PORTHOLE EXTRUDED MATERIAL FOR HOT BULGE FORMING AND METHOD FOR MANUFACTURING THE SAME

PROBLEM TO BE SOLVED: To provide a hollow extruded material of an Al-Mg-Si-based aluminum alloy capable of increasing strength in the vicinity of a welded part and increasing an expansion rate, and capable of achieving a workpiece with an even plate thickness distribution by preventing a constriction when the hollow extruded material of the Al-Mg-Si-based aluminum alloy is subjected to hot bulging.SOLUTION: When a square area with a side length of 500 μm including 40 or more crystal grains is selected from an area demarcated by a range of 2 mm on both sides with a welding line as its middle in a direction vertical to the welding line on a surface vertical to a direction of extruding the porthole hollow extruded material of Al-Mg-Si-based aluminum alloy, and t/10 to 9t/10 of plate thickness t of the hollow extruded material from a surface of the hollow extruded material in a direction parallel to the welding line, the minimum value of an area ratio of the crystal grains in a Cube orientation is set to be 10-50%, and the difference of the maximum value and the minimum value of the area ratio of the crystal grains in the Cube orientation is set to be 60% or less.