To prevent cracking caused by the local melting in an inner circumferential surface of a hollow extruded material when manufacturing the hollow extruded material of an aluminum alloy in a mandrel system in a hot extrusion method.
When manufacturing a hollow extruded material of an aluminum alloy by a mandrel system, the temperature of an outer circumferential surface 10 of a mandrel 1 during the extrusion of a billet is maintained at the temperature equal to or lower than T-50(C), where T(C) is the melting point of the billet. Since the temperature of the billet in contact with the outer circumferential surface of the mandrel during the extrusion of the billet is equal to or not higher than the melting point T(C) of the billet, cracking caused by the local melting can be prevented on the inner circumferential surface of the hollow extruded material.
NAKAI YASUHIRO
KATO KATSUYA
| JPS5731408A | 1982-02-19 |
Yoshiyuki Fujiki