In-situ surface modification of high-silicon ductile cast iron produced by sand mold casting

Corrosion is a critical and common problem in cast iron castings used in industry. To improve the corrosion resistance different strategies could be used, however, most of these methods lead to expensive casting.

In this work, a surface modification layer was produced by in situ casting on high-silicon ductile cast iron using “Duplex powder”. The microstructure of the generated surface layer was characterized by using optical microscopy (MO), scanning electron microscopy (FE-SEM), electron backscatter diffraction (EBSD) and the phases were identified by X-ray diffraction.

The corrosion behavior of the samples was analyzed by potentiodynamic polarization test in 3.5% NaCl solution. The Vickers hardness measurements were performed to determine the properties of the modified surface layer. The results showed that the layer formed consists of carbides, ferrite, and -Fe. The modified surface layer created has higher hardness and better corrosion resistance compared with the high-silicon ductile cast iron. EBSD characterization shows the microstructure with bimodal grain size.