Influence of strain state in mechanical behaviour of aluminium alloys using the Small Punch Test

• Influence of two strain states in mechanical behaviour using SPT studied.
• Different levels of tensile and compressive plastic strain tested on SPT specimens.
• Conventional correlation between σy and Py becomes obsolete with plastic deformation.
• New correlations for tensile and compressive strain states developed.
• Estimation of σy on any plastically deformed area with single SPT specimen.

The Small Punch Test (SPT) basically consists of deforming a miniature specimen, whose edges are firmly gripped by a die, using a high strength punch. This test was developed in the eighties and has since been used successfully on numerous occasions in those cases where there is not sufficient material to carry out standard tests to obtain the mechanical properties of materials. In recent years, it has been used successfully to determine the yield strength evolution in any area of stamped aluminium alloy components.These stamped components are subject to different kinds of plastic deformation during the stamping process. The main objective of this paper is to analyze the influence that the type of deformation reached during the stamping process has on the mechanical behaviour of the material. Furthermore, for each kind of strain, the yield load in the SPT will be related to yield strength to provide a unique valid expression to evaluate the hardening of the material.

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