To provide a method for producing a martensitic stainless steel tube having high strength of >650 MPa yield stress and having excellent low temp. toughness.
Martensitic stainless steel having a compsn. contg., by weight, 0.15 to 0.22% C, ≤0.5% Si, 0.1 to 1.5% Mn, <0.008% P, ≤0.005% S, 12 to 14% Cr, ≤0.3% Al and 0.001 to 0.08% N, furthermore contg., at need, one or ≥ two kinds among 0.05 to 0.5% Ni, 0.05 to 0.5% Mo, 0.05 to 0.5% Cu, 0.001 to 0.05% Ti and 0.001 to 0.01% Ca, and the balance Fe with inevitable impurities is made a tube by a hot rolling method, which is thereafter heated to a temp. region of the Ac3 to 950°C, is succesively cooled to a room temp. at a rate of air cooling or above and is subsequently subjected to tempering treatment at ≤Ac1 point.
SAKAMOTO TOSHIHARU
MARUYAMA KAZUSHI
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