公开(公告)号：EP4428260A1

公开(公告)日：2024-09-11

申请号：EP22892427.0

申请日：2022-09-22

申请人： NIPPON STEEL CORPORATION

发明人： HIRATA, Kentarou ,  OKA, Masaharu ,  SAKAKI, Masahito ,  SAITO, Mamoru

IPC分类号： C22C38/00 ,  C21D9/46 ,  C22C38/14 ,  C22C38/32

CPC分类号： C22C38/00 ,  C22C38/32 ,  C22C38/14 ,  C21D9/46

摘要： A hot-rolled steel sheet which has excellent rigidity along with high strength, excellent workability, and excellent LME resistance is provided. A hot-rolled steel sheet of the present embodiment consists of, in mass%, C: 0.040 to 0.120%, Si: 0.01 to 0.60%, Mn: 0.50 to 1.50%, P: 0.025% or less, S: 0.010% or less, Al: 0.010 to 0.070%, N: 0.0070% or less, Ti: 0.055 to 0.200%, and B: 0.0010 to 0.0050%, with the balance being Fe and impurities. In the microstructure of the hot-rolled steel sheet, an area fraction of bainitic ferrite is 85% or more and the dislocation density is 8.0×1013 to 100.0×1013/m2. The average equivalent circular diameter of Ti carbides in the hot-rolled steel sheet is 10 nm or less, and the average equivalent circular diameter of grains of the bainitic ferrite is 15 µm or less.