As-rolled steel plate having improved low temperature toughness and production thereof

摘要

A high strength steel plate of improved low temperature toughness useful for making an arctic grade line pipe is provided with the addition of 0.8 - 2.0% by weight of Ni and 0.0005 - 0.0040% by weight of Ca, which may be used in the as-rolled state and manufactured through two step controlled rolling the secondary step rolling of which is carried out at a temperature lower than a conventional rolling temperature.