No abstract

Composite metal products consisting of two different alloys can be prepared by a few methods. Cast bonding is one of these methods. The bond between the two materials forms primarily in the solid state by diffusion, after casting of a cladding alloy on to the preheated surface of a substrate. In this work, a ferritic stainless steel was used as the substrate, and, gray iron or nodular iron as the cast alloy. It was found that these two alloys can be successfully joined, and under specific casting parameters, a very strong bond develops between the two alloys. Bond strength was found to be greater than that of gray iron. Microstructural zones on both sides of the bond were studied. It was found that diffusion of chromium into iron and diffusion of carbon into steel is significant in bonding. Chemical composition changes due to diffusion was studied by EDS. Fe-Cr-Mn carbides were formed at the bond during the casting. These carbides were largely eliminated by a subsequent high temperature heat treatment.

Porous metal materials are a new class of materials with low densities, large specific surface, and novel physical and mechanical properties. Their applications are extremely varied: for light weight structural components, for filters and electrodes, and for shock or sound absorbing products. Recently, interesting foaming technology developments have proposed metallic foams as a valid commercial chance; foam manufacturing techniques include solid, liquid, or vapor state methods. The foams presented in this study are produced by Melt Gas Injection (MGI) process starting from melt aluminum. The aim of this investigation is to obtain complex foamed aluminum parts in order to make the MGI more flexible. This new method, called MGI-mould process, makes possible to produce 3D-shaped parts with complicated shape or configuration using some moulds obtained by traditional investment casting process.