What is SA213 T91 material

What is SA213 T91 material?

I. Material type and classification
Ferritic-martensitic heat-resistant steel: Improved on the basis of 9Cr-1Mo (T9) steel, the performance is optimised by the addition of vanadium (V), niobium (Nb), nitrogen (N) and other elements, which belongs to the steel grade in the ASME SA-213 standard.
Application classification: mainly used for high temperature pressure parts, such as boiler tubes, nuclear power equipment.
Second, the chemical composition
Main components (mass per cent):
Carbon (C): 0.06% ~ 0.15% (strictly limited upper and lower limits)
Chromium (Cr): 8.0%~9.5%
Molybdenum (Mo): 0.85% ~ 1.05%
Vanadium (V): 0.18% ~ 0.25
Niobium (Nb) : 0.06%~0.10%
Nitrogen (N): 0.030% ~ 0.070%
Impurity control: sulfur (S), phosphorus (P) content is very low (≤ 0.040%).
III. Performance Characteristics
High temperature performance:
Long-term use temperature can reach 580℃~600℃, with excellent thermal strength and oxidation resistance.
Anti-temperature relaxation performance is better than traditional 9Cr-1Mo steel.
Mechanical properties:
Tensile strength ≥585 MPa, yield strength ≥415 MPa.
Corrosion resistance: suitable for the environment containing sulfur, chlorine and other corrosive media.
Fourth, the application areas
Power industry: boiler superheater, reheater and water-cooled wall pipe.
Nuclear power and chemical industry: high-temperature and high-pressure pipes and reactor components
Aerospace: high temperature resistant structural parts.
V. Manufacturing process
Seamless steel pipe process: controlled rolling, controlled cooling technology, combined with fine crystallisation metallurgical treatment to improve uniformity and strength.
Surface treatment: usually bare or plated to meet the needs of different working conditions.
VI. Comparison with other materials
Difference with T9 steel: by adding V, Nb, N elements, refine the grain and improve high temperature stability.
Relationship with P91 steel: SA213 T91 and SA335 P91 are similar in composition, but T91 is special for boiler tubes and P91 is for pipelines.
Summary: SA213 T91 is a ferrite-martensitic heat-resistant alloy steel, high chromium, molybdenum-based and add trace alloying elements, designed for high-temperature and high-pressure environments, widely used in power, nuclear power and chemical industry, high-end equipment