T91 steel pipe

T91 steel pipe is a kind of steel pipe. T91 steel is a new type of martensitic heat-resistant steel jointly developed by the National Oak Ridge Laboratory of the United States and the Metallurgical Materials Laboratory of the American Combustion Engineering Corporation. It reduces the carbon content on the basis of 9Cr1MoV steel, strictly limits the content of sulfur and phosphorus, and adds a small amount of vanadium and niobium elements for alloying.

The German steel number corresponding to T91 steel is X10CrMoVNNb91, the Japanese steel number is HCM95, and the French steel number is TUZ10CDVNb0901.

Chemical composition % of T91 steel pipe:

C	Mn	P	S	Si	Cr	Mo	V	Nb	N	Ni
0.08-0.12	0.30-0.60	≤0.02	≤0.01	0.20-0.50	8.00-9.50	0.85-1.05	0.18-0.25	0.06-0.10	0.03-0.07	≤0.40

T91 steel pipe mechanical properties:
Tensile strength ≥ 585 MPa,
Yield strength ≥ 415 MPa,
Hardness≤250 HB,
Elongation (standard circular sample with a gauge length of 50 mm) ≥ 20%,
Allowable stress value [σ]650℃=30 MPa.

T91 steel pipe heat treatment process:
The final heat treatment of T91 is normalizing + high temperature tempering, the normalizing temperature is 1040°C, the holding time is not less than 10 minutes, the tempering temperature is 730-780°C, the holding time is not less than 1h, the structure after the final heat treatment is tempered fire martensite.

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