RAPID EXTRUSION OF HOT-SHORT-SENSITIVE ALLOYS

摘要

High-strength aluminum alloys and other hot-short-sensitive alloys can be extruded at rapid rates through a cooled, double reduction die (3) without hot-short cracking or scoring caused by die pickup. A primary reduction die (4) has a long, cooled primary land (5) and is followed by a secondary reduction die (6). A metal billet (15) may be extruded through the primary die (4) at about the solidus temperature of its lowest melting phase, then cooled as it passes through the primary die land (5) to reduce or maintain the temperature below the solidus temperature and, finally, the primary extrusion is reduced in cross section in the secondary die (6) by about 2-50%. The temperature, the back pressure caused by the second reduction, and the low friction through the primary land (5) contribute to eliminate hot-short cracks and minimize serious pickup scoring at surprising rates of at least about 18 meters per minute (60 ft/min) for 2024 aluminum rod.