Method of producing steel for steel pipe excellent in...

Details Method of producing steel for steel pipe excellent in... Method of producing steel for steel pipe excellent in...

2011-06-14

2011-06-14

Wyszomierski, George (Department: 1733)

Specialized metallurgical processes, compositions for use therei

Processes

Producing or treating free metal

C075S548000, C075S512000, C075S558000, C420S590000

Reexamination Certificate

active

07959709

ABSTRACT:
A method of producing steel pipe excellent in sour-resistance performance, uses comprises controlling the amount of Ca addition charged into molten steel in a ladle according to a N content in the molten steel prior to Ca addition. As a result of the controlling step, a CaO content in the inclusions is in the range of 30 to 80%, the ratio of the N content in the steel to the CaO content in the inclusions satisfies the relation expressed by equation (1), and a CaS content in the inclusions satisfies the relation expressed by equation (2).in-line-formulae description="In-line Formulae" end="lead"?0.28≦[N]/(% CaO)≦2.0  (1)in-line-formulae description="In-line Formulae" end="tail"?in-line-formulae description="In-line Formulae" end="lead"?(% CaS)≦25%  (2)in-line-formulae description="In-line Formulae" end="tail"?where [N] represents the mass content (ppm) of N in the steel, (% CaO) represents the mass content (%) of CaO in the inclusions, and (% CaS) represents the mass content (%) of CaS in the inclusions.

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