Optimization of the t/10 offset correlation method to obtain the yield strength with the Small Punch Test

Abstract

The Small Punch Test (SPT) was developed as an alternative test to evaluate the mechanical properties of materials from a small material volume. Although the SPT is close to its standardization as a mechanical testing method, there are many methodologies for the estimation of the different mechanical properties. All of them are based on the use of a correlation equation to link the SPT and the estimated mechanical property. The scattering of these correlation methods is generally great enough to make it necessary to delve deeper into the understanding of the physical behavior of the SPT.

This investigation was based on previous numerical studies related with the multi-dependency with more than one mechanical property of the correlation methods for the yield strength estimation. Specifically, an optimization of the t/10 offset correlation method was designed introducing the minimum slope Slopemin of the zone III of the SPT curve in the correlation equation. This optimized t/10 offset method showed a significant reduction of the scattering between its regression surface and the material data. After completing this numerical analysis, experimental tests (tensile and SPT tests) were performed to validate the new method.