| 摘要 |
PURPOSE:To manufacture the titled seamless pipe excellent in toughness and sulfide stress cracking resistance without causing deterioration in strength, by subjecting a martensitic stainless steel billet to hot piercing rolling and by successively applying working, cooling, and tempering to the above under specific conditions. CONSTITUTION:A martensitic stainless steel billet is subjected to piercing rolling in a temp. region of about 1,050-1,250 deg.C and then worked in an unrecrystallization temp. region (about 950 deg.C) at >=5% draft. After the conclusion of working, cooling is applied, without delay, down to 500 deg.C to 50 deg.C/min cooling rate to carry out hardening, so that a structure >=80vol.% of which is martensitic is formed. Subsequently, tempering is applied at a temp. of Ac1 point or below so as to manufacture a seamless pipe.
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