Resistance welding of welded steel pipes possess excellent resistance to hydrogen induced cracking (HIC) and the low temperature toughness gets the resistance welding of welded joints, AND METHOD FOR ITS PRODUCTION

摘要

1. A steel pipe or tube, the resulting electric resistance welding, having a controlled chemical composition comprising, in mass%, C:. 0.03 to 0,59%, Si: 0.10 to 0,50%, Mn: from 0.40 to 2.10% and Al: 0.01 to 0.35%, the Si content and Mn content are such that the ratio of Mn / Si (mass) is in the range of from 6.0 to 9, 0, the balance being Fe and unavoidable impurities; wherein said steel pipe or tube has a rupture strength TS of not less than 434 MPa; and said steel pipe or tube comprises providing an electrical resistance welding the weld joint, wherein the total amount of silicon, manganese, aluminum, calcium, and chromium in the inclusions with an equivalent circle diameter 8 m or more is not more than 16 hr. / mn in wt.% relative to total weight of the weld width of 2 mm obtained by electric resistance welding, including iron base, wherein the weld joint obtained by electric resistance welding, have excellent HIC resistance and excellent Downhill vyazkost.2-temperature impact. . Steel pipe or tube, the resulting electric resistance welding according to claim 1, wherein the chemical composition further contains at least one element selected from Groups A, B, C or D, in wt%:. A: Ca: 0 0001 to 0,0040%; B: Cr: from 0,01 to 1,09%; C: one or more elements selected from Cu: 0.01 to 0.35%, Mo: 0.01 to 0 , 25%, Ni: 0.01 to 0.20% and B: 0.0001 to 0,0030%; D: one or more elements selected from Nb: 0.001 to 0,060%, V: 0.001 to 0.060% and Ti: 0.001 to 0.080% .3. A method for manufacturing a steel pipe or a steel pipe of electric resistance welding, comprising a continuous roll forming of hot rolled steel strip into an open pipe having an approximately circular cross-section, open tubes electric welding