Banca de DEFESA: Clayton Rovigatti Leiva

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : Clayton Rovigatti Leiva
DATE: 20/12/2022
TIME: 08:00
LOCAL: Ambiente virtual TEAMS
TITLE:

Influência dos Tratamentos Térmicos de Solubilização e Envelhecimento Artificial na Resistência ao Desgaste Microabrasivo de Ligas de Alumínio 6201

KEY WORDS:

aluminum alloy, AA6201, heat treatment, wear, microhardness.

PAGES: 119
BIG AREA: Engenharias
AREA: Engenharia Mecânica
SUMMARY:

From a rebar composed of AA6201 aluminum alloy, used as an input in the manufacture of wires for the production of CAL900 conductor cables, samples were taken to carry out the present tests, aiming to evaluate the resistance to microabrasive wear after the heat treatments of solubilization and artificial aging. Based on data available in the literature, confirmed and adjusted through the present experimental tests, the hardness of the samples submitted to the solubilization parameters of 550oC with a residence time of 2, 4 and 6 hours and 535oC with a residence time of 1 and 2 hours. In all cases, the Vickers microhardness was measured at around 34 HV(0.5) immediately after quenching. Thus, the solubilization temperature was set at 535oC for a time of 1 hour for submission to subsequent steps. In the artificial aging treatment, after solubilization and quenching, the samples were submitted to a temperature of 170oC for 24, 30, 36, 48 and 60 hours, seeking the hardest condition. In this case, the sample that presented the highest hardness value was the one with a residence time of 30 hours, around 80 HV(0.5). The resistances to microabrasive wear of solubilized samples were then compared with samples that were solubilized and artificially aged for 30 hours. The tests were carried out using a free sphere tribometer, with a CR 52100 (ISO3290) steel sphere, with a nominal diameter of 1 inch. Two series of tests were carried out, both comparing solubilized samples with samples solubilized and artificially aged for 30 hours, but with changes in the parameters of normal force, ball velocity, abrasive particle size, flow and concentration of abrasive slurry and sliding distances. The wear caps were measured and the wear coefficients calculated using Archar's formula. In the first series of tests, the aged sample had an average wear coefficient 21% lower. In the second series of tests, the aged sample had an average wear coefficient 36% lower. The morphology of the caps was evaluated under digital optical microscopy and scanning electron microscopy. Abrasive wear by micro-rolling prevailed in the samples. Regions affected by scratching were also identified. For the first series of tests, regions of adhesive wear were evident, with an irregularly shaped pit morphology, bed with a granular appearance and accentuated deformation of the sample material in the direction of sliding of the sphere. The chemical composition inside the pits was evaluated using EDS and proved to be rich in iron (about 60% by mass), attributing the filling of the grooves to wear debris. As an additional and accessory result, the effects of natural aging on the microhardness of the solubilized samples were evaluated during the 14 days following the solubilization. Bearing in mind the unstable condition of the supersaturated solid solution, in the initial 24 hours, in all samples, a hardening of about 35% due to natural aging was evidenced, and after this period, in the established time window, the microhardness remained relatively constant. The effects of natural aging on the microhardness of the artificially aged samples were evaluated for 3 months, with no significant changes in this period.

BANKING MEMBERS:
Presidente - 1523261 - COSME ROBERTO MOREIRA DA SILVA
Interno - 1249764 - JORGE LUIZ DE ALMEIDA FERREIRA
Externo ao Programa - 2934459 - RODRIGO ARBEY MUNOZ MENESES
Externo à Instituição - VINICIUS ANDRE RODRIGUES HENRIQUES - IME