Liquid Metal Processing & Casting Conference (LMPC 2022): Defects During Processing II
Program Organizers: Matthew Krane, Purdue University; Mark Ward, University of Birmingham; Abdellah Kharicha, Montauniversität
Wednesday 8:00 AM
September 21, 2022
Room: Grand Ballroom
Location: Bellevue Hotel
Session Chair: Ashish Patel, Timet
8:00 AM Introductory Comments
Dissolution of Al2O3, MgO·Al2O3 and SiO2 in Alkali Oxide Containing Secondary Metallurgical Slags: Nikolaus Preisser1; Julian Cejka1; Shashank Babu1; Gerald Klösch2; Susanne Michelic1; 1Christian Doppler Laboratory for Inclusion Metallurgy in Advanced Steelmaking; 2voestalpine Stahl Donawitz GmbH
The control of non-metallic inclusions is inevitable for the quality of cleanness sensitive steels. As alkali oxides have already been used in mould fluxes to achieve lower melting temperatures, it is suggested that there could be a positive effect on the inclusion removal in secondary metallurgical slags. In this work, the dissolution of synthetic particles in multiple alkali oxide containing slags is studied on a laboratory scale by means of High-Temperature Laser Scanning Confocal Microscopy. This method enables the in-situ observation of inclusion behaviour at steelmaking temperatures. Thermodynamic calculations using FactSage are additionally applied. In the experiments, Al2O3, MgO∙Al2O3 and SiO2 particles are in interaction with slags containing different amounts of Li2O, Na2O and K2O. Significant differences in dissolution time for the specific particle types are observed. Moreover, the dissolution mechanisms are investigated. Special focus is put on the influence of slag viscosity on the dissolution behaviour.
Characterization of the Inclusion-induced Surface Defects in Thin-gauge 1xxx, 3xxx and 5xxx Series Al-based Products: Pascal Gauthier1; Mousa Javidani2; Tao Wang1; 1Rio Tinto; 2University of Quebec
Thin-gauge aluminum alloy products for automotive and packaging applications are highly susceptible to surface pin holes/tearing defect. This type of issue is often related to the casting process defects (e.g., inclusions, oxides, etc.) and/or downstream rolling defects (e.g., roughness, mechanical wear, and debris in the rolling mill surface).This research aims to study the formation mechanism of inclusion-based surface defects in the thin-gauge Al alloy (e.g., 1xxx, 3xxx and 5xxx) products. It is found that these defects are formed due to the premature degradation of silicate-based insulation refractories. In addition, the improper use of the alumina-based refractories can create inconsistency during service, which ultimately results in the similar inclusion-induced pinhole issue in the sheet products. In this study, the optical microscopy and SEM were used to identify the inclusions and their origins from the upstream refractories used in the casthouse.
Kinetics of Oxygen Removal by Carbothermic Reduction from Steel Melts Under Vacuum Pressures: Andrew (Drew) Huck1; Bryan Webler1; Stephano Piva1; 1Carnegie Mellon University
Oxide inclusions are often after vacuum processing, even in double vacuum process pathways such as vacuum induction melting (VIM) to vacuum arc remelting (VAR). This result is thermodynamically inconsistent, as these features should not be stable at the typical vacuum pressures utilized neat the melt surface. This suggests that there are some significant kinetic limits to oxygen and inclusion removal from the melt. This work will outline some of the relevant kinetics of various removal steps and with various assumptions, outline the ranges of impact on the speed of oxygen removal from the melt. Some specific topics that will be covered are nucleation of carbon monoxide bubbles, overall mass transfer of dissolved species and inclusions, the effects of various deoxidants, and dissolution or direct removal of inclusions from the melt.
DANIELI Special Metallurgy, Introduction of a Key Player's New Product Line: Matthias Knabl1; Harald Graf1; Grygorii Sergiienko1; Rolando Paolone2; Roberto Sorci3; 1Danieli Engineering and Services GmbH; 2Danieli & C. Officine Meccaniche SpA; 3RINA Consulting - CSM SpA
DANIELI is worldwide known as one of the big full liners in the steel industry plant and technology supply. The new product line Special Metallurgy was founded to serve especially the highest quality sector using VIM, VAR and ESR with new ideas and plant concepts. Numerous renown experts – internal and external – are part of this new team with one office in Leoben, Austria as a cornerstone and well established DANIELI institutions worldwide as others. This paper introduces new ideas, plant concepts and features on the field of special metallurgy and describes first projects.
