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A step-by-step procedure to determine the quality of ingots has been developed. This procedure is built on the reduced pressure test and is designed to guide the foundrymen to decide (1) whether the lot of ingots should be accepted and/or (2) what remedial liquid metal processing should be done to bring the melt to the desired levels. A case study on two aluminum alloy A356 ingots is also presented. The results show wide variability in the initial quality of the ingots. Moreover, traditional metallographic techniques to characterize the quality from the slice of the reduced pressure test sample have been shown to provide similar results to those obtained from computerized tomography. [ABSTRACT FROM AUTHOR]

In this study, different melt treatment operations were evaluated and compared to end product's scrap rate using bifilm index (BI) method. Results clearly show that degassing with finer gas bubbles increases cleaning performance for the removal of any type of bifilms in the melt. BI method is a reliable and quick way to determine melt quality at any given time during casting process which is found to have a direct correlation with rejection rate. [ABSTRACT FROM AUTHOR]

Abstract In this study, it aimed to produce carbon fiber (CF) reinforced aluminum metal matrix composite by squeeze casting method. In order to overcome the wetting problem between the aluminum matrix and the reinforcing agent, carbon fibers were coated with Ni coating with electroless technique. Different bath pH values and hypophosphite (HP), coating durations and bath temperature were investigated. SEM, EDS and XRD methods used to determine the characterize the layers. It has been observed that increasing the pH of the bath, coating time, bath temperature and amount of hypophosphite increases the thickness of the Ni coatings on the carbon fibers. Two different thicknesses of coatings were used with different volume fractions of fiber used to reinforce the 6063 aluminum as matrix alloy. Squeeze casting process was used for the production of the composites to increase the connection between the matrix and the carbon fibers. After achieving a good bonding, three-point bending, Charpy impact, and Vickers hardness tests were carried out to investigate the difference of at the mechanical properties. It was observed from the mechanical tests that while the hardness and the three-point bending strength was increasing the impact strength was decreasing after the carbon fiber addition. Also coating, in general, helping the mechanical properties, mechanical properties of composites are badly affected by higher coating thicknesses. Highlights • Carbon fiber reinforced 6063 alloy was produced by squeeze casting method. • Ni−P were coated on carbon fibers by electroless technique to enhance the wettability. • Ni coated CF addition increased mechanical properties of 6063 alloy. • Ni thickness and distribution of fibers in the matrix affect the mechanical properties. • Incorporation of carbon fibers resulted in increased bending strength in 6063 alloy. [ABSTRACT FROM AUTHOR]

3XX series Al–Si alloys are generally used in corrosive environments open for oxidation such as rainwater and seawater. The dendrite size and characteristics of the eutectic Si are important factors determining the properties of A356 alloy. In this study, the microstructure of Sr modified A356 aluminum alloy and the changes in corrosion properties were investigated. The alloy was cast into die and sand molds to examine the effect of cooling parameters on the microstructure. Sr modification was carried out by adding four different weight percentages (0, 120, 170 and 250 ppm). Corrosion behavior of the produced alloys was investigated by two ways. One of them was electrochemical impedance spectroscopy technique and the other is potentiodynamic polarization plots that was carried out in 3.5 wt.% NaCl solution at 25 °C. The corrosion resistance of the alloy was found to be increasing as Sr content was increased which modified the morphology of the silicon in the alloy. [ABSTRACT FROM AUTHOR]