The steel plate of high tensile strength, low acoustic anisotropy and high weldability and having a thickness of 30 mm to 100 mm and a voltage of 450 MPa or higher and flow limit of resistanceThe yield of 570 MPa or more in the region of the center of the thickness of the plate

摘要

High tension steel plate of low acoustic anisotropy and high weldability having an elastic limit of 450 MPa or greater and the limit of tensile strength of 570 MPa or greater.And process for producing the same.The present invention relates to a steel plate of high voltage low acoustic anisotropy and high weldability and elastic limit of 450 MPa or greater and the limit of tensile strength of 570 MPa or higher and a process for the production of steel plate are provided.The steel has a content of 0.10% or less, so obtaining a reason in the volume of the island of martensita of 3% or less, contains NB 242 0.025% and you 242 0005% so as to meet 0,045% 243 [NB] + 2 x [you] 243 0105%, containing Nb, Ti, C and N in the slots so that the value of a = ([NB] + 2 x [you]) x ([C] + [n] x (12 / 14) the 00055 00022.And has a steel structure where the right volume of bainite is 30% or more and reason in pearlita volume is less than 5%.