{"id":1398,"date":"2022-02-16T16:28:50","date_gmt":"2022-02-16T15:28:50","guid":{"rendered":"https:\/\/www.for5134.science\/?page_id=1398"},"modified":"2026-09-11T08:07:29","modified_gmt":"2026-09-11T06:07:29","slug":"teilprojekt-tp6","status":"publish","type":"page","link":"https:\/\/www.for5134.science\/en\/teilprojekte\/teilprojekt-tp6\/","title":{"rendered":"Sub-project 6 &#8211; Microstructure simulation of solidification in the weld seam"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">Motivation<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Solidification cracking during laser beam welding (LBW) is a complex, multiscale and multiphysical phenomenon that originates in the microstructure. Sub-project <strong>TP6<\/strong> investigates the formation and propagation of solidification cracks at the microscale, using chemo-thermo-mechanical modelling. With a strongly coupled phase-field model, the evolution of stresses and strains during dendritic solidification and the subsequent solid-state transformations is predicted.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In the first funding phase, TP6 focused on austenitic stainless steels. However, these steels generally show good resistance to solidification cracking, which makes it difficult to directly correlate theoretical predictions with experimentally observed, cracked microstructures. For the second funding phase, TP6 therefore focuses on <strong>Ni-based superalloys<\/strong>. These alloys exhibit a significantly higher susceptibility to solidification cracking and offer a wide range of compositional variations and solidification behaviours, making them far better suited for an in-depth study of the underlying relationships between microstructure and properties.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Results from the first funding phase<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Building on the work of the first phase, TP6 established several key results that form the foundation for the second phase:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>A <strong>CALPHAD-based parabolic Gibbs-energy model<\/strong> for the quaternary Fe-C-Cr-Ni system was formulated and validated. It reproduces the CALPHAD thermodynamics in the relevant solidification range with an accuracy of over 99 %.<\/li>\n\n\n\n<li><strong>Validated 2D and 3D phase-field simulations<\/strong> of dendritic growth reproduced the dendritic morphology and the microsegregation of the critical alloying elements (C, Cr, Ni), including the transition from columnar to cellular dendrites and the formation of residual interdendritic liquid.<\/li>\n\n\n\n<li>The contribution of <strong>thermal and chemical (segregation-induced) inelastic strains<\/strong> to the local stress state was quantified, and an initial assessment of the probability of cracking was performed based on these thermochemical inelastic strains.<\/li>\n\n\n\n<li>For high-throughput solidification studies, a <strong>fully automated Kadi4Mat \/ KadiStudio workflow<\/strong> was developed that includes CALPHAD fitting, analysis of the weld pool geometry, setup of HPC simulations and automated post-processing of characteristic microstructural parameters (dendrite tip radius, arm spacing, tip velocity, etc.).<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Objective<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The overarching goal of the second phase is to improve the understanding and quantitative prediction of solidification cracking at the microscale in Ni-based superalloys. The main objectives are as follows:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Extension of the strongly coupled chemo-thermo-mechanical phase-field model through a <strong>separate treatment of interstitial and substitutional elements<\/strong> (e.g. boron, carbon, nitrogen) and through a <strong>simulated temperature evolution<\/strong>, including the release of latent heat.<\/li>\n\n\n\n<li>Modelling of the <strong>\u03b3 \u2192 \u03b3\u2032 solid-state transformation<\/strong> and the associated transformation strains, which are decisive for the mechanical stability and crack susceptibility of Ni-based superalloys.<\/li>\n\n\n\n<li>Determination of the <strong>effective, temperature-dependent mechanical properties<\/strong> at the micro- and grain scale, based on the simulated microstructures.<\/li>\n\n\n\n<li>Modelling of the <strong>crack nucleation and propagation during solidification<\/strong>, using anisotropic critical energy release rates that depend on the depletion zone, as well as the derivation of statistical crack descriptors (crack distribution, crack fraction and crack formation rate).<\/li>\n\n\n\n<li>Integration of all steps into <strong>Kadi4Mat high-throughput workflows<\/strong>, in conjunction with AI and machine learning methods (e.g. Bayesian optimisation), to identify optimal alloy compositions and process parameters for minimising hot cracks.