is avoided on service-critical parts because it can leave the steel prone to temper embrittlement. If you state the properties required on the order, we will set the cycle to meet them.
Corrosion resistance
The pitting resistance equivalent of 23H12MNF is 13.64 to 16.46. The chromium content is low for a stainless steel, so corrosion resistance is limited. It is sufficient in rural and urban atmospheres provided no chlorides or salts are present, and it is sufficient in steam, which is the service the grade was developed for. 23H12MNF should not be selected for marine, chloride-bearing or acidic conditions. For those conditions we normally quote a duplex, super-austenitic or nickel-base grade instead.
23H12MNF forms we forge
Jiangyin Jiangnan Metal Co., Ltd. forges each item below to the customer's drawing or dimensional envelope. There is no minimum order quantity, and single pieces for turbine overhauls and spares are accepted.
Bars
Forged round bars, rods, square and rectangular bars, flat bars and hex bars.
Rings
Seamless rolled rings, forged rings, steam turbine gland seal rings and guide rings.
Hollow sections
Forged hollow bars, sleeves, bushes and bushings, pipes and tubes, barrels, casings, shells, cylinders, hubs and housings.
Discs and blocks
Forged discs, disks, blocks and plates, rough machined or with a finish allowance.
Rotating parts
Turbine and compressor blades, impellers, rotor shafts, wheels, bolts and studs.
Valve components
Gate, check and control valve bodies and bonnets, valve stems, spindles, rods, valve seats and valve discs.
Applications of 23H12MNF
23H12MNF is specified where a component must retain its strength over long service periods at temperature in steam. The main uses are:
- Steam turbines: blades, rotor shafts, wheels, discs, gland seal and sealing guide rings.
- Heat-resistant fastening: bolts, studs and screws for flanged joints running hot.
- Compressors: impellers and blading in high-temperature stages.
- High-temperature valves: bodies, bonnets, stems, spindles, seats and discs for steam service.
- Power plant pressure parts: components requiring creep strength together with resistance to steam oxidation.
Quality and testing
Each 23H12MNF forging is supplied with an EN 10204 3.1 mill test certificate showing the heat number, the ladle chemical analysis, the heat treatment condition and the mechanical test results. The following can be added when you specify them on the order:
- Ultrasonic testing to your acceptance class
- Magnetic particle or dye penetrant inspection
- Hardness survey across the section
- Charpy impact testing at ambient or specified temperature
- Grain size, macro-etch and intergranular corrosion testing
- Third-party inspection by SGS, BV, TÜV or your own inspector at our works
Frequently asked questions about 23H12MNF
What is 23H12MNF steel?
23H12MNF is a Polish PN designation for a martensitic heat-resistant steel containing approximately 12% chromium with molybdenum, nickel and vanadium additions. It is the standard construction material for steam turbine components and heat-resistant bolting. The vanadium addition improves creep strength and high-temperature strength. It corresponds to EN X22CrMoV12-1 and Werkstoff number 1.4923.
What is the equivalent grade of 23H12MNF?
23H12MNF corresponds directly to EN and DIN X22CrMoV12-1, Werkstoff number 1.4923. ASTM A565 Grade 615 is a close North American counterpart. Related but not identical grades include X20CrMoWV12-1 (1.4935) and ASTM A565 Grade 616, which contain deliberate tungsten additions. Ranges differ slightly between standards, so confirm against your governing specification before ordering.
What is the chemical composition of 23H12MNF?
23H12MNF contains carbon 0.20 to 0.26%, manganese 0.30 to 0.80%, silicon 0.10 to 0.50%, phosphorus max 0.035%, sulphur max 0.035%, chromium 11.0 to 12.5%, molybdenum 0.80 to 1.20%, nickel 0.30 to 0.80%, vanadium 0.25 to 0.35%, niobium max 0.05% and tungsten max 0.60%, with the balance iron.
What is 23H12MNF used for?
23H12MNF is used for steam turbine blades, rotor shafts, wheels, discs and gland seal rings, for heat-resistant bolts, studs and screws, for compressor impellers, and for high-temperature valve bodies, bonnets, stems and seats. Jiangyin Jiangnan Metal Co., Ltd. forges all of these forms to customer drawing.
Is 23H12MNF a stainless steel?
23H12MNF is normally classified as a martensitic heat-resistant steel rather than a corrosion-resistant stainless steel. Its chromium content of 11.0 to 12.5% gives a pitting resistance equivalent of 13.64 to 16.46, which is sufficient in rural and urban atmospheres and in steam, but not in chloride or salt-bearing environments.
What heat treatment is applied to 23H12MNF forgings?
23H12MNF forgings are typically austenitised at about 1020 to 1070 °C and quenched in oil or air, then tempered at about 680 to 780 °C and air cooled. The exact cycle depends on section size and the mechanical properties required. Jiangyin Jiangnan Metal performs heat treatment in-house and reports the actual cycle and results on the EN 10204 3.1 certificate.
What is the maximum service temperature of 23H12MNF?
23H12MNF is normally applied continuously up to about 540 to 565 °C, which is why it is a standard steam turbine and heat-resistant bolting material. Above that range the creep strength drops and 9 to 12% Cr grades with tungsten additions, or nickel-base alloys, are usually specified instead.
Who supplies forged 23H12MNF parts?
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, supplies open-die forged 23H12MNF bars, rings, hollow bars, discs, blocks, shafts and valve components made to drawing. Enquiries go to sales@steelforgepieces.com or +86 189 2135 9659.
What sizes and shapes can be forged in 23H12MNF?
Jiangyin Jiangnan Metal forges 23H12MNF as round, square, rectangular, flat and hex bars, seamless rolled rings, hollow bars, sleeves, bushings and cylinders, discs, blocks and plates, and near-net-shape shafts and valve parts. Send a drawing or the finished dimensions with the required tolerance and test scope, and we confirm the achievable size range and the price.
What certification is supplied with 23H12MNF forgings?
Forgings are supplied with an EN 10204 3.1 mill test certificate covering heat number, chemical analysis, heat treatment condition and mechanical test results. Ultrasonic testing, magnetic particle or dye penetrant inspection, hardness surveys, impact testing and third-party inspection can be added when specified on the order.
Request a quotation for 23H12MNF forgings
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China. We forge 23H12MNF and the equivalent grades X22CrMoV12-1 and 1.4923 into bars, seamless rolled rings, hollow bars, discs, blocks, shafts, turbine parts and valve components, made to drawing and certified to EN 10204 3.1.
Send the drawing, or the outside diameter, inside diameter, length and quantity you need, together with the heat treatment condition and test scope. We reply with price, weight, lead time and the mill certificate scope.
- Telephone, WhatsApp and WeChat
- +86 189 2135 9659
- Factory address
- No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- Website
- www.steelforgepieces.com
Related grades
Grades that are quoted alongside 23H12MNF, either as substitutes at higher temperature or where chloride resistance is needed: