SEAMLESS PIPE OF MARTENSITE STAINLESS STEEL FOR OIL FIELD PIPE EQUIPMENT AND PROCEDURE FOR ITS MANUFACTURE Russian patent published in 2011 - IPC C22C38/58 C22C38/40 C21D9/08 

FIELD: metallurgy.

SUBSTANCE: here is disclosed seamless pipe of stainless steel containing wt %: less, than 0.010% of C, 1.0% or less of Si, from 0.1 to 2.0% of Mn, 0.020% or less of P, 0.010% or less of S, 0.10% or less of Al, from 10 to 14% of Cr, from 0.1 to 4.0% of Ni, 0.05% or less of N, and also, if necessary, one or more of: Cu 2.0 wt % or less, Mo 2.0 wt % or less, V 0.1% or less, Nb 0.1% or less, and Ti 0.1% or less, the rest - Fe and unavoidable impurities Pipes are quenched for martensite and are tempered. At quenching after heating to temperature equal or higher, than temperature of transition of Ac₃, pipes are cooled to temperature within ranges from 100°C and below at rate of cooling equal or higher, than rate of cooling in air Pipes are tempered at temperature from over 450°C to 550°C and successively cooled.

EFFECT: seamless pipe simultaneously possesses high strength by yield point and raised low temperature impact strength.

8 cl, 1 dwg, 3 tbl, 1 ex