| 摘要 |
In a process for the manufacture of products of beryllium or beryllium alloy, particularly casings for fuel rod in nuclear reactors, cast beryllium or beryllium alloy is subjected in the course of its shaping to a thorough plastic hot working such as extrusion in one or more steps and is stress-relieved at a temperature in the range 550 DEG C. to 750 DEG C., i.e. below and close to the recrystallization temperature, whilst imparting a tensile force to straighten the extruded beryllium or beryllium alloy, and then subjected to controlled recrystallization annealing. There may optionally be a compression before the hot working and a warm drawing after it. The hot working may be an impact extrusion, the metal being coated with a thin layer of silver or an extrusion under a casing of soft steel. A pre-extrusion may be carried out under a thin casing followed by extrusion under a thick casing. In an example where the process is used for the production of beryllium tubes, a cast ingot is compressed for 2 minutes at 650 DEG C. under a pressure of 10,000 bars. Extrusion at 950 DEG C. is carried out under a casing of soft steel 2 mm. thick until the cross-sectional area of the billet is reduced by a factor of 6. The billet is cut into sections and pierced. A second extrusion at 950 DEG C. is carried out at 27 mms. per second, the cross-sectional are of the billets being reduced by a factor of 15. The tubes thus produced are stress relieved at 650 DEG C. for half an hour whilst a tensile force is imparted to them to straighten them and then annealed at 750 DEG C. for 4 hours. |
