scholarly journals Influence of the Cooling Rate on the Morphology of Spheroidic Graphite Obtained by the CO2 Process

2013 ◽  
Vol 8 (22) ◽  
pp. 37
Author(s):  
Mauro Carlos Souza ◽  
Antonio Carlos de Araújo Santos ◽  
Wilma Clemente de Lima Pinto ◽  
Mila Rosendal Avelino

The mechanical properties of cast metallic materials are strongly influenced by processing parameters, such as percentage of silicate, sand granulometry, and metallurgical processing. The ductile iron cast produced by the CO2 process depends on variables that determine the behavior of the material in service, such as the cooling rate and chemical composition. This study evaluated the influence of the cooling rate on the spheroidic graphite. In order to determine this effect, a simulation was performed in specimens with 20, 25, and 30 mm in thickness, through the characterization of type, measurement of nodule size, and distribution of nodules. Chemical analysis and mechanical resistance tests were performed. The 25 mm thick specimen showed the best behavior among the three thicknesses evaluated, presenting the formation of many small nodules and a small amount of larger nodules in the center.

2013 ◽  
Vol 8 (22) ◽  
pp. 37-41
Author(s):  
Mauro Carlos Souza ◽  
Antonio Carlos de Araújo Santos ◽  
Wilma Clemente de Lima Pinto ◽  
Mila Rosendal Avelino

The mechanical properties of cast metallic materials are strongly influenced by processing parameters, such as percentage of silicate, sand granulometry, and metallurgical processing. The ductile iron cast produced by the CO2 process depends on variables that determine the behavior of the material in service, such as the cooling rate and chemical composition. This study evaluated the influence of the cooling rate on the spheroidic graphite. In order to determine this effect, a simulation was performed in specimens with 20, 25, and 30 mm in thickness, through the characterization of type, measurement of nodule size, and distribution of nodules. Chemical analysis and mechanical resistance tests were performed. The 25 mm thick specimen showed the best behavior among the three thicknesses evaluated, presenting the formation of many small nodules and a small amount of larger nodules in the center.


This paper presents the investigation of moderate properties of solidified Al (LM6)+SiCp metal matrix composite (AMMC). These AMMC is fabricated by considering five different parts of casting and different weight of SiCp for reinforcement. The SiCp wt. % is varied from 5 wt. % to 15 wt. % with a step size 5 %. During casting, temperature is measured using K-thermocouple and temperature vs. solidification curve is traced. These results are compared with the solidification results of Al (LM6) alloy. It is observed that the solidifying duration of AMMC increased as well as decreased liquid temperature by adding SiCp to it. The trend of the curve is also presented that the cooling rate and the duration of solidification are different for different part of casting. Mechanical property of the each five parts of casting is tabulated. It is observed from the properties that the mechanical properties of AMMC increased by increasing the wt. % of the reinforced particles SiCp.


2012 ◽  
Vol 182-183 ◽  
pp. 162-166
Author(s):  
Can Can Li ◽  
Hao Ran Geng ◽  
Zhen Yuan Li ◽  
Hai Ou Qin

In this paper, Al-12.6%Si/Al63Cu25Fe12 composites were fabricated by method of casting. The microstructure and chemical composition of Al63Cu25Fe12 quasicrystal alloy and Al-12.6%Si alloy reinforced by the quasicrystal were studied, and the mechanical properties of Al-12.6%Si composite were also measured. The results show that almost single quasicrystalline phases exist in the samples which are cast with the 1300°C melt. Quickly enough cooling rate and appropriate melt temperature are necessary for the formation of the quasicrystalline phase. In addition, Al-12.6%Si composite has optimal mechanical properties when the amount of Al63Cu25Fe12 quasicrystal is 3 wt%.


Author(s):  
Natalia Cordeiro Noce ◽  
Tatiane de Campos Chuvas ◽  
Luís Felipe Guimarães de Souza ◽  
Matheus Campolina Mendes

1997 ◽  
Vol 3 (S2) ◽  
pp. 691-692
Author(s):  
K.C. Hsieh ◽  
E.A. Kenik

There has been increasing interest from industry to characterize the different precipitate distributions in ferrous materials to account for different mechanical properties that are observed. For this study, two different heat treatments were chosen for the experimental S5 tool steel, modified to have 0.24 wt% C. Alloy S5-1 received 1 hour of austenitizing at 970°C, was quenched at rate of 140°C/s and tempered for 1 hour at 200°C. Alloy S5-2 received 40 minutes of austenitizing at 940°C, was quenched at rate of 16°C/s and tempered for 1 hour at 200 °C. In this relatively low hardenability steel, both S5-1 and S5-2 show mixed microstructures of tempered martensite and bainite (Fig. 1, 2). Not surprisingly, the slower cooling rate for S5-2 created an alloy with inferior microstructure and mechanical properties. Even though these differences in precipitate distributions, could not directly account for differences in mechanical properties, it is of interest to study how the different heat treatments affected the precipitate distributions in S5-1 and S5-2.


