FIELD: metallurgy.
SUBSTANCE: steel material used for the manufacture of seamless pipes operating in contact with a medium containing hydrogen sulfide and gaseous carbon dioxide. The steel material has a chemical composition containing, wt.%: С: 0.035 or less, Si: 1.00 or less, Mn: 1.00 or less, P: 0.030 or less, S: 0.0050 or less, sol. Al: 0.005 to 0.100, N: 0.001 to 0.020, Ni: 5.00 to 7.00, Cr: 10.00 to 14.00, Cu: 1.50 to 3.50, Mo: from 1.00 to 4.00, V: 0.01 to 1.00, Ti: 0.02 to 0.30, Co: 0.01 to 0.50, Ca: 0.0003 to 0, 0030, O: 0.0050 or less, W: 0 to 1.50, Nb: 0 to 0.50, B: 0 to 0.0050, Mg: 0 to 0.0050, rare earth metals (REM): 0 up to 0.020, the rest is Fe and inevitable impurities. Among the inclusions present in the steel material, the total concentration of Mn sulfide particles having a Mn content of 10% or more and an S content of 10% or more, and having an equivalent circle diameter of 1.0 µm or more, and Ca sulfide particles having a calcium content of 20% or more and a sulfur content of 10% or more and an equivalent twist diameter of 2.0 μm or more is 0.50 particles/mm 2 or less.
EFFECT: steel material has high resistance to sulfide stress corrosive effect.
8 cl, 3 tbl, 2 ex
