What is the difference between A213 T91 and T92
Mar 17, 2025
What is the difference between A213 T91 and T92 boiler pipe
I. Chemical composition adjustment
Molybdenum (Mo) and tungsten (W) content:
T91: The molybdenum content is 0.85%~1.05%.
T92: Reduce the molybdenum content on the basis of T91 and increase the tungsten content to 1.5%~2.0% to enhance the solid solution strengthening effect.
Other alloying elements:
T92 additionally adds more vanadium (V), niobium (Nb) and nitrogen (N) to form more MX phases (e.g., carbon-nitride of V/Nb) and strengthen the intracrystalline matrix.
II. High temperature properties and strength
Permissible stress:
The permissible stress of T92 at 600°C is about 20%~30% higher than that of T91, which is suitable for supercritical/super-supercritical units with higher parameters.
Applicable temperature range:
T91: Long-term use temperature ≤600℃.
T92: Can withstand high temperatures of 620°C, with significantly higher enduring strength.
Oxidation resistance:
T92 further improves the resistance to steam oxidation by optimising the Cr content (9%~10%).
III. Organisation and Strengthening Mechanism
Microstructure:
Both are ferritic-martensitic steels, but T92 has a more stable organisation through W-Mo composite solid solution strengthening and diffuse precipitation of MX phase.
Heat treatment process:
T92 requires more stringent heat treatment (e.g. normalising + tempering) to ensure uniform distribution of carbides (M23C6) and MX phases.
IV. Application Scenarios
T91:
Mainly used in superheater, reheater and petrochemical pipeline of subcritical and supercritical boilers.
T92:
Applicable to high-temperature components of ultra-supercritical units (steam temperature ≥580℃), such as main steam piping and reheater coupling box.
V. International Standard Correspondence
T91: corresponds to ASTM A213/ASME SA213, GB 5310 (10Cr9Mo1VNb).
T92: corresponds to EN 10216-2 (X10CrWMoVNb9-2) and JIS G3467.
Summary: T92 is superior to T91 in high-temperature strength, oxidation resistance and applicable temperature range by optimising the W-Mo ratio and reinforcing phase design, and is the material of choice for higher parameter power station boilers.
