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Mr. Andreas Malmelöv
Lulea University of Technology

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0 Additive Manufacturing
0 Material Modeling
0 deformation
0 residual stresses
0 dislocation density

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Journal article
Published: 09 December 2020 in Materials
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To predict the final geometry in thermo-mechanical processes, the use of modeling tools is of great importance. One important part of the modeling process is to describe the response correctly. A previously published mechanism-based flow stress model has been further developed and adapted for the nickel-based superalloys, alloy 625, and alloy 718. The updates include the implementation of a solid solution strengthening model and a model for high temperature plasticity. This type of material model is appropriate in simulations of manufacturing processes where the material undergoes large variations in strain rates and temperatures. The model also inherently captures stress relaxation. The flow stress model has been calibrated using compression strain rate data ranging from 0.01 to 1 s−1 with a temperature span from room temperature up to near the melting temperature. Deformation mechanism maps are also constructed which shows when the different mechanisms are dominating. After the model has been calibrated, it is validated using stress relaxation tests. From the parameter optimization, it is seen that many of the parameters are very similar for alloy 625 and alloy 718, although it is two different materials. The modeled and measured stress relaxation are in good agreement.

ACS Style

Andreas Malmelöv; Martin Fisk; Andreas Lundbäck; Lars-Erik Lindgren. Mechanism Based Flow Stress Model for Alloy 625 and Alloy 718. Materials 2020, 13, 5620 .

AMA Style

Andreas Malmelöv, Martin Fisk, Andreas Lundbäck, Lars-Erik Lindgren. Mechanism Based Flow Stress Model for Alloy 625 and Alloy 718. Materials. 2020; 13 (24):5620.

Chicago/Turabian Style

Andreas Malmelöv; Martin Fisk; Andreas Lundbäck; Lars-Erik Lindgren. 2020. "Mechanism Based Flow Stress Model for Alloy 625 and Alloy 718." Materials 13, no. 24: 5620.

Journal article
Published: 29 December 2019 in Metals
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Additive manufacturing is the process by which material is added layer by layer. In most cases, many layers are added, and the passes are lengthy relative to their thicknesses and widths. This makes finite element simulations of the process computationally demanding owing to the short time steps and large number of elements. The classical lumping approach in computational welding mechanics, popular in the 80s, is therefore, of renewed interest and is evaluated in this work. The method of lumping means that welds are merged. This allows fewer time steps and a coarser mesh. It was found that the computation time can be reduced considerably, with retained accuracy for the resulting temperatures and deformations. The residual stresses become, to a certain degree, smaller. The simulations were validated against a directed energy deposition (DED) experiment with alloy 625.

ACS Style

Andreas Malmelöv; Andreas Lundbäck; Lars-Erik Lindgren. History Reduction by Lumping for Time-Efficient Simulation of Additive Manufacturing. Metals 2019, 10, 58 .

AMA Style

Andreas Malmelöv, Andreas Lundbäck, Lars-Erik Lindgren. History Reduction by Lumping for Time-Efficient Simulation of Additive Manufacturing. Metals. 2019; 10 (1):58.

Chicago/Turabian Style

Andreas Malmelöv; Andreas Lundbäck; Lars-Erik Lindgren. 2019. "History Reduction by Lumping for Time-Efficient Simulation of Additive Manufacturing." Metals 10, no. 1: 58.