Enhanced Material Properties in Advanced Air Casting Applications by Means of Vacuum Cap (VCAP) Furnace Process
: Eike Schmilinsky1; Inaki Vicario; Martin Myška2; Roman Ritzenhoff; Aaron Teske3; 1Consarc - An Inductotherm Group Company; 2Brno University of Technology; 3Consarc Corporation
Air melting processes can suffer from limited control of alloy cleanliness composition. Oxygen and nitrogen levels vary from heat to heat, and given deoxidation with aluminum can cause non-metallic inclusions, the current practice is to add additional virgin material. Similarly, low vapor pressure contaminants like Pb, Bi, Zn, etc. are reduced via dilution. Carbon reduction is also a metallurgical challenge in air melting. VCAP furnaces are a hybrid of air induction and vacuum refining capability. The VCAP charge is melted in air. Once molten, a vacuum cap is applied to produce a significant degassing effect providing reduced casting defects, removal of trace elements, and promoting decarburization. Our research and production units results show improved mechanical properties and better micro-cleanliness. We present the main features of the VCAP technology as a recommended technique to obtain enhanced material properties and a more reliable air casting process.
10:10 AM Break
Investment Casting with Unique Levitation Melting Technology - FastCast: Sergejs Spitans1; Christian Bauer1; Henrik Franz1; 1ALD Vacuum Technologies GmbH
Based on numerical modelling a prototype FastCast furnace that utilizes novel method for the large-scale levitation melting (LM) and high-yield casting of metals has been designed and built at ALD. The demonstrator is intended for 10 consecutive single-shot castings. The melting starts as the lower end of the vertically oriented Ti-alloy electrode is immersed in the region of two-frequency horizontal and orthogonal electromagnetic (EM) fields. EM fields rapidly melt up to 500 g of material from the tip of the electrode and simultaneously confine the liquid metal in a levitation condition. The electrode is moved up and detached levitated melt can be superheated. After that the melt is released and it falls down under gravity in the awaiting preheated mould. Instantly the mould is accelerated vertically down to catch the melt without splashing and ensure the smooth filling. Experimental results of successful levitation melting and casting campaigns will be presented.
Extension of Investment Casting Process Simulation by Electromagnetic Modelling of the Pre-process Step of Billet Induction Melting: Victoria Thomas1; Ole Koeser2; Steven Leyland3; Stephen Brown1; Nicholas Lavery1; 1Swansea University; 2Calcom ESI SA; 3Uni-Pol Group
An innovative method of modelling vacuum induction melting (VIM) is developed for industrial casting software, with applications in the investment casting industry. An induction coil is used to melt a nickel-based superalloy in a ceramic crucible. Once fully molten, the alloy pours into an investment casting mould which is attached underneath the crucible. The approach involves performing induction heating simulations to determine the temperature profile of the billet, at the point which it becomes fully molten. This is then applied as the initial condition for a mould filling and solidification simulation. Temperature data for the alloy is compared to experimental results obtained from in-situ industrial experiments using a bespoke VIM chamber with additional viewing ports. The benefits of applying this methodology for simulation modelling are explored. This includes improved defect occurrence prediction for finished castings, by capturing defects which were not predicted by a standard modelling process.
Final Chemical Composition Variations Due to the Effect of Different Power Input Rates During VIM Melting for Superalloy Investment Castings: Oscar Caballero1; Jesus Mariano Arnesto1; Daniel Bernal2; Pablo Garcia2; Xabier Chamorro2; Iñaki Hurtado2; Xabier Esquisabel2; Iñaki Madariaga3; 1ITP Aero Castings; 2Mondragon GEP; 3ITP Aero
The presenters have worked together in a R&D Project for relating power input rates applied in the investment casting VIM furnace with final cast parts NDT indications. The performed work was divided in three parts: Firstly, MGEP developed a melting process model. Temperature distributions are simulated as a function of power rate inputs. Secondly these temperature differences effects are assessed. They cause different chemical reactions in the alloy and with the rest of surrounding elements (residual gases or refractories). The different times/temperatures lead so to variations on chemical compositions. Finally, those variations in chemical compositions promote the generation of different kinds and amounts of defects on the final investment casting products.The current presentation focuses on the second part and relates (at least qualitatively) the observed chemical compositions changes when different input rates used during melting and with the defects on the so produced superalloy investment castings.