Using high temperature tensile testing data to analyze hot formability of Sn-5Sb alloy: instability and critical damage criteria

In a general overview, hot workability defined by relative ease of deformation during thermomechanical processing depends on localized distribution of stress, strain, temperature and strain rate. In the current research, unsteady flow and formability behavior of Sn-5Sb alloy was investigated using hot tensile tests carried out on the homogenized cast material. To do this, occurrence of instability and evolution of microstructure of such alloy were studied taking the advantage of various instability criteria for hot deformation routes. The output of the models which can be categorized in analytical and empirical approaches were studied in detail and their performance and relative conservativeness and significance were compared. For a better clarification and cognitive comparison of obtained results, hot deformation processing maps were established based on data offered by diverse instability criteria. In addition, an attempt was made for determining critical damage values for this alloy during hot deformation considering several ductile fracture criteria. Taking the advantage of hot tensile data, the tests were then simulated for obtaining required characteristic stress and strain values to be used for evaluating ductile fracture. Simulations were performed by means of finite element method (FEM) in a three-dimensional state of strain in deformation zone. The results exhibit that critical damage values strongly depend on strain rate and temperature and is in accordance with flow instability variation in this alloy.