Effect of Pressurization and Annealing on Hole Expansion

Due to the continuous push toward environmental regulations to reduce the impact on the environment, more sustainable manufacturing is in demand. Easily available material like iron-carbon based alloys are denser but exhibit higher strength and good formability. Alternatively, low dense materials have the potential to reduce the weight, but they lose the "easy-to-deform"spot. In addition, the traditional method to characterize the material is not sufficient to capture the material model which would accurately predict the complex nature of deformation. Thus, the present study is focused on how to make the material more deformable in the process by evaluating the parameters in deformation through the hole expansion process. For this study, four tests were chosen, namely hemispherical dome test, cylindrical tool test, conical tool test, and biaxial test. Except the biaxial test, all tests use the rigid tool punch to deform the hole. The cruciform specimen with a center hole was used to make the sample, which fits in all the considered tests. Force-displacement curves were plotted and discussed. In addition, tests were also performed on annealed materials to understand the hole expansion in ductile material. Based on the results it was observed that biaxial tests do not provide any pressurization effect and all tests which include the rigid tool to deform the hole doe. Due to the pressurization effect, the hole was expanded more. It was also noted that the hole expansion was more in ductile material and pressurization effect increases with ductile material.