Abstract
A review of the available literature indicates that the development of metal-reinforced castings present intriguing prospects but carry inherent challenges owing to differences in thermal coefficients, chemical affinities, diffusion issues and the varying nature of intermetallic compounds. It is supported that pressure application during solidification may favorably influence the dynamics of the aforementioned issues; nevertheless, not only certain limitations have been cited, but also some pressure and process regimes have not yet been investigated and optimized. This work employs the pressure-assisted approach for bimetallic steel-reinforced aluminum composite castings at a low-pressure regime and thoroughly investigates the role of three process parameters, namely pouring temperature (800–900 °C), pressure (10–20 bars) and holding time (10–20 s), for producing sound interfaces. The Taguchi L9 orthogonal array has been employed as the Design of the Experiment, while dominant factors have been determined via analysis of variance and the grey relational analysis multi-objective optimization technique. Supplementary analysis through optical micrographs, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) has been utilized to quantify interfacial layer thicknesses and to study microstructural and compositional aspects of the interface. Nano-indentation tests under static and dynamic loading have also been performed for mechanical strength characterization. It has been found that uniform interfaces with verifiable diffusion are obtainable, with the pouring temperature being the most influential parameter (percentage contribution 92.84%) in this pressure regime. The experiments performed at optimum conditions of pouring temperature, applied pressure and holding time produced a ~328% thicker interface layer, 19.42% better nano-hardness and a 19.10% improved cooling rate as compared to the minimum input values of the said parameters.
Highlights
Instead of using a mesh structure, rods were employed for reinforcement so as to focus on interface development at different experimental conditions while preventing any potential adversities arising from complicated flow patterns
The typical intermetallics found in the Al-Fe interface, their mechanical attributes of being brittle and hard and their reported nano-hardness values, which are comparable to the ones obtained in current work, effectively explain the current findings and confirm that the current results conform with the available literature in this regard
In the context of developing aluminum–steel bimetallic composite castings via a pressure-assisted approach, the following conclusions may be drawn from the presented work:
Summary
GRA, which is a powerful analysis technique, and the use of Taguchi orthogonal array is an established approach that helps to arrive at the optimum settings of parameters with a lesser number of experiments, as may be required for full factorial experiments [42]. For post-experimentation analysis, samples for the microstructure, SEM analysis and mechanical characterization were extracted from the castings. Interface SEM (Inspect S-50 of Thermo Fisher Scientific, Hillsboro, OR, USA) images were taken at a magnification of 3000× for an in-depth examination of compositional and microstructural details.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
