Study on Welded strength and die life assessment for follow extruded Aluminum Alloy 7075
| Autor: | Kuo Kun Hong, 郭坤洪 |
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| Rok vydání: | 2011 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 Al7075 has many good mechanical properties; however, its bonding strength is very poor and is difficult to produce extruded hollow products. Although some researchers proposed different method to study welding strength of Aluminum alloy, the study for high strength Aluminum alloy in hollow extrusion process is not enough. This study use DEFORM 3D finite element analysis software to simulate two different types of hollow extruding die configurations for square tube extrusion process, namely: type (1) welding position at the corners of the square tube and type (2) at the edges. The welding strengths of these two kinds of extruded tube are studied by expanding test and tensile test. The service lives of these two extrusion die components are studied based on the die stress and die wear information from DEFORM simulations. Some information about the study are as follows: billet material is Al7075, billet diameter is 127mm, the extruded tube outside dimension is 54mm x 54mm, thickness is 5mm, extrusion temperature is 470℃, and ramp speed is 0.5mm/s, die material is SKD61 with HRC48. Research results show that the maximum extrusion force is 711 tons, material velocity is 4.7 mm/s in welding chamber, and the speed difference between the two split materials is 0.3 mm/s for type (1); the maximum extrusion force is 771 tons, material velocity is 5.4 mm/s and the speed difference between the two split materials is 0.8 mm/s for type (2). Analysis results for extrusion die are as follows: the maximum equivalent die stress, die wear and service life both in top die and lower die are 1120 MPa, 896 MPa, 0.4823 mm, 0.4729 mm, 71 times and 610 times, respectively for type (1); 1020 MPa, 820 Mpa, 0.4532 mm, 0.4595 mm, 162 times and 1400 times for type (2). The average maximum tube expanding forces are 2.88 tons for type (1) and 4.1 tons for type (2), respectively. The welding strength for type (2) square tube is above 200 MPa on each welding interface that is greater than the bonding strength of aluminum alloy 6061, 6063. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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