Abstract: An object of the present invention is to provide a lightweight strengthening member for an automobile, excellent in crush resistance in the axial direction and having high flexural strength. Further, another object thereof is to provide a strengthening member which does not generating cracks even when a high-strength steel sheet is used.

Abstract: An object of the present invention is to provide a lightweight strengthening member for an automobile, excellent in crush resistance in the axial direction and having high flexural strength. Further, another object thereof is to provide a strengthening member which does not generating cracks even when a high-strength steel sheet is used.

Abstract: The present invention is to provide a forming method and forming stand for forming a welded pipe of high dimensional accuracy on a welded pipe manufacturing line in which a metallic strip of a predetermined width is continuously formed by rolls and then welded, and more particularly the present invention is to provide a forming method and forming stand for forming both edge portions of the metallic strip with high accuracy. Positions of two pairs of upper and lower horizontal forming rolls or two upper horizontal forming rolls, the rolls being provided when the upper and lower horizontal rolls are divided into two with respect to the width direction of the metallic strip, can be adjusted in the width direction, and each divided upper roll can be turned and fixed on a vertical axis. Further, in order to exhibit the effect of the present invention at the maximum, the turning direction and turning angle of each upper roll is limited.

Abstract: An electric resistance welded steel pipe for machine structural use exhibiting excellent machinability comprises, in weight percent, 0.02-0.60% C, not more than 0.4% Si, 0.20-2.0% Mn, not more than 0.030% P, not more than 0.040% S, 0.001--0.030% T.Al, 0.0020-0.0100% N, not more than 0.0060% O, and one or both of not more than 0.040% Bi, not more than 0.040% Pb and not, Te and provided that the total amount of Bi and pb is not more than 0.050%, the remainder being Fe and unavoidable impurities. It may further comprise one or both of 0.10-1.50% Cr and 0.10-0.60% Mo and/or not more than 0.020% Ca, provided that Ca%/(1.25.times.0%+0.625.times.S%).gtoreq.0.05.