| 摘要 |
PURPOSE:To manufacture the titled steel pipe inexpensively by hot rolling steel contg. specified compsn. quantities of C, Mn, Si, Nb, V, Ti, B, etc., winding the plate at a low temp. to prepare seam welded steel pipe, then reheating and quenching the weld heat affected zone. CONSTITUTION:Steel composed of 0.08-0.26% C, 0.8-1.9% Mn, <=0.5% Si as basic components, >=one kind among <=0.05% Nb, <=0.05% V, <=0.03% Ti, <=0.0020% B and the balance Fe with inevitable impurity is hot rolled, then the plate is cooled rapidly to quench it, next wound at <=250 deg.C low temp. for maintaining the obtd. quenched fine grain structure. Thereafter, the hot rolled coil is formed, welded to seam welded steel pipe, then only seam welded zone where quenched structure is vanished by welding heat is reheated to >=900 deg.C, then the pipe is quenched, thereafter whole thereof is tempered. In this way, the seam welded steel pipe for oil well pipe superior in characteristics of collapse and sour resistance is obtd. with a low cost and a high yield without quenching the whole thereof.
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