Análise da microestrutura e da dureza de ligas modificadas a partir da liga A.380 após tratamentos térmicos de solubilização e envelhecimento

Abstract

The purpose of this work is to study the mechanical behavior and the microstructure of three aluminum alloys, where one is pure and the others are coming from the A.380 alloy, each one of them produced with different levels of strontium, 200ppm and 600ppm. The three alloys were casting in metallic molds, making it possible the manufacture of test specimens for the next steps of the work. Was realized six different combinations of heat treatment, using different temperature of solubilization and aging heat, in a sample of each alloy, and then they went prepared for the testing, aiming the mechanical properties characterization of each condition obtained. To evaluate the hardness achieved by each one of the pieces, was adopted the Rockwell B hardness test. To the determination and observation microstructural, was performed the metallographic characterization of all the samples studied. The addition of the strontium proved to be more effective with values close of 200 ppm. The best combination of heat treatment that was found was with the solubilization of 530ºC and aging heat of 155ºC, for the alloy with 200 ppm of strontium. In this case, the greatest microstructural differentiation was perceived, with the presence of a very visible spheroidization of the stages of the eutectic silicon, and a considerable increase in the values of hardness, increasing from 35.4 to 57.5 HRB.