There is provided a steel pipe for pressure piping, the steel pipe being subjected to autofrettage. An average hardness of the steel pipe at its outer layer region is 1.20 times or more an average hardness of the steel pipe at its inner layer region. When an outer diameter of the steel pipe is denoted by D, and an inner diameter of the steel pipe is denoted by d, and when a measured value of a residual stress at an outer surface is denoted by σo1, a measured value of a residual stress at an outer surface after halving is denoted by σo2, and a measured value of a residual stress at an inner surface after the halving is denoted by σi2, an estimated value σi1 of a residual stress at the inner surface of the steel pipe that is determined by [σi1 = (-σi2) / (A×(t/T)2 - 1)], [t/T = ((σo2-σo1) / (A×(σo2-σo1) - C×σi2))1/2], [A = 3.9829 × exp(0.1071 × (D/d)2)], and [C = -3.3966 × exp(0.0452 × (D/d)2)] is -150 MPa or less.
PRESSURE PIPING STEEL PIPE AND STEEL PIPE MATERIAL
DRUCKROHRLEITUNGSSTAHLROHR UND STAHLROHRMATERIAL
TUYAU EN ACIER DE TUYAUTERIE SOUS PRESSION ET MATÉRIAU DE TUYAU EN ACIER
2024-07-31
Patent
Electronic Resource
English
IPC: | F16L PIPES , Rohre / B60R Fahrzeuge, Fahrzeugausstattung oder Fahrzeugteile, soweit nicht anderweitig vorgesehen , VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR / C21D Veränderung der physikalischen Struktur von Eisenmetallen , MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS / C22C Legierungen , ALLOYS / F02M Zuführen von Brennstoff-Luft-Gemischen oder deren Bestandteilen bei Brennkraftmaschinen allgemein , SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF |
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