| 摘要 |
PURPOSE:To prevent the danger of breakage in passing through a line by joining the end edge of a preceding material of special steel and the end edge of a succeeding material by welding, and forcibly and quickly cooling the weld zone right after the welding down to specific temps., then subjecting the same to a heat treatment. CONSTITUTION:The end edge of a preceding material of special steel which is carbon steel or alloy steel having >=0.30% content of carbon and the end edge of a succeeding material are joined by flash butt welding. The weld zone right after the welding is once forcibly cooled by air cooling or water cooling down to temp. lower by >=100 deg.C than the Ms point of the special steel. Thence, it is subjected to the post heat treatment by which the structure of sorbitic tempered martensite is obtd. Thereby, the danger of the breakage of the weld zone is averted without decreasing the line speed during passing through the continuous line. |
