Nippon Steel Corporation

Koe Nakajima

Toshio Kikuma

Tsuyoshi Kawano

Kazuo Watanabe

Hiromi Matsumoto

Yoshikazu Matsumura

Yuji Uehori

Shiroh Sanagi

Hideki Tokita

Wataru Midzutani

Shigeru Ogawa

Hiroshi Katoh

Yasumitsu Onoe

Minoru Kawaharada

Hiroshi Yada

Yoshun Yamamoto

Takashi Haji

Akira Matsufuji

Matsuo Ataka

Yukio Noguchi

Koshiro Aoyagi

Shozo Sekino

Seiichi Sasahira

Yoshikazu Haneda

Akira Ohnuki

Hiroyasu Yamamoto

Keitaku Ondo

Hiromi Matumoto

A cold rolled boron steel sheet having excellent stretchability, deep drawability, and second workability and method for producing the same, which comprises the steps of hot rolling a steel containing not more than 0.05% C by weight and, P and N in the relation of P+5N.ltoreq.0.0175% by weight at a temperature of 850.degree. C. or more, cold rolling the hot rolled steel strip at a reduction of not less than 50%, and subjecting the cold rolled steel strip to continuous annealing at a temperature between the recrystallization temperature and the A.sub.3 point.

Cold rolled steel sheet having excellent press formability and method

A cold rolled steel sheet having excellent stretchability, deep drawability, and secondary workability, and a method for producing the same, which comprises the steps of hot rolling an Al-killed steel containing not more than 0.0025%N by weight, not more than 0.010%P by weight, and not more than 0.07% C by weight, and wherein P and N have the relation of P+5N.ltoreq.0.02% by weight, at a temperature of 850.degree. C. or more, cold rolling the hot rolled steel strip at a reduction of not less than 50%, and subjecting the cold rolled steel strip to continuous annealing at a temperature between the recrystallization temperature and the A.sub.3 point.

Bars and wire rods are rolled from billets or blooms in the disclosed process which includes a primary rolling step resulting in an intermediate material, a secondary rolling step and a heat treatment. The primary (first) rolling step includes rolling the billet or bloom steel material into an intermediate material at a mass flow rate to enable it to be maintained during the primary rolling within a temperature range corresponding to a predetermined deformation resistance level of the steel material. This predetermined deformation resistance level is selected so as to take advantage of an opportunity to save energy. The intermediate material resulting from primary rolling is coiled and its temperature is adjusted so as to maintain the intermediate material at a desired starting temperature for the secondary rolling step. The desired starting temperature for secondary rolling is related to a desired starting temperature for the heat treatment following the secondary rolling enabling heat treatment to be carried out in line.

Reduced energy consumption method for rolling bars or wire rods

A novel hot-rolled ferritic steel composed of 70% or more of equiaxed ferrite grains having an ultra-fine grain size of 4 .mu.m or less. This steel is produced by a hot working at approximately the Ar.sub.3 point and by one or more passes of the hot working having a total reduction ratio of at least 75%. When a plurality of passes is carried out, the time between passes is less than one second. Due to hot working, dynamic transformation of austenite and/or dynamic recrystallization of ferrite takes place. The total reduction ratio may be at least 35% for a high purity steel.

Ferritic steel having ultra-fine grains and a method for producing the

In making metal sections, starting material having a quadrangular cross-section is hot-forged into a blank resembling the desired product in cross-section, and the length of the piece is divided into sections of a given length. Then, the blank is hot-rolled into the product having the desired cross-section.

Method and apparatus for manufacturing metal sections

Three or more work rolls are arranged substantially in line with each other so that the adjoining work rolls each form a roll pass between them. The work rolls are driven in such a way that the rolls closer to the exit end of the rolling mill stand rotate with increasingly greater peripheral speeds. Metal strip is continuously passed through each roll pass and is wound around part of the periphery of the work rolls disposed between the work rolls at both ends of the stand. Thus, the strip is rolled between each pair of the adjoining work rolls. The work rolls are also driven in such a way that at least in one of the pairs of the work rolls, the peripheral speed of the higher-speed work roll is greater than the speed with which the strip leaves the roll pass formed by the pair of work rolls.

Method of rolling metal strip

A rolling mill includes at least one roll carrying a sleeve loosely on the barrel. The sleeve is inclined slightly by applying radially inward forces at two spaced positions along the outer peripheral surface of the sleeve to displace or to restrict displacement of the sleeve in the axial direction. The force applying points are independent of rotational direction of the sleeve, so that only one unit is needed even where there is reverse rotation. By controlling the relative value between the two forces, the mill can be given a powerful crown controlling capacity for workpieces of varying width, and the sleeve guiding unit is sufficiently durable to withstand high speed rolling during mass production.

