Efecto del Tiempo y Temperatura del Tratamiento Térmico de Homogenización en la Microestructura y Resistencia a la Corrosion de la Aleacion de Aluminio 6063

Published in: Engineering for a Smarter Planet: Innovation, ITC, and Computational Tools for Sustainable Development: Proceedings of the 9th Latin American and Caribbean Conference for Engineering and Technology
Date of Conference: August 3-5, 2011
Location of Conference: Medellin, Colombia
Authors: Linda Gil
Sugehis Liscano
Maria Rodriguez
Refereed Paper: #299

Abstract

The commercial alloy of aluminium 6063 belongs to the system Aluminium-Magnesium-Silicon, is characterized by its high capacity to the extrusion, for what it must expire with requirements in mechanical properties and of superficial quality, such as low roughness, free of cracks or pits. To assurance a microstructure adapted for the extrusion a homogenized thermal treatment is applied to the alloy. Nevertheless, there has not been sufficiently studied the effect of the thermal treatment in the resistance to the corrosion. In this research was evaluated the effect of temperature and time of maintenance the heat treatment of homogenized on the resistance to the corrosion, and microstructure of the alloy 6063. The assessment of the properties of the alloy took place before and after treatment. The times of homogenized were 1,2 y 3 hours at temperatures of homogenization of 560, 580 y 600 °C. The corrosion resistance was evaluated by electrochemical technique of potentiodinamic cyclic polarization (ASTM G-69). The microstructural characterization of alloy and corrosion products was assessed by optical microscopy techniques with image analysis, scanning electron microscopy with microanalysis by EDS. The results show that increasing the time homogenized influences resistance to corrosion, in the grain size and the volume fraction transformed of β-AlFeSi (Al 5 FeSi) phase to α-AlFeSi (Al 8 Fe 2 Si), obtaining the best properties for a time of 3 hours. The mechanism of corrosive attack occurs by the formation of local chemical cell, caused by differences in the electrochemical activity between precipitated phases and matrix alloy heat-treated.