| 摘要 |
1502114 Extruding at specified temperatures SOC DE VENTE DE L'ALUMINIUM PECHINEY 3 April 1975 [4 April 1974] 13649/75 Headings B3P B3V and B3Q A method of shaping an alloy at a higher than normal forming ratio and/or speed and with reduced tool wear comprises heating the alloy to a temperature between the solidus and liquidus points until less than 40% by weight of the alloy has liquefied, maintaining the temperature for between 5 minutes and 4 hours so that the solid dentritic phase has at least begun to change into a globular form, Fig. 2 (not shown), and working the alloy in this condition. Profiles of various section, bar, wire and tubes may be formed by operations such as drawings, extrusion, rolling, stamping, swaging and forging. The heat treatment permanently modifies the alloy structures so that a billet cooled after the heat treatment may have the improved, "rheotropic" working properties restored merely by heating to the solidus-liquidus range. In an example aluminium alloy billets were heated to 585-605‹ C. for 15 minutes to give a liquid content of 6-13%. The billets were extruded from a container heated to 420- 450‹ C., through a water-cooled die at an exit temperature of 450‹ C. Tests were carried out immediately after extrusion, after ageing for 8 hours at 175‹ C. and following water quenching after 2 hours at 505‹ C. and the above ageing. In numerous other aluminium alloy examples temperatures ranged between 572-625‹ C., times between 15 and 30 minutes and liquid content between 4 and 25%. The work may be cooled with air or water as it issues from a die to solidify substantially all of the liquid fraction. |
