Designing laminated metal composites for tensile ductility

• Survey of parameters dictating the ductility of strain-rate sensitive materials.
• Graph summarizes their influence on the ductility of laminated metal composites.
• Promising materials combinations identified.

This contribution draws practical implications of a recently published estimation of the tensile ductility in laminated composites made of two ductile materials, typically metals or alloys, which harden as both the strain and the strain-rate increase. To this end, the literature is surveyed to collect values for the strain hardening exponent, the strain-rate sensitivity and the strength constant for a wide range of engineering metals and alloys. Material combinations that might produce ductile laminated metal composites are then examined in light of the data and theory. A simple graph is proposed, which gives a direct reading of the predicted elongation to failure of composites containing equal volume fractions of any two materials among those surveyed. The resulting plots show material combinations in which a more ductile material can significantly increase, within a laminated metal composite (LMC), the tensile elongation of a less ductile material. In this role, 304 stainless steel and commercial purity iron emerge as sensible possibilities.