Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Itsuroh Hiroshige

Takuya Hara

Yukihisa Kuriyama

Yoshio Terada

Shinya Sakamoto

Takashi Motoyoshi

Hirotoshi Hishida

Takafumi Sebayashi

Yasuyuki Kuroda

Manabu Ueda

Electric resistance welded steel pipe excellent in deformability and fatigue properties after quenching which enables working into complicated shapes without spheroidization and which improves the fatigue properties after cold working and quenching without carburization are provided. The electric resistance welded steel pipe is characterized by containing, by mass %, C: 0.15 to 0.55%, Si: 0.01 to 0.30%, Mn: 0.5 to 1.5%, Ca: 0.0010 to 0.0030%, S: 0.0005 to 0.0050%, and O: 0.0005 to 0.0050%, having contents of Ca, O, and S satisfying 0.10&#x2266;[Ca](1&#x2212;124[O])/1.25[S]&#x2266;2.50, having Ca-based inclusions present at the base material and electric resistance weld zone with an average particle size of 1.0 to 10 &#x3bc;m and a density of 3 to 300/mm, and having a difference &#x394;Hv of the maximum hardness of the electric resistance weld zone and the average hardness of the base material part satisfying 100 to 500.

Electric resistance welded steel pipe excellent in deformability and fatigue properties after quenching

A production apparatus for a tapered steel pipe which holds the two ends of the steel pipe by shafts on carriers and moves it in the axial direction while rotating it to draw it to a taper by an intermediate working roll, wherein the shaft of the working roll is inclined 20 to 40 degrees with respect to the axis of the steel pipe and a roll caliber of the working roll is made an outwardly curved surface with little difference in roll peripheral speed; the face plate for mounting the working roll is positioned and supported with respect to the body by a hinge mechanism and is fastened to the body by fastening members; and the bearing of the working roll at the side close to the steel pipe is made smaller than the bearing at the side far from the steel pipe and the two bearings are connected by a tie-rod.

Apparatus and method for production of tapered steel pipe

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Tokyo, Japan

Itsuroh Hiroshige