Author(s):  
E Lodins ◽  
I Rozenstrauha ◽  
L Krage ◽  
L Lindina ◽  
M Drille ◽  
...  

2006 ◽  
Vol 509 ◽  
pp. 165-170 ◽  
Author(s):  
Alla Kabatskaia Ivanovna ◽  
Victor M. López-Hirata ◽  
Eduardo Oliva López ◽  
Ricardo Rodríguez Figueroa ◽  
Jorge Rodríguez Miramontes

Microstructural and mechanical characterization of Nitinol gas tungsten arc weld (GTAW) and furnace brazing (FB) welds for grade 1 titanium plates are carried out in order to study the microstructure developed after welding and its effect on the mechanical properties of welds. The GTAW process yields the highest hardness weld. The constituents for this weld consist of a dendritic structure of NiTi and NiTi2 intermetallic phases. The FB process promotes a change of the welds chemical composition due to atomic diffusion of Ti. The weld microconstituents consist of a mixture of a Ti-rich and NiTi2 eutectic and a proeutectic Ti-rich phase.


Author(s):  
Davor Stanic ◽  
Zdenka Zovko-Brodarac

Aluminum alloys are widely applied in automotive, aircraft, food and building industries. Multicomponent technical AlSi9MgMn alloy is primarily intended for high cooling rate technology. Controlled addition of alloying elements such as iron and manganese as well as magnesium can improve mechanical and technological properties of final casting in dependence from cooling conditions during solidification. The aim of this investigation is characterization of AlSi9MgMn alloy microstructure and mechanical properties at lower cooling rates than those for which this alloy was primarily developed. Thermodynamic calculation and thermal analyses revealed solidification sequence in correlation to microstructure investigation as follows: development of primary dendrite network, precipitation of high temperature Al15(Mn,Fe)3Si2 and Al5FeSi phases, main eutectic reaction, precipitation of intermetallic Al8Mg3FeSi6 phase and Mg2Si as a final solidifying phase. Influence of microstructure features investigation and cooling rate reveals significant Al15(Mn,Fe)3Si2 morphology change from Chinese script morphology at low, irregular broken Chinese script morphology at medium and globular morphology at high cooling rate. High manganese content in AlSi9MgMn alloy together with high cooling rate enables increase of Fe+Mn total amount in intermetallic Al15(Mn,Fe)3Si2 phase and encourage favourable morphology development, all resulting in enhanced mechanical properties in as-cast state.


Author(s):  
Hongyan Qi ◽  
Guixiong Gao ◽  
Huixin Wang ◽  
Yunhai Ma ◽  
Hubiao Wang ◽  
...  

The naked mole rat incisors (NMRI) exhibit excellent mechanical properties, which makes it a good prototype for design and fabrication of bionic mechanical systems and materials. In this work, we characterized the chemical composition, microstructure and mechanical properties of NMRI, and further compared these properties with the laboratory rat incisors (LRI). We found that (1) Enamel and dentin are composed of organic matter, inorganic matter and water. The ratio of Ca/P in NMRI enamel is higher than that of LRI enamel. (2) The dentin has a porous structure. The enamel has a three-dimensional reticular structure, which is more complex, regular and denser than the lamellar structure of LRI enamel. (3) Enamel has anisotropy. Its longitudinal nano-hardness is greater than that of transverse nano-hardness, and both of them are higher than that of LRI enamel. Their nano-hardness and elastic modulus increase with the increment of distance from the enamel-dentin boundary. The nano-hardness of dentin is smaller than that of enamel. The chemical composition and microstructure are considered to be the reasons for the excellent properties of NMRI. The chemical composition and unique microstructure can provide inspiration and guidelines for the design of bionic machinery and materials.


Author(s):  
Maximiano V. Ramos ◽  
Armstrong Frederick ◽  
Ahmed M. Al-Jumaily

Polymer nanocomposites offer various functional advantages required for several biomedical applications. For example, polymer nanocomposites are biocompatible, biodegradable, and can be engineered to have mechanical properties suitable for specific applications. The key to the use of polymer nanocomposites for different applications is the correct choice of matrix polymer chemistry, filler type, and matrix-filler interaction. This paper discusses the results of a study in the processing and characterization of nono-filled polymer composites and focuses on the improvement of its properties for potential biomedical applications. The experimental procedure for the preparation of nano-filled polymer composite by ultrasonic mixing is described. Different types of nanofillers and polymer matrix are studied. Effects of processing parameters such as percent loading of fillers, mixing time on the mechanical properties of the composites are discussed. Preliminary results indicate improvement in shear and flexural properties, tensile and compressive properties, were observed in the prepared composites for some processing conditions.


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