ICAMS / Interdisciplinary Centre for Advanced Materials Simulation

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CPFEM modeling of porosity reduction in an as-cast Ni-base single crystal superalloy under HIP

Date: 25.03.2015
Place: Gordon Research Conference Physical Metallurgy 2015, Maine, USA

Anxin Ma
Inmaculada Lopez-Galilea, Ruhr-Universität Bochum, Bochum, Germany
Werner Theisen, Ruhr-Universität Bochum, Bochum, Germany
Alexander Hartmaier

The excellent performance of Ni-base single crystal superalloys at high temperature comes from the precipitate strengthening by coherent cuboidal precipitates homogeneously distributed in the matrix and the solid solution strengthening by adding a high concentration of refractory elements. However, a stronger dendritic segregation during solidification and pores accumulation in the interdendritic region during an extensive homogenization tend to occur, which deteriorates the mechanical properties. In order to heal these micropores, hot isostatic pressing (HIP) as an advanced thermal treatment is utilized, which combines plastic deformation, creep and diffusion bonding to homogenize the alloy composition through an appropriate pressing and high temperature. As the costs of single crystal superalloys and HIP are high, it is necessary to understand the porosity reduction in this process by modeling to optimize the HIP parameters and reduce the expense. Our CPFEM simulations show that: Pore shape strongly affects the pore shrinkage in rate and local deformation; as pore schrinkes, the hetergenity of stress decreases, while the heterogenity of deformation increases.

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