Republic Steel Corporation

Dionisyj W Demianczuk

Joseph E Franklin

Gregory J McLean

George M Waid

John K Abraham

Cecil B Griffith

Jerry D Thomas

Clifford E Rowden

Carl J Bingel

Steel products having high strength or good drawing or magnetic or electrical properties, requiring levels of carbon or manganese, or both, that are too high to allow rimming action are produced to have the desired properties, in effect, but with a surface condition characteristic of rimmed steel. The method involves pouring an ingot mold 80 to 95% full of molten, rimming steel, then allowing the steel to stand and rim for several minutes while a shell freezes against the mold wall, and thereafter filling the mold while inserting into the molten steel stream additional carbon or manganese, plus any other elements such as P, Al, Cb, V, Cr, Ni, Si or others, so that the core of the ultimately solidified ingot is steel having the above-desired strength or other properties. An integral shell or skin of rimmed steel, essentially all ferrite, covers the principal surface of the ingot, and likewise of slab, plate, and hot rolled and cold rolled strip or the like that may be derived from the ingot, thereby affording products which are in effect of the desired internal composition but have the superior surface condition of rimmed steel.

Production of steel products with medium to high contents of carbon and

For skelp to make pipe having a seam butt-joined as by electrical resistance or submerged arc welding, skelp is made by pouring a base melt of rimming steel into an ingot mold to about 80 to 95% full and then after a shell of rimmed steel has solidified against the mold wall, completing pouring of the same melt while adding further material to the molten core, e.g. more C or Mn, and Al or the like for killing, so that the solidified ingot has a core of desired high strength, killed or semi-killed steel. The ingot is processed to desired skelp by hot rolling, the top and bottom regions being suitably cropped, so that the skelp has a main body of the high strength steel, bordered lengthwise by integral edge zones, e.g. 1/2 inch or more wide, of the rimmed steel, free of unwanted inclusions. When rolled to pipe shape, with finished edges, the edge zones are electrically butt welded, such operation being effected with unusual facility. In the completed pipe, the weld region is relatively free of oxide or like inclusions, and thus not susceptible of rejection for defects at or about the seam, while the pipe is essentially characterized by high wall strength.

Manufacture of electrically welded steel pipe

High strength, low alloy steel is produced, preferably as a hot rolled article (e.g. strip), to have a rimmed skin of essentially ferrite while having a main body or core which is aluminum-killed and comprises, for superior mechanical properties including yield strength, a suitable quantity of columbium and/or vanadium. The carbon, manganese and sulfur contents of the base metal, which provides the skin and plus the addition, the core, are preferably limited to provide special results as low alloy steel and also, by the same limitations, to provide auto sulfide shape control and thus to avoid unwanted directionality regarding toughness and bendability. The steel is made by pouring a mold 80-95% full of the base composition, then allowing the steel to rim for several minutes, and after a shell has solidified, continuing to pour while adding Al and Cb or V to the teemed stream, thereby providing an ingot with the above killed core, which can be hot reduced as desired.

High strength, low alloy steel with improved surface and mechanical

Steels such as standard carbon or alloy types that have too much carbon, i.e. 0.15% or (notably) more, to be rimmed, are produced in improved form by pouring a base melt of such steel which includes manganese up to 1.75% and other alloying elements if desired, and is sufficiently deoxidized, as with Si or Al, to be partially killed but not fully killed. Such pouring in an ingot mold is initially up to 80 to 95% full, under circumstances such that a shell solidifies, and pouring is continued, while adding into the still-molten core sufficient aluminum at least to kill the core and also as desired, other alloying or useful elements. The solidified ingot ultimately yields hot rolled bar products which are essentially aluminum-killed steel but have a partially killed skin and have superior surface conditions lacking blow holes, and being very appropriate for bar stock.

Steel products such as bars, compositionally non-rimming and internally

A rimmed steel product, in as-hot-rolled, or cold rolled and annealed form, is made essentially non-aging by inclusion of one or both of the aging-retardant elements vanadium and boron, while retaining an excellent, clear surface that is not adversely affected by the presence of such element or elements. To produce such articles, an ingot mold is poured 80 to 95% full of plain rimming steel, and the molten steel is allowed to rim, e.g. for several minutes, until a rimmed shell solidifies against the mold wall. Then pouring is completed with the same steel, while adding one or both of the aging-retardant elements to the teemed stream. Processed like rimmed steel, ultimate rolled (e.g. strip) products having a thin, truly rimmed skin over a main body of substantially non-aging steel, are found to exhibit no unwanted change of properties (e.g. as would be revealed by significant strain lines) such as usually characterizes the effect of aging in rimmed steel. There is some advantage in using the two elements together, or in the simultaneous inclusion of other, strength-promoting elements such as Cb, Zr, Si, and it has been noted that tensile properties are enhanced when V is added, as above, for aging-retardant function.

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Parma, OH, United States of America

Dionisyj W Demianczuk