| 摘要 |
<p>PURPOSE:To produce a hot rolled steel plate excellent in hydrogen induced cracking resistance by finishing the hot rolling of a continuously cast slab of specific composition at specific temp. and then subjecting the resulting plate to coiling at specific temp. and then to air cooling. CONSTITUTION:The steel has a composition consisting of, by mass, 0.02-0.20% C, 0.01-0.50% Si, <=0.80% Mn, <=0.02% P, <=0.0020% S, 0.01-0.10% Al, 0.0005-0.0060% Ca, and the balance essentially Fe with inevitable impurities. A continuously cast slab of the steel is heated up to the prescribed temp., and hot rolling is finished at a temp. between (Ar3+50 deg.C) and (Ar3-30 deg.C). Then coiling is done at 500-650 deg.C, followed by air cooling. One or more elements among Cr, Mo, Cu, Ni, Ti, Nb, V, etc., are further incorporated into the steel. By this method, this steel can remarkably contribute to the improvement of the quality of a welded steel pipe for line pipe for transporting natural gas containing hydrogen sulfide and crude oil.</p> |
