Simulation of weld solidifiation cracking in varestraint tests of alloy 718

Selected peer reviewed papers from the 12th International Seminar Numerical Analysis of Weldability

Document identifier: oai:DiVA.org:ltu-75740
Access full text here:10.3217/978-3-85125-615-4-26
Keyword: Engineering and Technology, Materials Engineering, Other Materials Engineering, Teknik och teknologier, Materialteknik, Annan materialteknik, Solidification cracking, Hot cracking, Varestraint testing, Computational Welding Mechanics, Alloy 718, Material Mechanics, Materialmekanik
Publication year: 2019
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SDG 9 Industry, innovation and infrastructure
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Abstract:

Several nickel-based superalloys are susceptible to weld solidification cracking. Numerical simulation can be a powerful tool for optimizing the welding process such that solidification cracking can be avoided. In order to simulate the cracking, a crack model inspired by the RDG model is proposed. The model is based on a crack criterion that estimates the likelihood for a preexisting pore in a grain boundary liquid film to form a crack. The criterion depends on the thickness and the liquid pressure in the grain boundary liquid film, as well as the surface tension of the pore. The thickness of the liquid film is computed from the macroscopic mechanical strain field of an FE model with a double ellipsoidal heat source. A temperature-dependent length scale is used to partition the macroscopic strain to the liquid film. The liquid pressure in the film is evaluated using a combination of Poiseuille parallel plate flow and Darcy’s law for porous flows. The Poiseuille flow is used for the part of the grain boundary liquid film that extends into the region with liquid fraction less than 0.1, while Darcy’s law is used for the rest of the liquid film that extends into the regions with liquid fraction greater than 0.1. The proposed model was calibrated and evaluated in Varestraint tests of Alloy 718. Crack location, width, and orientation were all accurately predicted by the model.

Authors

J. Draxler

Luleå tekniska universitet; Material- och solidmekanik
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J. Edberg

Luleå tekniska universitet; Material- och solidmekanik
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J. Andersson

University West, 46132 Trollhättan, Sweden
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L-E. Lindgren

Luleå tekniska universitet; Material- och solidmekanik
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