Nippon Steel Corporation

Shozo Mizoguchi

Yoshiyuki Ueshima

Takashi Sawai

Masamitsu Wakoh

Tooru Matsumiya

Masao Fuji

Hidetoshi Yuyama

Nobuyuki Komatsu

Taketo Nakano

Continuous-cast slab and steel product having dispersed fine particles

MnS is finely dispersed and precipitated in a steel, and the steel obtained has highly improved characteristics such as HAZ toughness, cold cracking resistance, and corrosion resistance. This steel is obtained by continuously casting a component-adjusted molten steel having a dissolved oxygen concentration of 20 to 60 ppm and containing 0.01 to 0.05% by weight of a deoxidizing element, at a specific cooling rate.

Process for preparation of a casting having MnS dispersed and uniformly

In a method for controlling solidification segregation in casting of carbon steel containing 0.53 wt. % or less of carbon, .alpha.-phase stabilizing elements and .gamma.-phase stabilizing elements of the carbon steel are separated from each other at inter-dendritic portions by adding 2 wt. % or less of at least one element selected from the group consisting of Be, Cr, Nb, Sn, Ti, Mo, and V into the molten steel.

Method for controlling solidification segregation of steel

The .alpha.-stabilizing element, e.g. P, and the .gamma.-stabilizing element, e.g. Mn, do not segregate at an identical site of a casting. Castings are cooled at a rate of 40.degree. C./min or less in a temperature range of the peritectic reaction and/or the Ar.sub.4 transformation, thereby condensing P and Mn into .delta. and .gamma. phases, respectively.

Method for mitigating solidification segregation of steel

In a method for continuous casting of steel, an improvement which is constituted by carrying out the continuous casting process while the thickness of a molten mold powder pool adjacent to the molten steel melt within a continuous casting mold is maintained at a desired preset value, and whenever the actual value deviates from the preset value, the continuous casting can still be continued by adjusting the casting conditions or by selecting a powder appropriate for the casting conditions. The method produces a casting requiring no subsequent processing to remove defects.

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Kawasaki, Japan

Shozo Mizoguchi