Abstract: 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.

Abstract: In a method for roll forming a flat metal strip through a roll forming machine into a round tubular product while the metal strip is being lengthwise fed therethrough, an improved method wherein regions of a specified width extending inward from the edges of said strip are imparted with substantially zero curvature. The tube forming method prevents decrease in the wall thicknesses at the edges when used in the manufacture of a thick walled electric welded pipe, and prevents the occurrence of edge buckling and springback when used in the manufacture of thick walled pipe so that in either case a proper and satisfactory butt junction for subsequent welding can be obtained.

Abstract: A metal workpiece is rolled in a rolling mill, including an upstream rolling stand or pinch rolls and more than one stream rolling stand. The roll gaps of the workrolls of the downstream rolling stand are set so that the eqivalent contact angle .theta.e (.theta.e=tan.sup.-1 (cos .alpha..times.tan .theta.) wherein .theta. denotes the contact angle between the workrolls in the bottom of the roll groove and the workpiece and .alpha. denotes the inclined angle of the groove) is larger than tan.sup.-1 .mu. (.mu. denotes a coefficient of friction between the workpiece and the workrolls at the time of biting therebetween and also is smaller than tan.sup.-1 .mu.' (.mu.' denotes a coefficient of friction between the workpiece and the workrolls when the workpiece is completely bitten between the workrolls and the rolling operation is in progress).