| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of subjecting steel having a thickness of≥170 mm and high crack sensitivity to gas cutting without generating delayed cracks. SOLUTION: In the gas cutting method for steel 1 comprising, by mass, C+Mn/6≥0.3% or Nb+V≥0.02%, and having a thickness of≥170 mm, the vicinity of a normal cutting line 6 is subjected to previous gas cutting before normal cutting, and the surface temperature of the steel in the normal cutting line 6 directly before the normal cutting is≥250°C. Alternatively, the interval T between the normal cutting line 6 and the previous gas cutting line 5 is≤30 mm, and the distance L between a previous cutting torch 3 and a normal cutting torch 4 in a feeding direction is≤300 mm. One cutting machine 2 is loaded with both the previous cutting torch 3 and normal cutting torch 4. COPYRIGHT: (C)2005,JPO&NCIPI
|
