Microstructural study in AA7075 alloys welded with different filler metals
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MRS Advances © 2019 Materials Research Society DOI: 10.1557/adv.2019.371
Microstructural study in AA7075 alloys welded with different filler metals Juan Manuel Salgado L. 1*, Abraham Silva Hernandez2, Francisco Ignacio López Monroy3, José Luis Ojeda Elizarráras 4 and Jesús Mauricio Tello Rico 5 1
Centro de Ingeniería y Desarrollo Industrial; [email protected]
2
Centro de Ingeniería y Desarrollo Industrial; [email protected]
3
Centro de Ingeniería y Desarrollo Industrial; [email protected]
4
Centro de Ingeniería y Desarrollo Industrial; [email protected]
5
Centro de Ingeniería y Desarrollo Industrial; [email protected]
ABSTRACT Even though AA 7075 is an aluminum alloy with high mechanical properties, it is not often applied in manufacturing. This is so, because it is considered as very difficult to produce defect free welded joints. This is so, because this alloy has a tendency to hot cracking. The metallurgical problems that appear during welding of AA 7075 have not been fully solved but they have been reduced by applying alloys such as: 4043 and 5356 as filler metals. However, in literature there is little information about the metallurgical effects of these types of filler metals applied in arc welded joints of AA7075. This is especially true for Tungsten Inert gas welding. Therefore, this work is focused in comparing the microstructure and Vickers microhardness in weldments of AA 7075 with ER4043, ER5356 and AA7075 as filler metals. Besides, a set of welded joints with the three different filler metals were quenched after welding in order to modify the final microstructure. The results were evaluated by microstructural analysis focused on the Heat Affected Zone and Vickers microhardness and they were compared among them. Centro de Ingeniería y Desarrollo Industrial; [email protected]
1. INTRODUCTION Aluminum alloys are a very important family of alloys for the aeronautical industry due to its lightness and mechanical properties. AA7075 is an aluminum alloy, which has high mechanical properties because it is age hardened. In fact, the tensile strength of this alloy is similar to plain carbon steels. As most of the age hardenable aluminum alloys, AA 7075 is prone to hot cracking and it shows hot tearing in the heat Affected Zone (HAZ), which is seen as microfissuring in the microstructure of the partially melted zone (PMZ) [1]. These facts made AA7075 to be considered as non-
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weldable by arc processes. Examples of these types of problems are shown in figures 1 and 2. AA 7075 is an alloy made of aluminum, zinc, magnesium, copper and other elements in low concentration. Among these alloying elements, zinc shows the higher concentration, followed by magnesium. Literature reports that the microstructure of this alloy sh
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