Study on Tensile Behavior of Small Size Specimen of A508-III Steel Based on Finite Element Aided Testing Method

In order to overcome the influence of size effect brought about by the reduction in the size of tensile specimen, the tensile properties have been investigated for small size specimens of A508-III steel in this paper. The small size specimens of A508-III steel with varying grain sizes and specimen thicknesses were prepared by altering the heat treatment temperature, and their tensile tests were conducted at room temperature. The effects of grain size and thickness on the tensile mechanical properties of small size specimens were analyzed and the underlying mechanism of the potential tensile size effect was revealed. The results indicate that, due to the changes in the thickness and grain size of small size specimens, the tensile mechanical property exhibits an obvious size effect. A Swift mechanical constitutive model considering size effects was developed by introducing influence parameters that comprehensively characterize the specimen feature size and grain size effects. The ductile damage evolution parameters of the specimens were determined using the finite element aided testing (FAT) method, and the error between numerical and experimental results was less than 3%. Based on the established mechanical constitutive model, the tensile mechanical properties of the small size specimens were predicted using the finite element method, and the normalized models of their yield strength and tensile strength were constructed, so as to provide reference for the engineering application of small size specimens.