Effect of Mn and Fe contents on the microstructural evolution of two twin roll caster Al-Fe-Mn-Si alloys

Com o crescimento constante da utilização do processo twin roll caster para a obtenção de chapas de alumínio, torna-se cada vez mais necessário um melhor conhecimento das características das chapas obtidas por este processo. Foram estudadas, nesse trabalho, duas ligas não tratáveis termicamente, 3003 (1,2%Mn; 0,6%Fe) e 8106 (0,4%Mn; 1,5%Fe). As amostras foram retiradas de chapas com 7 mm de espessura a partir de bobinas brutas de fundição e após tratamento térmico de homogeneização de 500°C por 12 horas. As técnicas utilizadas para a caracterização das amostras foram: microscopia óptica com auxílio de luz polarizada, ensaio de microdureza, além dos ensaios de condutividade elétrica.The continuous growth in the usage of the twin roll caster process for aluminum plate production demands a better understanding of the plate's final characteristics. In this work two non-heat treatable largely-used aluminum alloys, namely 3003 (1.2%Mn; 0.6%Fe) and 8106 (0.4%Mn; 1.5% Fe), have been studied. Samples were obtained from 7mm thick plates stemming from rolls in the as-cast condition and after 500°C/12h homogenizing heat treatment. The techniques employed in the sample characterization included: polarized light optical microscopy, microhardness and electrical conductivity tests

Rolling and recrystallization behavior of pure zirconium and zircaloy-4

Rolling and recrystallization of pure zirconium and zircaloy-4 have been studied comparatively in this paper.For the as-received condition, zirconium presented a recrystallized microstructure and the alloy a typical basketweavemicrostructure. Comparative rolling tests were performed, and reduction limit curves as a functionof the rolling temperature were determined. At room temperature, pure Zr shows substantial plasticity and thealloy presents low ductility and many cracks. The ductility of both materials increases significantly with anincrease in rolling temperature at the range between 300 and 500ºC. In static recrystallization studies, samplesof the two materials with similar recrystallized grain size were cold-rolled with a thickness reduction of55%. During annealing, pure Zr and the alloy soften by recovery and recrystallization, however the relativecontribution of recovery is lesser pronounced in the alloy, for which the recrystallization temperature increasesby about 60°C.Keywords: Zirconium, zircaloy-4, rolling, recovery, recrystallization

Crystallographic texture evolution of ferritic stainless steel strips (AISI 430) during cold rolling, annealing and drawing

A evolução da textura, nos estados "como recebido", laminado a frio, recozido e após a estampagem, e a estampabilidade de aços inoxidáveis ferríticos AISI 430, estabilizados ao nióbio, foram estudadas. Duas corridas de chapas com espessuras de 3,0 e 0,7 mm foram utilizadas. A de maior espessura foi relaminada a frio e recozida. A de menor espessura, de composição química semelhante à primeira, foi laminada a frio, na usina siderúrgica, e, posteriormente, submetida a estampagem. A textura foi avaliada usando DRX em todas as condições. O aço AISI 430, na condição "como recebido", apresentou forte textura {100}<110>, {100}<120> e a fibra g. Após a deformação, a intensidade da fibra g aumentou e apareceu a fibra a. O recozimento causou o desaparecimento da fibra a e o fortalecimento da fibra g, que é uma textura adequada para a estampagem. Embora o aço AISI 430, de espessura 0,7 mm, tivesse apresentado uma forte textura de fibra g, no estado inicial, as propriedades de estampagem não foram boas e o material trincou durante a conformação.Texture evolution in AISI 430 Nb stabilized ferritic stainless steels in the "as-received", hot-and cold-rolled, annealed and stamped conditions have been studied, along with their formability. Two ferritic stainless steels (Nb stabilized) having a thickness of 3.0 and 0.7mm, were employed. The thicker one was cold rolled and annealed. The thinner one, with similar composition, was cold rolled at the steel plant and subsequently submitted to deep drawing. Texture has been evaluated using DRX for all conditions. The AISI 430 stainless steel, in the "as-received" condition presented a strong {100} texture in the <110> and <120> directions and the gamma fibre. After cold rolling the material presented stronger gamma and weaker alpha fibres. Annealing of the cold rolled steel conduced to the vanishing of the alpha fibre and strengthening of the gamma fibre, adequate for deep drawing operations. Although the AISI 430 stainless steel of 0.7mm presented a strong gamma fibre, other deep drawing properties were inadequate and the material cracked on stamping.FAPES