Method of setting axial position of loosely carried sleeve in a rolling

A rolling mill includes at least one roll carrying a sleeve loosely on the barrel, and a sleeve-supporting-and-guiding unit the restricting point of which, i.e. the point at which force for axially shifting or restricting the shifting of the sleeve is applied on the sleeve, is located somewhere along the second-half semi-circular portion of the sleeve as viewed in the rotational direction of a complete turn of the sleeve ending at the loading point where the sleeve and the associated roll are subjected to loading pressure. The mill has a powerful crown-controlling capacity for workpieces varying widths, and the sleeve-supporting-and-guiding unit is sufficiently durable to withstand high speed rolling for mass production.

Rolling mill with loosely sleeved roll

An apparatus for controlling axial positions of rolls of a rolling mill to obtain and maintain desired axial rigidity of the rolls. Pre-stress, the axial load and the axial position of each roll are detected. The detected signals are processed to determine the axial positions of the rolls to achieve the desired rigidity.

Apparatus for controlling the position of roll in the direction of the

A method and apparatus for manufacturing metal pipe. The edges of a metal plate are bent up slightly, and the thus bent plate is then bent into a U-shape cross-section blank. The U-shape blank is finish-formed into an O-shaped blank with the longitudinal edges opposed to each other in a position for welding by placing one end of the U-shaped blank into at least one two-part die the parts of which are movable toward and away from each other. The die has at least one portion with the shape of the opposed die recesses defining a reforming area on one end of the die portion which has an O-shaped cross-section, a finish forming area in the middle of the length of the die portion having an O-shaped cross-section, these O-shaped cross-sections being the shape of the O-shaped blank, and a transitional area at the other end of the die portion having a cross-sectional shape which changes gradually from an O-shape adjacent the finish forming area to an oval shape elongated in the direction of movement of the die parts at the other end of the die portion. The transitional area is relatively short as compared to the remainder of the die parts. This one die portion is shorter than the length of the blank. The U-shaped blank is placed in the die with the elongated dimension of the cross-section corresponding to the elongated dimension of the oval shape and with one end of the blank at the one end of the die portion, and the two part die is closed for shaping the U-shaped blank into a blank having an O-shaped cross-section reformed portion on said one end of the blank, a finished O-shaped cross-section and a transitional section. The two part die is opened and the thus formed blank along the die until the edge of the transitional section of the blank is at the end of the finished forming area of the die portion adjacent the reforming area. The steps of positioning the blank and opening and closing the die are repeated until the blank is completely formed into an O-shaped cross-section, and the opposed edges of the plate are then welded to produce the O-shaped cross-section blank.

Method and apparatus for manufacturing metal pipe

In a method and an apparatus for manufacturing a metal pipe wherein a flat strip or skelp is formed into a cylindrical pipe while being fed in its longitudinal direction by a forming mill having a prefinishing stand, a train of forming stands for forming the skelp with a U-shaped cross section, and a train of finishing stands, the improvement wherein both edge surfaces of the skelp are caused to contact in substantially point contact recess-defining surfaces of concave V-shaped recess in pairs of forming rolls, the respective rolls which are disposed symmetrically in a plane normal to the pass line as the skelp moves through the train of forming stands along the line, and the skelp has a bending load applied by the forming rolls so as to form the skelp into a U-shaped skelp. According to this method and apparatus, there is no need to change the forming rolls even if the diameter or wall thickness of the pipe to be manufactured are changed, and also since the skelp edge is held, during the forming process, at positions in a plane normal to the pass direction by the surfaces of the concave recesses, the skelp is not twisted around the pass line so that threading of the forming mill can be carried out accurately and easily.

Method and apparatus for manufacturing metallic pipe

This invention relates to a straightening mill for section steel, such as I-beams, channel steel, etc., particularly to a straightening mill for section steel, wherein as the section steel is straightened so called 'end crook' at the tail end thereof is eliminated. The section steel is passed through a straightening mill which comprises a plurality of driving rollers and a plurality of driven rollers defining a pass line therebetween. The axes of the driving and driven rollers are staggered and, except for the first driving roller, each of the driving rollers is fixed relative to the pass line. The driven rollers are adjustable and by proper adjustment of the first driving roller relative to the pass line, end crook is reduced or eliminated.

Straightening mill for section steel

A process for producing a steel having excellent strength and toughness, which comprises continuously casting a molten steel containing 0.01 - 0.10% Al and 0.002 - 0.009% N with an average cooling rate of not lower than 3.degree. C/min. down to 500.degree. C to obtain a steel slab heating the steel slab to a temperature ranging from 900.degree. to 1150.degree. C and rolling the steel slab.

Process for producing a steel having excellent strength and toughness

A process for hot rolling an H-shaped metallic material from a workpiece of rectangular cross section which comprises reducing the workpiece in the width direction thereof while wedgewise knifing the opposing sides of the workpiece by means of a first pair of grooves formed in rolls of a vertical roll stand; reducing the workpiece in the width direction thereof while spreading the knifed sides by means of a second pair of grooves which may be formed in rolls of another vertical roll stand or in the rolls having said first pair of grooves; and subsequently rolling the workpiece to a required size by universal rolling mills. This process thus enables a starting material of a rectangular cross section to be employed instead of that of H-shaped cross section.

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Nakama, Japan

Koe Nakajima