SteelForgePieces
Material No. 1.4903 · EN 10302-2008

Forged 1.4903 Steel
Components & Stock

Open-die forged bars, seamless rings, flanges, valve parts and custom fittings in X10CrMoVNb9-1 / Grade P91 martensitic creep-resistant steel. Manufactured in China to international standards. Custom sizes on request.

Request a Quote →
EN Designation
X10CrMoVNb9-1
ASTM Equivalent
P91 / T91 / F91 / Grade 91
Standard
EN 10302-2008
EN 10216-2:2014
Chromium Content
8 – 9.5 %
Max. Service Temp.
~650 °C

What is 1.4903 Steel?

1.4903, also known by its EN designation X10CrMoVNb9-1, is a martensitic, creep-resistant chromium steel standardised under EN 10302-2008. It belongs to the family of 9% chromium steels — the same family as the widely-used ASTM Grade P91 / T91 — and is engineered for sustained high-temperature service in the range of 550–650 °C.

The alloy derives its excellent creep strength from a carefully balanced combination of chromium (8–9.5%), molybdenum (0.85–1.05%), vanadium (0.18–0.25%) and niobium (0.06–0.1%), which form fine carbide and nitride precipitates that resist dislocation movement at elevated temperatures. It is widely specified in power generation, chemical processing and oil & gas applications where long-term structural integrity at high temperatures is critical.

Available Forged Products in 1.4903

⬛

Round Bars & Rods

Solid round, square, flat and hex bars

🔩

Hollow Bars & Sleeves

Bushings, pipes, tubings, shells, cylinders

⭕

Seamless Rolled Rings

Open-die and rolled ring forgings

🔶

Flanges & Discs

Forged flanges, blocks, discs and plates

🔧

Valve Components

Seats, stems, bodies, bonnets, seat rings

🔀

Pipe Fittings

Tees, Y-pieces, eccentric/concentric reducers, wye pieces

🏭

Custom Forgings

Any shape — drawings and specs accepted

Chemical Composition — 1.4903 (EN 10302-2008)

Weight % — all values are wt% unless noted
CSiMnNi PSCrMo VNNbAl
0.08–0.12 max 0.5 0.3–0.6 max 0.4 max 0.025 max 0.015 8–9.5 0.85–1.05 0.18–0.25 0.03–0.07 0.06–0.1 max 0.03
Additional limits per EN 10216-2:2014 — Si ≥ 0.2; P ≤ 0.02; S ≤ 0.005; Al ≤ 0.02; Cu ≤ 0.3; Ti ≤ 0.01

Mechanical Properties — 1.4903

Tensile Strength (Rm) by Thickness

Property ≤ 60 mm 60–150 mm 150–250 mm
Rm — Tensile strength (MPa) 580–760550–730520–700
Rm — Tensile strength (+QT) (MPa) 620–850

Yield Strength (ReH / Rp0.2) by Thickness

Property ≤ 60 mm 60–250 mm
ReH — Min. yield strength (MPa) 445435
Rp0.2 — 0.2% proof strength (+QT) (MPa) 450

Impact Energy (KV) — Charpy

Direction / Condition −20 °C0 °C+20 °C
KV transverse (+NT) (J) 273427–40
KV longitudinal (+NT) (J) ——40
PropertyValue
A — Min. elongation at fracture (%)18–20

1.4903 Equivalent & Cross-Reference Grades

1.4903 aligns with the well-known Grade P91 family across international standards:

EN (Material No.)
1.4903
EN (Name)
X10CrMoVNb9-1
ASTM A335 / ASME
Grade P91
ASTM A213
Grade T91
ASTM A182
Grade F91
Common name
9Cr-1Mo-V (Mod.)

Typical Applications of 1.4903 / P91

  • Steam turbine rotors and casings
  • High-pressure boiler headers and piping
  • Main steam and hot reheat lines
  • Heat recovery steam generators (HRSG)
  • Pressure vessels (petrochemical)
  • Valve bodies and pressure-retaining parts
  • Collector tubes in thermal power plants
  • Refinery and reactor pressure piping

Frequently Asked Questions

1.4903 (X10CrMoVNb9-1) is a martensitic, creep-resistant 9% chromium steel used primarily in high-temperature applications up to ~650 °C. It is the EN equivalent of ASTM Grade P91 and is used for steam turbine components, boiler piping, pressure vessels and valve parts in power generation and the oil & gas industry.
1.4903 corresponds to Grade P91 (ASTM A335/ASME), Grade T91 (ASTM A213 — seamless tubes), and Grade F91 (ASTM A182 — forgings). All are 9Cr-1Mo-V modified steels with essentially the same composition.
We supply open-die forged and rolled ring forgings in 1.4903 including: round bars, square bars, flat bars, hex bars, hollow bars, sleeves, bushings, seamless rolled rings, flanges, discs, plates, valve seats, valve stems, valve bodies, and custom fittings such as tees, Y-pieces and reducers.
Per EN 10302-2008: Rm = 580–760 MPa (≤60 mm), 550–730 MPa (60–150 mm), 520–700 MPa (150–250 mm). After quench and temper (+QT): Rm = 620–850 MPa. Minimum yield strength ReH = 445 MPa (≤60 mm) / 435 MPa (60–250 mm).
1.4903 contains 8–9.5% chromium — below the 10.5% minimum threshold that defines stainless steel. It is therefore classified as a creep-resistant alloy steel rather than a stainless steel, although it does offer moderate oxidation resistance at elevated temperatures.