Quasi-static and dynamic mechanical performance of glass microsphere- and cenosphere-based 316L syntactic foams

Syntactic foams are produced by adding hollow particles to a solid matrix material. So far, few processes exist that allow manufacturing of such materials using steel matrices. Extremely versatile in this respect are powder metallurgical processes like metal powder injection moulding (MIM), which facilitate usage of different matrix alloys in combination with micro scale fillers. Existing studies on such materials mostly concentrate on quasi-static properties, with Fe99.7 matrices combined with glass microspheres as one exception for which dynamic data has been published. The present work extends the range of matrix materials by summarizing experimental studies on 316L stainless steel foams using glass microspheres as well as cenospheres for the role of introducing porosity. Quasi-static tensile and compressive properties have been evaluated at different density levels - namely 5 and 10 wt.-% of microsphere addition - and are contrasted to dynamic performance as determined by means of impact testing and Split Hopkinson Pressure Bar (SHPB) techniques. Failure mechanisms of the materials are discussed in view of the experimental results, evaluations of the foams' structural characteristics and comparison with the aforementioned existing quasi-static and dynamic data on Fe99.7 syntactic foams. Furthermore, performance is qualitatively and quantitatively compared to other types of 316L stainless steel matrix foams, such as the so-called composite metal foams (CMF) investigated by Rabiei and Vendra (2009).