[en] FATIGUE LIFE OF A FERRITIC NODULAR CAST IRON OF DIFFERENT MICROSTRUCTURES.
[pt] VIDA EM FADIGA DE UM FERRO FUNDIDO NODULAR FERRÍTICO COM VARIAÇÕES MICROESTRUTURAIS
| dc.contributor | MARCOS VENICIUS SOARES PEREIRA | |
| dc.creator | CARLOS ALBERTO TORRES DE MELLO | |
| dc.date | 2003-07-16 | |
| dc.date.accessioned | 2022-09-21T21:41:50Z | |
| dc.date.available | 2022-09-21T21:41:50Z | |
| dc.identifier | https://www.maxwell.vrac.puc-rio.br/colecao.php?strSecao=resultado&nrSeq=3721@1 | |
| dc.identifier | https://www.maxwell.vrac.puc-rio.br/colecao.php?strSecao=resultado&nrSeq=3721@2 | |
| dc.identifier | http://doi.org/10.17771/PUCRio.acad.3721 | |
| dc.identifier.uri | https://hdl.handle.net/20.500.12032/42127 | |
| dc.description | [pt] Esta pesquisa teve como objetivos promover variações microestruturais em um ferro fundido nodular ferrítico tipo ASTM A536 60-40-18, pelo do uso de resfriadores durante a solidificação do material e pela adoção de tratamentos térmicos pós-fundição, bem como avaliar a influência de tais variações microestruturais sobre as propriedades mecânicas e vida em fadiga do material. Inicialmente, amostras do material foram fundidas em areia com e sem o uso de resfriadores. Após a fundição, algumas amostras de ambas as condições de resfriamento sofreram normalização, enquanto outras foram recozidas, perfazendo seis diferentes condições microestruturais: sem resfriador bruta de fundição (SRB); sem resfriador normalizada (SRN); sem resfriador recozida (SRR); com resfriador bruta de fundição (CRB); com resfriador normalizada (CRN) e com resfriador recozida (CRR). Em seqüência, corpos de prova de todas as condições mencionadas acima foram ensaiados em tração e, posteriormente, sofreram análises metalográficas qualitativas e quantitativas. Dando continuação a etapa experimental, levantaramse as curvas tensão versus número de ciclos para a falha das condições microestruturais SRB, SRR, CRB e CRR, por meio de ensaios de fadiga em flexão rotativa. A vida em fadiga do material também foi relacionada com às características metalúrgicas de cada condição. | |
| dc.description | [en] The objectives of the present work were to promote microstructural variations in an ASTM A 536 60-40-18 ferritic nodular cast iron, making use of cast coolers during and adopting heat treatments after casting, as well as to evaluate the influence of the microstructural variations on the mechanical properties and fatigue life of the material. Initially, samples of the material were cast in sand moulds with and without internal coolers. After casting, a number of samples in both cooling conditions were subjected to normalizing and annealing heat treatments and, therefore, six different microstructural conditions were obtained: as- cast without cooler (SRB), normalized without cooler (SRN), annealed without cooler (SRR), as-cast with cooler (CRB), normalized with cooler (CRN) and annealed with cooler (CRR). Tensile test were carried out on specimens representing the above mentioned conditions and their microstructures were analysed by qualitative and quantitative metallography. In the sequence of the experimental procedure, rotating bend fadigue test were performed in order to establish the stress-life curves for the SRB, SRR, CRB and CRR microstructural conditions. The fadigue life of the material was also related to the metallurgical characteristics of each condition. The metallographic analysis has indicated that the use of coolers increases the number of graphite nodules, reduces the graphite nodule size and otimizes the spherical morphology. However, these microstructural modifications seam to have no significant influence on the mechanical properties of the material. As to the effect of normalizing annealing, boht treatments not imply in significant changes in the mechanical properties of the as-cast conditions. Regarding the fadigue resistance of the material in the as-cast conditions, the CRB sample showed a longer fatigue life than the SRB samples and this performance under cyclic loading was attributed to the fact that the CRB condition is characterized by a higher number of graphite nodules of class VI. A comparison between the as-cast and annealed conditions indicated that the microstructural conditions SRR and CRR presented a lower fatigue resistance than the conditions SRB and CRB, respectively. This behaviour was associated with the microstructural features of the as-cast conditions, namely the smaller graphite nodule size, the higher microhardness of the matrix and the presence of the bull`s-eye structure. Finally, the experimental stress-life curves were modelled by means of Coffin-Manson law, which was considered efficient in the fadigue life data of ferritic nodular cast iron. | |
| dc.language | pt | |
| dc.publisher | MAXWELL | |
| dc.subject | [pt] CURVAS S-N | |
| dc.subject | [pt] METALOGRAFIA QUANTITATIVA | |
| dc.subject | [pt] TRATAMENTOS TERMICOS | |
| dc.subject | [en] S-N CURVES | |
| dc.subject | [en] QUANTITATIVE METALLOGRAPHY | |
| dc.subject | [en] HEAT TREATMENTS | |
| dc.title | [en] FATIGUE LIFE OF A FERRITIC NODULAR CAST IRON OF DIFFERENT MICROSTRUCTURES. | |
| dc.title | [pt] VIDA EM FADIGA DE UM FERRO FUNDIDO NODULAR FERRÍTICO COM VARIAÇÕES MICROESTRUTURAIS | |
| dc.type | TEXTO |
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