About this Abstract |
| Meeting |
MS&T26: Materials Science & Technology
|
| Symposium
|
Fracture of Steels: New Approaches to Modeling and Experimental Characterization
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| Presentation Title |
Multiphase-Field Modeling of Thermo-Chemo-Mechanical Phenomena for Solidification Cracking in Steels |
| Author(s) |
Muhammad Umar, Nishant Prajapati, Thea Kannenberg, Daniel Schneider, Britta Nestler |
| On-Site Speaker (Planned) |
Muhammad Umar |
| Abstract Scope |
Solidification cracking in laser beam welding of austenitic stainless steels arises from thermochemical gradients and mechanical stresses in the mushy zone. A chemo-thermo-elastic framework predicts stress and strain localization in the dendritic microstructure after solidification simulations of a quaternary Fe-Cr-C-Ni alloy, providing insight into fracture initiation at the weld centerline.
A grand-potential multiphase-field model coupled with CALPHAD thermodynamics predicts the chemical gradients. This is used by solid mechanics to resolve chemical, thermal, and mechanical driving forces at the microscale. Simulations employ a 1.8% transverse strain validated against digital image correlation (DIC) measurements from in-situ weldability tests.
Parametric studies show that dendrite growth angle dominates stress localization: low angles generate interdendritic liquid bands that concentrate von Mises stresses. Higher solidification velocity increases liquid film thickness; higher thermal gradients reduce mushy zone strain. Solid-solid centerline boundaries represent critical fracture sites, explaining experimentally observed centerline solidification cracks and guiding process-parameter optimization. |