| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a high-carbon electro-resistance-welded steel pipe having an electro-resistance-welded portion excellent in reliability.SOLUTION: A method for manufacturing a high-carbon electro-resistance-welded steel pipe, in which a base material steel plate is molded into a nearly cylindrical form by cold working and the molding is subjected to electro-resistance-welding to form the electro-resistance-welded steel pipe, includes: using a high-carbon steel plate containing C of 0.30-0.60 mass%, Si of 0.05-0.50 mass%, Mn of 0.30-2.0 mass%, Al of 0.50 mass% or less, N of 0.0100 mass% or less and composed of the balance Fe and inevitable impurities for a base material steel plate; and after the electro-resistance-welding, applying cold drawing rolling of a drawing rate of 0.8% or less to the resultant molding, and then immediately reheating or cooling and reheating the resultant molding, and then applying hot diameter contraction rolling to the resultant molding at a diameter contraction rate of 10% or more in a temperature range of 850°C or more. This method suppresses the defect occurrence of an electro-resistance-welded portion to provide the electro-resistance-welded portion excellent in reliability, thereby obtaining a high-carbon electro-resistance-welded steel pipe markedly improved in reliability. Further, the use of these high-carbon electro-resistance-welded steel pipes as a base material allows reliability of automobile components to be improved.</p> |
