Abstract: A method for manufacturing a seamless pipe, comprises:preparing a billet made of an alloy steel or an alloy;joining a steel plate to an end surface at which piercing of the billet is commenced;preparing a piercing plug made of Mo, a Mo alloy or a heat-resisting steel;hot-piercing the billet by using the piercing plug to produce a hollow shell; androlling the hollow shell to produce a seamless pipe.

Abstract: A method for manufacturing a seamless pipe, comprises:preparing a billet made of an alloy steel or an alloy;joining a steel plate to an end surface at which piercing of the billet is commenced;preparing a piercing plug made of Mo, a Mo alloy or a heat-resisting steel;hot-piercing the billet by using the piercing plug to produce a hollow shell; androlling the hollow shell to produce a seamless pipe.

Abstract: The present invention relates to a process for making non-oriented high Si steel sheet without problems during the sequence from the step of making molten steel to the step of rolling to final sheet thickness. An ingot (or a continuously cast piece) of high Si steel (containing 4.0 to 7.0% Si and specified with Al, Mn, C and P) is subjected to slabbing-hot rolling (or else directly slab rolling-hot rolling) and subsequently the hot rolled steel is reduced to thin thickness. The steel material is maintained at temperature of more than a determined temperature from the step of making molten steel to the step of hot rolling. In the step of hot rolling, information regarding finish rolling conditions and coiling conditions is used to provide structure suitable for the subsequent thin rolling. The hot rolled steel is then warm-rolled to the required thickness.

Abstract: A method for automatically controlling the width of a slab during hot rough-rolling thereof, which comprises: arranging a pair of horizontal broadening rolls each having at least one annular projection in a hot roughing mill train comprising a plurality of roll stands; calculating an amount of roll gap correction of said pair of broadening rolls on the basis of the variation in the width of said slab during hot rough-rolling on said hot roughing mill at the entry of said pair of broadening rolls; and, controlling the roll gap of said pair of broadening rolls in response to said amount of roll gap correction; thereby automatically controlling the width of said slab during hot rough-rolling thereof to a prescribed value at a high accuracy in accordance with the finishing width of a steel strip, and at the same time, automatically correcting variations in the width of said slab during hot rough-rolling thereof at a high accuracy.