Processing and characterization of dual phase steel foam

Abstract

Porous materials featuring cellular structures are known to have many interesting combinations of physical and mechanical properties. Some of them have been extensively used in the transportation field (i.e. balsa wood). Steel foams presented promising theoretical properties for both functional and structural applications in transportation, but processing of such a kind of foams is complex due to their high melting point. Recently a technique for processing Cu-based alloys open-cell foams through the molten metal infiltration of a leachable bed of amorphous SiO 2 particles was proposed. A variation of the proposed technique that uses SiC particles as space holder is now presented and was recently successfully applied for dual phase steel foam processing. Results from a processing of dual phase DP500 steel foams, including some morphological, micro-structural and mechanical characterization, are here presented.Keywords: Dual phase steel, cellular metals, metal foams, silicon carbide. INTRODUCTIONBased on their particular morphology, cellular metals and alloys offer an interesting mix of physical-chemical and mechanical properties. That makes these materials very attractive both for structural and functional applications [1,2]. Cellular metals are now produced by several processes, including molten metal infiltration of a leachable bed of solid particles, also known as space holder [3,4]. A recent work introduced the use of amorphous SiO 2 (silica-gel) beads as space holder for open-cell Cu-based foam processing through molten metal infiltration [5]. Once infiltrated, SiO 2 particles are dissolved by a wet solution of hydrofluoric acid (HF). Unfortunately this technique is not applicable for processing of steel foams, mainly due to the high melting point of steels (~1500 ºC). For overcoming this limitation it is proposed to use beta-SiC as space holder. SiC can withstand the infiltration efforts till 1800 ºC without problems and can be also dissolved by aqueous HF. On the other hand, the chemical stability of SiC at such temperatures diminishes the possibility of interaction among the molten metal and the space holder. Following this route highly homogeneous dual-phase steel foams featuring opened cell structure were processed. The proposed methodology is based on cheap commercial consumables and simple technology, focusing on low cost foams with interesting cost/benefit ratios. Based on the acquired scientific literature the proposed route represents the first attempt for applying SiC as space holder for steel foam processing.Open-celled metal foams typically show low density, high surface vs. volume ratio, low stiffness and permeability to fluid flow [2,3]. Based on these features they represent a suitable opportunity for the production of several components, i.e. elements to be inserted in sandwich systems, vibration damping components, filters, substrates for catalytic reactions, electrodes, porous media for biomedical applications, heat exchanging elements, etc [1,4]. Dual phase steels are much used i...

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