How Slight Solidification Rate Variations within Cast Plate Affect Mechanical Response: A Study on As-Cast A356 Alloy with Cu Additions

The present work investigates a narrow range of secondary dendrite arm spacing (SDAS), in an as-cast A356 alloy with and without copper (Cu) additions. Cu was added to the base A356 alloy melt to reach the target concentration of 0.5 and 1 wt.%. Samples were selected from 3 different positions within the cast plate, offering 30, 35, and 40 μm SDAS variants. Tensile curves revealed a strong influence between the specimen cutting position and strength, with a pronounced effect in the Cu-containing alloys. Hardness measurements did not confirm the tensile response; hence, to understand the phenomenon, microstructural features have been investigated in detail. Eutectic silicon (Si) particle equivalent diameter (ED) size decreased from the top (T) to the bottom (B) position of the cast. Eutectic Si particle surface area (A%) was found to be denser at the B as compared to the T and simultaneously in the Cu-containing alloy as compared to the Cu-free reference alloy. Backscattered electron (BSE) images were employed to investigate the nature of the Cu-rich intermetallic phases. In conclusion, electrical conductivity measurements were performed to confirm the trends observed.

Dependence Of The Structure And Magnetic Properties Of Cast Plate-Shaped Nd60Fe30Al10 Samples On Their Thickness

The hard magnetic Nd-Fe-Al alloys are inferior to Nd-Fe-B magnets as far as the magnetic properties are concerned, but their great advantage is that they need no additional annealing to achieve good magnetic properties. These properties depend on the cooling rate from the melting state, and on the thickness of the sample - the best values are achieved at the quenching rates at which the samples have a thickness of 0.3-2 mm. The present study is concerned with the correlation between the magnetic properties of the plate-shaped Nd60Fe30Al10 samples and their size - thickness. Two casting ways: with the melt stream perpendicular direction and parallel to the surface of the plates were used. The plates were produced by pressure casting and suction casting. The studies have shown that the cooling rates depends on local propagation on liquid metal in the mold resulting in heterogeneity of structure and properties.

Shape Accuracy of Iron Precision Castings in Terms of Ceramic Moulds Physical Properties Anisotropy

While analyzing shape accuracy of ferroalloy precision castings in terms of ceramic moulds physical anisotropy, low-alloy steel castings ("cover") and cast iron ("plate") were included. The basic parameters in addition to the product linear shape accuracy are flatness deviations, especially due to the expanded flat surface which is cast plate. For mentioned castings surface micro-geometry analysis was also carried, favoring surface load capacity tp50 for Rmax = 50%. Surface load capacity tp50 obtained for the cast cover was compared with machined product, and casting plate surface was compared with wear part of the conveyor belt. The results were referred to anisotropy of ceramic moulds physical properties, which was evaluated by studying ceramic moulds samples in computer tomography equipment Metrotom 800

Quantification and Statistical Analysis of Microstructural Features in As-Cast Ti-6Al-4V Titanium Alloy

Based on microstructure of as-cast Ti-6Al-4V titanium alloy, an image processing to simplify model of β grain size, α lamella space was developed and a quantitative statistical method of β grain size, α lamella space in two-phase titanium alloys was established, with which β grain size and α lamella space of as-cast Ti-6Al-4V titanium alloy with different plate thickness were analyzed. The relationship between β grain size, α lamellar space and cast plate thickness was discussed. The results show that β grain size and α lamellae thickness nearly linearly increase as plate thickness increasing. β grain size has normal distribution and with cast plate thickness increasing, the dispersion gets larger.

Study on Processing Properties of Epoxy Resin System in VARI

As a low cost moulding technology, VARI is widely used to produce advanced composite materials. At the same time, the particularity of VARI process make it have particular requirements on resin system. Epoxy resin system attracts extensive attention because of its good process performance. Curing reaction and rheological behavior of epoxy resin system were studied by DSC and viscosity experiments. The results showed that resin viscosity decreased from 2600 mPa•S at 15°C to 600mPa•S at 40°C . Viscosity of resin system rose about 0.5Pa•s within the first 2h. Gel time shortened dramatically when the temperature exceed 60°C. the curing temperature is 60°C be based on DSC curve and gel time-temperature curve. Resin cast plate of epoxy resin system has good mechanical properties of compression strength.

Simplified Calculation of Temperature Stress of Cast Plate in Frame Structure

The impact of temperature stress cannot be ignored in actual project. Single-frame shear wall structure of two-dimensional plane has been simplified in this paper. Fixed point of displacement under the influence of the temperature is determined in structure. Model for Calculating is given. Temperature stress of frame - shear wall cast plate is found by matrix method.