HIGH STRENGTH STEEL PIPE OF UOE TYPE WITH GREAT DEFORMABILITY AND SHOCK VISCOSITY AT LOW TEMPERATURES IN THE WELD OF TERMAL INFLUENCE ON WELDING

摘要

1. Steel pipe type UOE, characterized in that it has a steel composition containing mainly 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 - not more than 0.020%; S - not more than 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 - not more than 0.0070%; Al is at least 0.005 and not more than 0.060%, the rest being Fe and inevitable impurities, while the hardenability index Pcm described by equation (1) is not more than 0.22%, the ratio Cu + Cr + Ni is at least 0.4 and not more than 1.5%, and the ratio of Nb + Mo + V is not more than 0.05%, while the steel has a yield strength of at least 480 MPa, the ratio of yield strength to tensile strength in the longitudinal direction is not more than 85% and the impact energy absorbed by the test sample when testing samples according to Charpy in the HAZ at - 40 ° C, at least 40 J:! Pcm = C + (Si / 30) + (Ni / 60) + (Mo / 15) + {(Cr + Mn + Cu) / 20} + (V / 10) + 5B. (one) ! 2. The steel pipe according to claim 1, additionally containing not more than 0.10% Cr by weight.