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Work plan<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The project is divided into five interrelated work packages (WP):<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Model extension and parameterisation<\/strong> \u2013 CALPHAD-based Gibbs energy functions for the Ni-based alloy, grouping of chemically similar elements into a quaternary configuration, separate treatment of interstitial and substitutional elements, and coupling of the simulated temperature evolution (input from TP3 \/ TP4).<\/li>\n\n\n\n<li><strong>Automated execution of solidification simulation studies<\/strong> \u2013 Adaptation of the Kadi4Mat workflow to the Ni-based system, high-throughput dendritic solidification studies, and automated determination of morphological descriptors (together with TP4 \/ TP7).<\/li>\n\n\n\n<li><strong>Modelling of the \u03b3 \u2192 \u03b3\u2032 solid-state transformation<\/strong> \u2013 Prediction of the precipitation microstructure and transformation-induced stresses at the micro- and grain scale.<\/li>\n\n\n\n<li><strong>Loading simulation studies and effective mechanical properties<\/strong> \u2013 Elasto-plastic (J2 plasticity, Voce hardening) simulations to derive effective, anisotropic mechanical properties and local stress concentrations from the microstructures.<\/li>\n\n\n\n<li><strong>Modelling of solidification cracking<\/strong> \u2013 A research group-wide work package in which a multiphase-field model for crack propagation is applied and extended to identify critical influencing factors and determine crack initiation criteria for the LBW of Ni-based superalloys.<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">Together, the workflows of WP2, WP3 and WP5 form a <strong>digital twin<\/strong> that can be used to analyse how the physical boundary conditions influence the critical factors in solidification cracking.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Interaction with the other sub-projects<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">TP6 receives thermal and mechanical boundary conditions from <strong>TP3<\/strong> and <strong>TP4<\/strong>, and grain-scale microstructures from <strong>TP3<\/strong>. In return, TP6 supplies microscale morphological information and effective, temperature-dependent mechanical properties to <strong>TP4<\/strong> and <strong>TP5<\/strong>, and parameterises the grain-scale solidification model in <strong>TP3<\/strong>. Simulated microstructures are compared with experimental results from <strong>TP1<\/strong> and <strong>TP2<\/strong>, and all workflows, data and metadata are managed via <strong>TP7<\/strong> (Kadi4Mat), following the FAIR principles.<\/p>\n\n\n\n<div style=\"height:15px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n<div class=\"wp-block-image wp-image-1945 size-large\">\n<figure class=\"aligncenter\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"512\" src=\"https:\/\/www.for5134.science\/files\/2026\/09\/grapAbstract_english-1024x512.png\" alt=\"\" class=\"wp-image-2867\" srcset=\"https:\/\/www.for5134.science\/files\/2026\/09\/grapAbstract_english-1024x512.png 1024w, https:\/\/www.for5134.science\/files\/2026\/09\/grapAbstract_english-768x384.png 768w, https:\/\/www.for5134.science\/files\/2026\/09\/grapAbstract_english-300x150.png 300w, https:\/\/www.for5134.science\/files\/2026\/09\/grapAbstract_english.png 1152w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\"><strong>Figure A:<\/strong> Graphical abstract showing the length scale relevant to TP6, within the research group: The dendritic solidification front in the mushy zone of the LBW weld, investigated in a thermo-chemo-mechanical environment at the microscale.<\/figcaption><\/figure>\n<\/div>\n\n\n<div style=\"height:31px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h4 class=\"wp-block-heading\">Sub-project management<\/h4>\n\n\n\n<div class=\"wp-block-media-text is-stacked-on-mobile\" style=\"grid-template-columns:15% auto\"><figure class=\"wp-block-media-text__media\"><img loading=\"lazy\" decoding=\"async\" width=\"150\" height=\"180\" src=\"https:\/\/www.for5134.science\/files\/2022\/02\/bild_britta-nestler-e1644499020119.jpg\" alt=\"Bild von Frau Professor Doctor als Mitglied im Leitungsteam des Teilprojektes 6 und 7\" class=\"wp-image-1278 size-full\" \/><\/figure><div class=\"wp-block-media-text__content\">\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/www.h-ka.de\/en\/about-hka\/organization-people\/staff-search\/person\/britta-nestler\">Prof. Dr. rer. nat. Britta Nestler<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\" style=\"font-size:16px\">Hochschule Karlsruhe University of Applied Sciences<br>Faculty of Computer Science and Business Information Systems<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"mailto:michael.rethmeier@bam.de\"><\/a><a href=\"mailto:matthias.markl@fau.de\"><\/a><a href=\"mailto:j.schroeder@uni-due.de\"><\/a><a href=\"mailto:axel.klawonn@uni-koeln.de\"><\/a><a