ELECTRON-BEAM WELDED JOINT, STEEL MATERIAL FOR ELECTRON-BEAM WELDING, AND MANUFACTURING METHOD THEREFOR

摘要

A steel for electron-beam welding according to the present invention includes at least C: 0.02% to 0.10%, Si: 0.03% to 0.30%, Mn: 1.5% to 2.5%, Ti: 0.005% to 0.015%, N: 0.0020% to 0.0060%, and O: 0.0010% to 0.0035%, further includes S: limited to 0.010% or less, P: limited to 0.015% or less, and Al: limited to 0.004% or less, with a balance including iron and inevitable impurities. An index value CeEBB obtained by substituting composition of the steel into following Formula 1 falls in the range of 0.42 to 0.65%, the number of oxide having an equivalent circle diameter of 1.0 µm or more is 20 pieces/mm 2 or less at a thickness center portion in cross section along the thickness direction of the steel, and the number of oxide containing Ti of 10% or more and having an equivalent circle diameter of not less than 0.05 µm or more and less than 0.5 µm falls in the range of 1 × 10 3 to 1 × 10 5 pieces/mm 2 at the thickness center