HIGH-STRENGTH STEEL PIPE OF UOE TYPE WITH GREAT DEFORMABILITY AND IMPACT STRENGTH AT LOW TEMPERATURES IN AREA OF THERMAL EXPOSURE IN PROCESS OF WELDING Russian patent published in 2012 - IPC C22C38/58 

FIELD: metallurgy.

SUBSTANCE: pipe is produced from steel containing the following, wt %: C: at least 0.03 and not more than 0.07; Si: at least 0.05 and not more than 0.50; Mn: at least 1.6 and not more than 2.2; P: at least 0.020, S: at least 0.003, Cu: at least 0.20 and not more than 0.60; Ni: at least 0.20 and not more than 0.80; Nb: at least 0.005 and not more than 0.030; Ti: at least 0.005 and not more than 0.030; N: at least 0.0070, Al: at least 0.005 and not more than 0.060, not more than 0.1 Cr, besides the balance is Fe and unavoidable admixtures including B, Mo of not more than 0.02 and V of not more than 0.01. Steel has hardening capacity index Pcm, making not more than 0.22%, the ratio Cu+Cr+Ni, making from 0.4% to not more than 1.5%, ratio Nb+Mo+V, making not more than 0.05%, yield point of at least 480 MPa, ratio of yield point to strength limit in longitudinal direction of not more than 85%, and impact energy absorbed by a tested sample when testing samples by Charpy in a heat affected zone at - 40°C, at least of 40 J.

EFFECT: steel has high deformability and impact strength at lower temperature in a heat affected zone.

2 cl, 3 dwg, 1 tbl, 1 ex