Predicting Delta Ferrite Content in Stainless Steel Castings

The distribution of delta ferrite fraction was measured with the magnetic method in specimens of different stainless steel compositions cast by the investment casting (lost wax) process. Ferrite fraction measurements published in the literature for stainless steel cast samples were added to the present work data, enabling an extensive analysis about practical methods to calculate delta ferrite fractions in stainless steel castings. Nineteen different versions of practical methods were formed using Schaeffler, DeLong, and Siewert diagrams and the nickel and chromium equivalent indexes suggested by several authors. These methods were evaluated by a detailed statistical analysis, showing that the Siewert diagram, including its equivalent indexes and iso-ferrite lines, gives the lowest relative errors between calculated and measured delta ferrite fractions. Although originally created for stainless steel welds, this diagram gives relative errors lower than those for the current ASTM standard method (800/A 800M-01), developed to predict ferrite fractions in stainless steel castings. Practical methods originated from a combination of different chromium/nickel equivalent indexes and the iso-ferrite lines from Schaeffler diagram give the lowest relative errors when compared with combinations using other iso-ferrite line diagrams. For the samples cast in the present work, an increase in cooling rate from 0.78 to 2.7 K/s caused a decrease in the delta ferrite fraction, but a statistical hypothesis test revealed that this effect is significant in only 50% of the samples that have ferrite in their microstructures.FAPESP (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo) [95/9113-2, 96/04242-1, 03/08576-7]Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP

Texture analysis of cold rolled and annealed aluminum alloy produced by twin-roll casting

A 7.4 mm thick strip of 3003 aluminum alloy produced by the industrial twin-roll casting (TRC) process was homogenized at 500 °C for 12 hours, after which it was cold rolled in two conditions: 1) to reduce the strip's thickness by 67%, and 2) to reduce it by 91%. The alloy was annealed at 400 °C for 1 hour in both conditions. The results revealed that a rotated cube texture, the {001}<110&gt; component, predominated in the as-cast condition and was transformed into brass, copper and S type textures during the cold rolling process. There was practically no difference between the deformation textures at the two thickness reductions

A comparative study in AA4006 alloy strips produced by twin roll caster and direct chill processes: microstructure and crystallographic texture

Nesse trabalho, foi realizado um estudo comparativo da microestrutura e da textura cristalográfica entre chapas da liga AA4006 produzidas por dois processos industriais de lingotamento: contínuo (Twin roll caster TRC) e semicontínuo (Direct chill DC). Para a caracterização microestrutural, foram utilizadas as técnicas de microscopia óptica com luz polarizada, microscopia eletrônica de varredura, medidas de condutividade elétrica e ensaios de dureza Brinell. A textura cristalográfica foi determinada por difração de raios X. Foram detectadas e discutidas diferenças significativas nas morfologias e distribuições de grãos e de partículas de fases intermetálicas. O estudo da textura cristalográfica foi realizado ao longo da espessura das tiras e os resultados mostraram variações significativas da textura entre as chapas ao longo da espessura. A chapa produzida por lingotamento contínuo apresentou uma típica textura de cisalhamento, nas proximidades de sua superfície, enquanto que, nas regiões mais internas, a fibra &#946; foi observada

ATLANTIC EPIPHYTES: a data set of vascular and non-vascular epiphyte plants and lichens from the Atlantic Forest

Epiphytes are hyper-diverse and one of the frequently undervalued life forms in plant surveys and biodiversity inventories. Epiphytes of the Atlantic Forest, one of the most endangered ecosystems in the world, have high endemism and radiated recently in the Pliocene. We aimed to (1) compile an extensive Atlantic Forest data set on vascular, non-vascular plants (including hemiepiphytes), and lichen epiphyte species occurrence and abundance; (2) describe the epiphyte distribution in the Atlantic Forest, in order to indicate future sampling efforts. Our work presents the first epiphyte data set with information on abundance and occurrence of epiphyte phorophyte species. All data compiled here come from three main sources provided by the authors: published sources (comprising peer-reviewed articles, books, and theses), unpublished data, and herbarium data. We compiled a data set composed of 2,095 species, from 89,270 holo/hemiepiphyte records, in the Atlantic Forest of Brazil, Argentina, Paraguay, and Uruguay, recorded from 1824 to early 2018. Most of the records were from qualitative data (occurrence only, 88%), well distributed throughout the Atlantic Forest. For quantitative records, the most common sampling method was individual trees (71%), followed by plot sampling (19%), and transect sampling (10%). Angiosperms (81%) were the most frequently registered group, and Bromeliaceae and Orchidaceae were the families with the greatest number of records (27,272 and 21,945, respectively). Ferns and Lycophytes presented fewer records than Angiosperms, and Polypodiaceae were the most recorded family, and more concentrated in the Southern and Southeastern regions. Data on non-vascular plants and lichens were scarce, with a few disjunct records concentrated in the Northeastern region of the Atlantic Forest. For all non-vascular plant records, Lejeuneaceae, a family of liverworts, was the most recorded family. We hope that our effort to organize scattered epiphyte data help advance the knowledge of epiphyte ecology, as well as our understanding of macroecological and biogeographical patterns in the Atlantic Forest. No copyright restrictions are associated with the data set. Please cite this Ecology Data Paper if the data are used in publication and teaching events. © 2019 The Authors. Ecology © 2019 The Ecological Society of Americ