href=\"mailto:britta.nestler@h-ka.de\">britta.nestler@h-ka.de<\/a><\/p>\n<\/div><\/div>\n\n\n\n<div style=\"height:10px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"wp-block-media-text is-stacked-on-mobile\" style=\"grid-template-columns:15% auto\"><figure class=\"wp-block-media-text__media\"><img loading=\"lazy\" decoding=\"async\" width=\"161\" height=\"208\" src=\"https:\/\/www.for5134.science\/files\/2022\/02\/bild_daniel-schneider.jpg\" alt=\"Bild von Herrn Doctor Daniel Schneider als Mitglied im Leitungsteam des Teilprojektes 6\" class=\"wp-image-1280 size-full\" \/><\/figure><div class=\"wp-block-media-text__content\">\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/www.lpt.tf.fau.de\/lehrstuhl\/mitarbeiter\/lehrstuhlleitung\/\"><\/a><a href=\"https:\/\/www.h-ka.de\/en\/about-hka\/organization-people\/staff-search\/person\/daniel-schneider\">Dr.-Ing. Daniel Schneider<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\" style=\"font-size:16px\">Hochschule Karlsruhe University of Applied Sciences<br>Institute for Digital Materials Research (IDM)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"mailto:michael.schmidt@lpt.uni-erlangen.de\"><\/a><a href=\"mailto:koestler@i10.informatik.uni-erlangen.de\"><\/a><a href=\"mailto:lisa.scheunemann@ifam.rwth-aachen.de\"><\/a><a href=\"mailto:mlanser@math.uni-koeln.de\"><\/a><a href=\"mailto:daniel.schneider@h-ka.de\">daniel.schneider@h-ka.de<\/a><\/p>\n<\/div><\/div>\n\n\n\n<div style=\"height:50px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h4 class=\"wp-block-heading\">Sub-project researcher<\/h4>\n\n\n\n<div class=\"wp-block-media-text is-stacked-on-mobile\" style=\"grid-template-columns:15% auto\"><figure class=\"wp-block-media-text__media\"><img loading=\"lazy\" decoding=\"async\" width=\"130\" height=\"155\" src=\"https:\/\/www.for5134.science\/files\/2022\/03\/foto_muhammad_umar.jpg\" alt=\"Bild von dem Bearbeiter des Teilprojekts 6 Muhammad Umar\" class=\"wp-image-1896 size-full\" \/><\/figure><div class=\"wp-block-media-text__content\">\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/www.lpt.tf.fau.de\/lehrstuhl\/mitarbeiter\/lehrstuhlleitung\/\"><\/a><a href=\"https:\/\/www.h-ka.de\/en\/idm\/profile\">M.Sc. Muhammad Umar<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\" style=\"font-size:16px\">Hochschule Karlsruhe University of Applied Sciences<br>Institute for Digital Materials Research (IDM)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"mailto:michael.schmidt@lpt.uni-erlangen.de\"><\/a><a href=\"mailto:koestler@i10.informatik.uni-erlangen.de\"><\/a><a href=\"mailto:lisa.scheunemann@ifam.rwth-aachen.de\"><\/a><a href=\"mailto:mlanser@math.uni-koeln.de\"><\/a><a href=\"mailto:daniel.schneider@h-ka.de\"><\/a><a href=\"mailto:muhammad.umar@partner.kit.edu\">muhammad.umar@partner.kit.edu<\/a><\/p>\n<\/div><\/div>\n","protected":false},"excerpt":{"rendered":"<p>Motivation Solidification cracking during laser beam welding (LBW) is a complex, multiscale and multiphysical phenomenon that originates in the microstructure. Sub-project TP6 investigates the formation and propagation of solidification cracks&hellip;<!--&hellip;--> <a class=\"more-link fa fa-angle-double-right\" href=\"https:\/\/www.for5134.science\/en\/teilprojekte\/teilprojekt-tp6\/\" title=\"Read more about &quot;Sub-project 6 - Microstructure simulation of solidification in the weld seam&quot;\"><\/a><\/p>\n","protected":false},"author":3020,"featured_media":0,"parent":1336,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"page-templates\/full-width.php","meta":{"_rrze_cache":"enabled","_rrze_multilang_single_locale":"en_GB","_rrze_multilang_single_source":"https:\/\/www.for5134.science\/?page_id=81","footnotes":""},"page_category":[13],"page_tag":[],"class_list":["post-1398","page","type-page","status-publish","hentry","page_category-general","en-GB"],"_links":{"self":[{"href":"https:\/\/www.for5134.science\/wp-json\/wp\/v2\/pages\/1398","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.for5134.science\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.for5134.science\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.for5134.science\/wp-json\/wp\/v2\/users\/3020"}],"replies":[{"embeddable":true,"href":"https:\/\/www.for5134.science\/wp-json\/wp\/v2\/comments?post=1398"}],"version-history":[{"count":9,"href":"https:\/\/www.for5134.science\/wp-json\/wp\/v2\/pages\/1398\/revisions"}],"predecessor-version":[{"id":2868,"href":"https:\/\/www.for5134.science\/wp-json\/wp\/v2\/pages\/1398\/revisions\/2868"}],"up":[{"embeddable":true,"href":"https:\/\/www.for5134.science\/wp-json\/wp\/v2\/pages\/1336"}],"wp:attachment":[{"href":"https:\/\/www.for5134.science\/wp-json\/wp\/v2\/media?parent=1398"}],"wp:term":[{"taxonomy":"page_category","embeddable":true,"href":"https:\/\/www.for5134.science\/wp-json\/wp\/v2\/page_category?post=1398"},{"taxonomy":"page_tag","embeddable":true,"href":"https:\/\/www.for5134.science\/wp-json\/wp\/v2\/page_tag?post=1398"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}