HIGH TEST STEEL PIPE PRODUCED BY ELECTRICAL WELDING BY RESISTANCE METHOD AND METHOD OF MANUFACTURING THEREOF Russian patent published in 2018 - IPC C22C38/00 C21D8/10 C21D9/50 B21C37/08 C21D9/08 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, in particular to the creation of a high-strength steel pipe by electric resistance welding. Pipe is obtained by electric resistance welding from steel, wt. %: C 0.04–0.15, Si 0.10–0.50, Mn 1.0–2.2, P 0.050 or less, S 0.005 or less, Cr 0.2–1.0, Ti 0.005–0.030 and Al 0.010–0.050, the rest is Fe and unavoidable impurities, and a microstructure including a polygonal ferrite with a volume fraction of 70 % or more and a residual austenite with a volume fraction of 3–20 %, and a residue having at least one phase selected from martensite, bainite and perlite, wherein the polygonal ferrite has an average grain size of 5 mcm or more and a side ratio of 1.40 or less.

EFFECT: increased tear resistance and uniform elongation ensuring a suitable bendability of the steel pipe.

6 cl, 3 tbl