| 摘要 |
A process for obtaining a plate of zirconium alloy comprising at least one portion of excess thickness of at least 0.5 mm relative to a large adjacent face, the portion having edges with angles equal to 90 DEG to 105 DEG and flanks which are connected without depressions to the large adjacent faces. According to the process, a surface portion of a blank plate located straight above a desired portion of excess thickness is coated with a continuous coating which is resistant to a pickling composition to be used, the coated portion widened beyond the desired portion of excess thickness by 0.5-1.5 times the amount of the excess thickness. The coated blank plate is immersed a plurality of times, without passage of electric current, in a pickling bath comprising HF, an oxidizing agent and water, and having a dissolved Zr content less than 12 g/l and a temperature below 35 DEG C. Each immersion removes less than 0.3 mm of thickness over the portions of the blank plate which are not coated. Subsequently, the coating is removed and the blank plate is immersed in the pickling bath for a final treatment. This process can be employed for the preparation of plates of great length which are to be folded, each portion of excess thickness being placed inside a folded angle, in particular to form boxes for ducts for the circulation of fluids. |
