A study on the variation in tensile ductility of porous sintered iron

A model based on Irwin's approach to elastic-plastic deformation was applied to predict the tensile ductility of a sintered iron. The evaluation of this model using experimental results for porous sintered iron showed that tensile ductility depends not only on the pore volume fraction, but also the pore size and the mechanical properties of the matrix. It was shown that this model agrees well with experimental data and resolves some of the discrepancies of the Brown-Embury model. This model suggested that the ductility of the porous metal can be improved by actively controlling the metallurgical parameters, such as the mechanical properties of the matrix and the pore size. It can be seen that the fracture true strain of the base metal has the same effect as the change in pore radius, because it acts as a linear function in the ductility prediction of porous iron. On the other hand, the σ_y^m/ΔK_{th, eff} ratio varies from the quadratic function. The calculation results based on this model show that effect of the change in the σ_y^m/ΔK_{th, eff} ratio on the ductility of the porous metal is greater than the effect of the change in the pore radius and fracture true strain. This model also shows it is possible to improve tensile ductility in porous metals by controlling the mechanical properties of the base metal or controlling the pore radius, in addition to reducing the pore volume fraction. In other words, increasing the ductility of the porous metal is possible by increasing the pore radius, or using a base metal with high yield strength and low σ_y^m/ΔK_{th, eff,}or using a base metal with high fracture true strain.