Thick high tensile steel sheet excellent in weldability and its manufacturing method

文件类型：PDF文档
文件大小：247K
PROBLEM TO BE SOLVED : To provide a high tensile strength thick steel plate having excellent weldability and tensile strength in a class of 780 MPa, and to provide its production method. ŽSOLUTION : The high tensile strength thick steel plate has a composition in which the content of C is reduced to 0.06 to 0.09% and the contents of Si, Al, P, S and N are controlled to proper ones, and compositely comprising 1.8 to 2.5% Mn, 0.03 to 0.08% Nb, 0.008 to 0.020% Ti and 0.0005 to 0.0025% B, and satisfying the Pcm of ≤0.22. The steel plate may comprise one or more kinds selected from ≤0.2% Cu, ≤0.3% Ni, ≤0.5% Cr, ≤0.04% Mo and ≤0.08% V, and may comprise one or two kinds selected from Ca and rare earth metals as well. In this way, the high tensile strength steel plate has a tensile strength of ≥780 MPa, excellent weldability and excellent surface quality. ŽCOPYRIGHT : (C)2007, JPO&INPIT Ž