Abstract: An I-beam is made lighter in weight by corrugating the central portion of its web. Dimension of the corrugating is determined by predetermined experimental equations. The corrugating work is performed by a pair of complementary intermeshing rolls having the same dimensions.

Abstract: Strong and tough steel is prepared by heating to a temperature of 800.degree. - 1000.degree. C., preferably from 800.degree. to 950.degree. C., before the rolling step, finish rolling at temperatures within the range of from 680.degree. to 850.degree. C., preferably from 680.degree. to 800.degree. C. and with a reduction ratio in thickness of not less than 30% based on the plate thickness of the steel when the finish rolling is started. It is advantageous to provide for a pretreatment of the steel, said pretreatment including the steps of initially heating the steel to a temperature higher than 1000.degree. C., rolling the heated steel to a suitable intermediate thickness and cooling the rolled steel to a temperature lower than 650.degree. C.Tempering may also be carried out at a temperature of 500.degree. - 650.degree. C. for 20 minutes -- 2 hours.

Abstract: A heating roller apparatus with precise temperature measurement is disclosed which has a rotatable roller member comprising a cylindrical wall defining a room in the inside thereof and an annular groove therein, a heat source means, such as electrically excited induction coils, for heating the cylindrical wall, and a temperature sensor stationarily positioned in the annular groove of the cylindrical wall for measuring a temperature of the cylindrical wall of the roller member. The annular groove has an opening on the outer surface of the cylindrical wall, and two adjacent circumferentially extending wall faces which penetrate into the cylindrical wall in the direction substantially perpendicular to the rotating axis of the rotatable roller member. The annular groove is located at a part of the cylindrical wall adjacent to the end face of the roller member so that the outer surface of the remaining part of the cylindrical wall operates as a heat treating working surface.