Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-05-22T12:17:06Z
No. of bitstreams: 1
469254 - Texto Completo.pdf: 3137412 bytes, checksum: e261817a0c99d0108e10ccd039c62c92 (MD5) / Made available in DSpace on 2015-05-22T12:17:06Z (GMT). No. of bitstreams: 1
469254 - Texto Completo.pdf: 3137412 bytes, checksum: e261817a0c99d0108e10ccd039c62c92 (MD5)
Previous issue date: 2015-03-23 / The objective of this work is to analyze the influence of annealing and austempering
heat treatments on the machinability with constant pressure of an austempered
ductile cast iron. The results were correlated to microstructural formation and
mechanical properties. It was used the turning process varying the depth of cut, the
speed of cut, the angle of tool and the use of cut fluid. The samples (18 initially
annealed) were heated at 910?C for 90 minutes for austenitization and cooled in salt
bath in one-step at temperatures 300?C, 360?C and 420?C for 30, 60 and 90 minutes.
Other 16 samples (8 previously annealed) were austempered in two-step process at
245oC and 300oC for 5 and 30 minutes, respectively. The samples were analyzed
initially by optical microscopy and mechanical tests (Brinell hardness and Vickers
microhardness), and after were machined in an universal lathe for machinability
tests. The mechanical lathe was instrumented in relation to active power and cutting
time, and the machinability evaluation was made with reference to cutting force,
cutting pressure and material removal index criteria. The samples austempered at
300oC for 30 minutes (with annealing) showed the best machinability, impact
resistance and lowest hardness in the one-step process. However, the samples in
the same temperature and time (with annealing) showed the worst machinability,
highest hardness and lowest impact resistance. The two-step austempering was
performed in 8 samples that showed the best machinability and 8 samples that
showed the worst machinability in one-step process. In these samples, the
machinability test were performed with and without fluid cut and cut angle of 90o and
60o. The results showed the highest performance for the condition austempered at
300oC for 30 minute in two-step process, with previous annealing, when machined
with fluid cut and angle of tool of 60o. The microstructure was composed by
ausferrite, graphite and retained austenite. / Neste trabalho foi investigado atrav?s da t?cnica de aplica??o de press?o
constante, a usinabilidade do ferro fundido nodular austemperado em fun??o de
tratamentos t?rmicos de recozimento e aust?mpera. Os resultados foram
correlacionados com a forma??o microestrutural e com as propriedades mec?nicas.
Para tanto foi utilizado o processo de torneamento, variando a profundidade de
corte, a velocidade de corte, o ?ngulo de posi??o da ferramenta de corte e utiliza??o
e n?o utiliza??o de fluido de corte. Para este fim, 36 amostras (18 recozidas
previamente) foram austemperadas em etapa ?nica nas temperaturas de 300 ?C,
360 ?C e 420 ?C nos tempos de 30 min, 60 min e 90 min. e 16 pe?as (8 com
recozimento pr?vio) em duas etapas ? 245 ?C e 300 ?C nos respectivos tempos de 5
min e 30 min.. Para aust?mpera em etapa ?nica, amostras austemperadas ? 300 ?C
por 30 minutos (sem recozimento pr?vio) obtiveram melhor usinabilidade, resist?ncia
ao impacto e menor dureza. J?, as austemperadas no mesmo tempo e temperatura
(com recozimento pr?vio) obtiveram pior usinabilidade, maior dureza e menor
resist?ncia ao impacto. A aust?mpera em duas etapas foi realizada em 8 pe?as que
obtiveram melhor usinabilidade e em 8 pe?as de pior usinabilidade nos testes de
aust?mpera em ?nica etapa. Estes testes de usinabilidade foram executados com e
sem o uso de fluido de corte utilizando-se os ?ngulos de posi??o da ferramenta de
corte de 90? e 60?. Os resultados apontam para melhor usinabilidade ?s amostras
austemperadas pelo processo de duas etapas e que foram previamente recozidas e
austemperadas ? 300 ?C durante 30 minutos, quando usinadas com fluido de corte e
?ngulo de posi??o da ferramenta de corte de 60?. A microestrutura foi composta por
matriz ausferr?tica, grafita e austenita n?o transformada.
| Identifer | oai:union.ndltd.org:IBICT/oai:tede2.pucrs.br:tede/6049 |
| Date | 23 March 2015 |
| Creators | Werlang Filho, Armindo |
| Contributors | Santos, Carlos Alexandre dos |
| Publisher | Pontif?cia Universidade Cat?lica do Rio Grande do Sul, Programa de P?s-Gradua??o em Engenharia e Tecnologia de Materiais, PUCRS, Brasil, Faculdade de Engenharia |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da PUC_RS, instname:Pontifícia Universidade Católica do Rio Grande do Sul, instacron:PUC_RS |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | -7432719344215120122, 600, 600, 600, -655770572761439785, 4518971056484826825 |
Page generated in 0.0023 seconds