| 摘要 |
The invention provides a thick steel plate, which is excellent in HAZ toughness during the large energy welding process. The characteristics of the thick steel plate satisfy the following chemical composition by mass% except oxygen constituent elements: Ti> 10%, A1<20%, 5 % <ca<40 % and 5 % <REM<50 %, 5 %<zr<40 % of at least any one of oxide, which satisfies the following formula (1) and (2). (1)Measured by an equivalent circle diameter gauge, the number of the oxide below 2 mu m is 200/mm < 2 > or more. (2) Measured by an equivalent circle diameter, the number of the oxide over 2 mu m is 100/mm < 2 > or less. |
