| 摘要 |
PURPOSE:To manufacture an electric resistance welded steel pipe excellent in HIC resistance and SSCC resistance properties. CONSTITUTION:(a) A process preparing a hot rolled plate containing 0.001 to 0.1% Nb and 0.001 to 0.006% Ca in a carbon steel, (b) a process forming this hot rolled plate continuously to an open pipe by multistage forming rolls, (c) a process heating both edge parts of the open pipe, which oppose each other, by an electric resistance, and (d) a process further irradiating the both edge parts heated by the electric resistance with a laser beam, controlling the quantity of upset by a squeeze roll, and being in press welding, are provided. |
