Metal Foam Stops .50 Caliber Rounds as Well as Steel – At Less Than Half the Weight


Matt Shipman, June 5, 2019

“CMF is a foam that consists of hollow, metallic spheres – made of materials such as stainless steel or titanium – embedded in a metallic matrix made of steel, titanium, aluminum or other metallic alloys. In this study, the researchers used steel-steel CMF, meaning that both the spheres and the matrix were made of steel.”

“The CMF armor was less than half the weight of the rolled homogeneous steel armor needed to achieve the same level of protection,” says Afsaneh Rabiei, corresponding author of a paper on the work and a professor of mechanical and aerospace engineering at North Carolina State University. Rabiei, the inventor of CMF, has spent years developing and testing CMF materials.”

Mitch: This material is amazing, being able to take these extreme impact forces at less than half the weight of comparable homogenous steel has huge implications for my research. One of the greatest concerns expressed by firefighters in my research was the weight of the tools involved. Being able to use metal foam for the majority of a tool, with solid inserts for mass, would allow for tools of reduced weight. Additionally it would allow for new shapes and idealized mass distributions in striking tools. By repositioning mass through the selective use of inserts and various foam compositions, lighter tools with greater impact are possible. Also the surface finish of these foam are inherently grippy making for better handles with less post processing of any tools made from them.