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Steel 15X25T as equivalent of grade 1.4749

Steel 15X25T

Ferritic heat-resistant steel · maximum service temperature 1150 °C
Steel type
Ferritic heat-resistant
DIN
15Cr25Ti
PN
H25T
EN standard (equivalent)
1.4749
Tmax
1150 °C
Steel 15X25T (Russian/PN designation: H25T, DIN: 15Cr25Ti) is stabilized with titanium. Its EN equivalent is grade 1.4749, in which the stabilizing element is aluminum (Al) instead of titanium.

Corrosion characteristics

Steel 15X25T offers resistance to aggressive agents present at elevated industrial temperatures:

  • Exceptionally good resistance to reducing sulfurous gases
  • Very good resistance to oxidation in air
  • Good resistance to oil-ash corrosion
  • Good resistance to attack by molten metals — copper, lead, tin

Service temperature range

Steel 15X25T can be used in continuous service at temperatures up to 1150 °C (2102 °F). This is among the higher ranges for ferritic steels, making this grade attractive for furnace components, burners, desulfurization systems, and parts subject to prolonged exposure to hot gases.

Note — creep at elevated temperatures. Steel H25T exhibits high creep elongation (often exceeding 100%) and low creep resistance. At service temperatures above 700 °C (1290 °F), even the self-weight of tubes can generate stresses leading to significant deformation. Allowance for substantial creep deformation well before fracture must be made, and tube support design must be addressed accordingly.

Mechanical strength and low-temperature embrittlement

H25T, like other ferritic chromium steels, has lower strength than austenitic stainless steels in the as-delivered condition. The ductile-to-brittle transition temperature is approximately 100–150 °C (210–300 °F), meaning that below this range the steel is more susceptible to brittle fracture.

Note — repairs and handling. After a period of service, room-temperature strength may decrease further. During any repairs, assembly, and transportation, large impact stresses and rapid temperature changes must be avoided.

Comparison with grade 1.4749

Steel 15X25T is frequently used interchangeably with grade 1.4749. Both grades have a similar chromium content (~25%) and very comparable heat-resistant properties, but differ in the stabilizing element:

  • 15X25T (H25T) — stabilized with titanium (Ti)
  • 1.4749 — stabilized with aluminum (Al)

Chemical composition comparison

Values in wt.%. Empty fields indicate no requirement in the grade specification.

Element 15X25T 1.4749
Min. Max. Min. Max.
Carbon (C) — 0.15 0.15 0.20
Silicon (Si) — 1.00 — 1.00
Manganese (Mn) — 0.80 — 1.00
Phosphorus (P) — 0.035 — 0.04
Sulfur (S) — 0.025 — 0.015
Chromium (Cr) 24.00 27.00 26.00 29.00
Nickel (Ni) — 0.60 — —
Titanium (Ti) 5×C 0.90 — —
Aluminum (Al) — — 0.15 0.25

Recommended applications

Grade 1.4749 (and equivalently 15X25T) is recommended for structural components resistant to scale build-up at temperatures up to approximately 1100 °C and heavily exposed to sulfurous gases. The propensity for carburization in reducing gases is very low, making these grades the appropriate choice for:

  • Industrial furnace components and combustion chambers
  • Flue gas desulfurization systems
  • Heat exchangers operating in sulfurous atmospheres
  • Refinery and petrochemical components
  • Grates, burners, and thermocouple sheaths

Technical information is provided for reference purposes. Prior to using this material in an actual installation, relevant industry standards (PN-EN 10095, ASTM A268) should be consulted.