| 摘要 |
A process for manufacturing a hollow pressure vessel, in which a billet is cast from an alloy with a composition in % by weight, Zn=6.25-8.0, Mg=1.2-2.2, Cu=1.7-2.8, Fe<0.20, Fe+Si<0.40, at least one of the elements selected from the group consisting of Cr, Zr, V, Hf and Sc in an amount of 0.05-0.3, and other elements <0.05 each and <0.15 total. The cast billet is homogenized with a temperature profile such that metal temperature is slightly less than incipient melting temperature at all times, cooled to ambient temperature and softening annealed for a duration of 20 to 40 h between 200 and 400° C. with cooling at a rate of less than 50° C./h down to a temperature of below 100° C., resulting in a billet hardness <54 HB. A slug is cut out of the softened billet, cold or slightly warm extruded with an extrusion start temperature <300° C., to form a casing which is necked, solution heat treated at a temperature slightly below the incipient melting temperature, for a duration sufficient to obtain an absolute value of specific energy associated with a DTA thermogram signal of less than 3 J/g, quenched in cold water, and aged at between 100 and 200° C. for a duration between 5 and 25 h. |
