Tensile and bending behavior of sintered alloys: Experimental results and modeling

Sintered materials show a different stress-strain behavior when subjected to tensile or compressive loading, the response to compression being characterized by a higher elastic modulus, yield stress, and strain hardening rate. These differences tend to make the bending behavior somewhat more complex to analyze, particularly in the elasto-plastic field, as compared to conventional materials, having equal mechanical properties under tension and compression. As a consequence, the use of widely applied test techniques, such as the Three Point Bending (TPB), becomes more difficult for sintered materials, due to the lack of reliable analytical models capable of evaluating elasto-plastic stress-strain distribution as a function of applied load and deflection. In the present investigation, the results of uniaxial tensile-compressive and bending tests conducted on sintered ferrous alloys characterized by different microstructures and porosity are reported and briefly discussed. Then an analytical model, specifically aimed to analyze the elasto-plastic monotonic behavior of a TPB specimen made with a material having different tensile and compressive properties, is presented. Its predictions as regards load-deflection curves and elasto-plastic stress-strain distributions are compared with the results of TPB tests and of numerical (Finite Element) analysis, showing a fairly good agreement