The high strength aluminum alloy extrusion tube and the production method and the tube expander material null Zn which are superior in

摘要

PROBLEM TO BE SOLVED: To provide an extruded pipe of an Al-Zn-Mg-based high-strength aluminum alloy which has excellent tube expansion workability even after having been natural-aged for a long period of time, and is suitable for an outer tube material of a front fork in a motorcycle.;SOLUTION: The extruded pipe made from the aluminum alloy comprises: 3.0-10.0% Zn, 0.5-3.0% Mg, 3.0% or less Cu, further one or more elements of 0.30% or less Cr, 0.60% or less Mn and 0.30% or less Zr, Fe and Si of impurities limited to 0.25% or less respectively, and the balance aluminum with unavoidable impurities of 0.05% or less. The manufacturing method comprises heat-treating the above extruded pipe in a T4 tempered condition so that the heat-treated material can satisfy the relationship of R0-R1≥1.0 nΩm, when R0 is defined as volume resistivity in a T4 tempered condition before being heat-treated and R1 is defined as volume resistivity after having been heat-treated.;COPYRIGHT: (C)2007,JPO&INPIT