Estimation of the mechanical properties of metallic materials by means of the small punch test

It is sometimes very convenient to use miniature tests for the mechanical characterization of materials, making use of very small specimens which may be extracted from the components during their normal service life. One of these tests is the small punch test (SPT). Nevertheless, different expressions for estimating the tensile and fracture properties of metallic alloys by means of the small punch test (SPT) were proposed and their applicability was assessed in this paper after experimental testing a wide range of metallic materials and the application of a numerical model developed to study the effect of specimen thickness on these proposals. The best estimation of the yield strength was obtained employing the SPT yield load assessed as the crossing point between the SPT curve and a straight line parallel to the initial slope of the graph, with an offset displacement of t/10. The most suitable relationship for estimating the ultimate tensile strength was obtained by dividing the maximum SPT load by the product of the thickness and the displacement at maximum load (d(m)). However, a suitable relationship between the SPT displacement at maximum load and the tensile elongation was not obtained in the investigated materials, but it was demonstrated that the fracture toughness of non-brittle steels can be estimated from biaxial fracture strain (epsilon(qf)), when epsilon(qf) > 0.8. (c) 2013 Elsevier B.V. All rights reserved.