Aluminum alloy hollow material, aluminum alloy extruded pipe material for air conditioner piping and process for producing the same
View Patent ↗Disclosed are aluminum alloy hollow materials and processes for producing the same wherein an aluminum alloy hollow material is produced by subjecting an ingot of an aluminum alloy containing 0.3˜1.5 wt % Mn to port hole extrusion or port hole extrusion and drawing-elongation processing and wherein a difference in electric conductivity between individual portions in lengthwise direction of the hollow material is not more than 1.0 IACS %. According to the aluminum alloy hollow materials, preferential corrosion in welding potions in port hole extrusion can be prevented.
1. A method of preventing preferential corrosion of an extruded material, the method comprising:
homogenizing an aluminum alloy ingot, wherein the aluminum alloy ingot consists of 0.8-1.5 wt % Mn, 0.1-0.7 wt % Fe, and 0.03-0.6 wt % Si, and optionally one or more of 0.00-0.45 wt % Cu, 0.0-0.3 wt % Mg, 0.0-0.3 wt % Cr, 0.0-0.1 wt % Ti, 0.0-0.5 wt % Zn, 0.0-0.3 wt % Zr and 0.0-0.3 wt % Ni, the balance being aluminum and any unavoidable impurities;
port hole extruding the aluminum alloy ingot to produce a port hole extruded aluminum alloy; and
drawing the port hole extruded aluminum alloy to form a hollow material, wherein a difference in electric conductivity of individual portions in a lengthwise direction of the hollow material is not more than 1 IACS %, and such that an electric conductivity value becomes at least 39.0 IACS %;
wherein said homogenizing is regulated to precipitate sufficient Mn prior to extruding and drawing so as to produce said 1 IACS % or less conductivity difference in a lengthwise direction of the hollow material and wherein said homogenizing of the ingot is carried out by maintaining the ingot at a first temperature of 500-630° C. for more than zero but not more than about 24 hours, cooling the ingot down to a second temperature of 400-500° C. at a cooling velocity of not more than 100° C./hr, and maintaining the ingot at said second temperature for about 4 to 48 hours and
wherein a preferential corrosion of a welded portion of the hollow material is inhibited.
2. A method of preventing preferential corrosion of an extruded material, the method comprising:
homogenizing an aluminum alloy ingot, wherein the aluminum alloy ingot consists of 0.8-1.5 wt % Mn, 0.1-0.7 wt % Fe, and 0.03-0.6 wt % Si, and optionally one or more of 0.00-0.45 wt % Cu, 0.0-0.3 wt % Mg, 0.0-0.3 wt % Cr, 0.0-0.1 wt % Ti, 0.0-0.5 wt % Zn, 0.0-0.3 wt % Zr and 0.0-0.3 wt % Ni, the balance being aluminum and any unavoidable impurities;
port hole extruding the aluminum alloy ingot to produce a port hole extruded aluminum alloy; and
drawing the port hole extruded aluminum alloy to form a hollow material, wherein a difference in electric conductivity of individual portions in a lengthwise direction of the hollow material is not more than 1 IACS %, and such that an electric conductivity value becomes at least 39.0 IACS %;
wherein said homogenizing is regulated to precipitate sufficient Mn prior to extruding and drawing so as to produce said 1 IACS % or less conductivity difference in a lengthwise direction of the hollow material and wherein said homogenizing of the ingot is carried out by raising the ingot to a temperature (T1) of 500-630° C., maintaining said ingot at said temperature T1 for more than zero but not more than about 16 hours, cooling the ingot from the temperature T1 to 350° C. (T2) at a cooling velocity of not more than 100° C./hr, wherein the time between reaching the temperature T1 to reaching the temperature T2 is maintained within 10-48 hrs, and cooling the ingot at an optional cooling velocity from the temperature T2 to room temperature and,
wherein a preferential corrosion of a welded portion of the hollow material is inhibited.
3. A method of preventing preferential corrosion of an extruded material, the method comprising:
homogenizing an aluminum alloy ingot, wherein the aluminum alloy ingot consists of 0.8-1.5 wt % Mn, 0.1-0.7 wt % Fe, and 0.03-0.6 wt % Si, and optionally one or more of 0.00-0.45 wt % Cu, 0.0-0.3 wt % Mg, 0.0-0.3 wt % Cr, 0.0-0.1 wt % Ti, 0.0-0.5 wt % Zn, 0.0-0.3 wt % Zr and 0.0-0.3 wt % Ni, the balance being aluminum and any unavoidable impurities;
port hole extruding the aluminum alloy ingot to produce a port hole extruded aluminum alloy; and
drawing the port hole extruded aluminum alloy to form a hollow material, wherein a difference in electric conductivity of individual portions in a lengthwise direction of the hollow material is not more than 1 IACS %, and such that an electric conductivity value becomes at least 39.0 IACS %;
wherein said homogenizing is regulated to precipitate sufficient Mn prior to extruding and drawing so as to produce said 1 IACS % or less conductivity difference in a lengthwise direction of the hollow material and wherein said homogenizing of the ingot is carried out by maintaining the ingot at a temperature of 400-500° C. for 0.5-4 hours, elevating the temperature up to 550-630° C., maintaining the temperature for 0.5-4 hrs., cooling the ingot to 350° C. at a cooling velocity of not more than 100° C./hr, and cooling the ingot from 350° C. to room temperature at an optional cooling rate and,
wherein a preferential corrosion of a welded portion of the hollow material is inhibited.
4. The method of claim 3 , comprising drawing the material to manufacture pipe material that is substantially free of surface striations.
5. The method of claim 1 , comprising drawing the material to manufacture pipe material that is substantially free of surface striations.
6. The method of claim 2 , comprising drawing the material to manufacture pipe material that is substantially free of surface striations.