The presentation will highlight the recent developments in the world of remelted steels, titanium and powder metallurgical as well as will give an overview about end-user demand and structures of these special materials and also summarize the actual status of installations on a global scale. The speech will also focus on the production and especially its associated production technologies and...
Evolution of Si concentration in 316 stainless steel electrodes was observed during a melting campaign consisting of recycling electroslag remelted (ESR) ingots to make new electrodes using vacuum induction melting (VIM). This campaign consisted of iterations of VIM + ESR operations to optimize melting parameters. The effect of Si content on the melt parameters and ingot quality was further...
coming soon...
ABSTRACT
Mathematical modelling studies of the remelt processes afford valuable insights into the solidification processes, but they generally present an instantaneous snapshot of conditions in the liquid pool rather than a global view of the entire process. This paper describes the development of simulators for the ESR (round and slab) and VAR remelt processes in different production...
ESR ingots of varying sizes -- 4”, 6” and 8” diameter laboratory scale ingots and commercial scale 20” diameter and 10”x42” slab ingots were produced using stabilized processes. Process control steps needed to stabilize the ESR process used to produce the laboratory 6” and 8” diameter ingots will be discussed, with attention to how the process was modified based on outcomes of employed trials....
It is generally believed that electroslag remelting can effectively reduce the number of large-size nonmetallic inclusions in steel and improve solidification structure, thus electroslag remelting (ESR) has become the main method to produce high quality die steel. However, large-size inclusions (D and Ds type) have been aperiodically detected in the production-scale ESR die steels. The...
This paper presents the results of laboratory and industrial scale investigations into the internal processes of electroslag remelting (ESR) facilitated by an external array of magnetic field sensors. Electroslag remelting is a crucial metallurgical process employed for the refinement and production of high-quality metal ingots, particularly in the context of alloy manufacturing. Real-time...
This paper investigates the effect of different electroslag remelting processes on the solidification quality and corrosion resistance of S136 steel. The results show that the double circuits process can reduce the mass fraction of oxygen in the ingot and effectively improve the cleanliness of the ingot. Analyzing the solidification quality of ingots, it can be seen that the secondary dendrite...
A martensitic stainless tool steel was remelted by a Pressure Electroslag Remelting (PESR) process with deliberate cancellation of the remelting just before normal hot-topping operation. Enabling evaluation of the ingots melt pool profile, dendrite angle and spacing, and macrosegregation during normal remelting conditions. A longitudinal cross section (500x500 mm) from the top of the 500 mm...
Non-metallic inclusions (NMI) are an essential quality criterion for electro-slag remelted products. Besides standardized testing methods such as ASTM E45, SEM-EDX-based methods have gained widespread application, as they provide not only information on shapes, sizes and numbers of NMI, but also about their chemical composition. Therefore, they are a useful tool not only for quality control...
Ni-based superalloy are sensitive to segregation during solidification and special care must be taken to control final chemistry on billet. Especially, some alloys are very sensitive to the formation of freckle type defect. Thus, the prediction of the evolution of the liquid phase composition and density during solidification is necessary to develop the corresponding melting conditions....
Modelling the Vacuum-Arc-Remelting (VAR) of NiFe-Based alloys like alloy 718 is motivated by its potential role in the further development of the process. It offers insight in the complex interaction of fluid mechanics and thermodynamics in a process which is experimentally hard to monitor. Nonetheless the numerical description itself requires a full definition of relevant boundary conditions...
The implementation of the feeding is a crucial and effective technique for preventing the accumulation of inclusions and the formation of shrinkage cavity at the top of electroslag ingot. In this study, a whole process model of electromagnetic-magnetic-flow-thermal inclusion removal with the full coupling of electroslag remelting of H13 die steel was established. The accuracy of the model was...
An industrial scale experiment on the impacts of process variations on ingot quality of IN718 was carried out by monitoring the associated magnetic fields by VARmetric. The test performed monitored operational variations during the processing of the ingot when different arc gaps were maintained. A short, medium, long, and extra-long arc gap were chosen during the melt, the system was allowed...
Computational modeling of the Vacuum Arc Remelting (VAR) Process has been developed to provide a deeper physical and metallurgical understanding and assist in the reliable and efficient manufacture of defect-free ingots. While 3D VAR models with transient (time varying) arc behavior have been developed, 2D axisymmetric models with steady-state arc boundary conditions remain the primary tool in...
External transverse magnetic fields were applied during the vacuum arc remelting of 900 mm and 1000 mm Ti6Al4V ingots in order to control the arc dynamics. The overall goal of the industrial experiments were to provide a known arc distribution throughout the melt, including startup and hot topping, that optimizes solidification. Magnetic field sensors (VARmetric) were deployed to continuously...
A twin-roll cast material of Mg-9.0 mass%Al-0.72 mass%Zn-1.85 mass% Sn-0.21 mass%Mn (AZT912) with 2.4 mm thick and 100 mm width that was given pre-strain after solution heat treatment was tested by V-bending at room temperature.
The purpose of this study is to fabricate a thin sheet plate for the practical use of plastic forming in room temperature by using twin-roll cast Mg-9mass%Al-1...
In order to advance the development of innovative lightweight materials, it has been clarified the effects of heat treatment of magnesium alloys and silane coupling conditions on the bonding strength of the laminated Mg alloy/polymer material. Effects of silane coupling condition on bonding have been mainly discussed on laminated Mg alloy/polymer material.
It has been considered that the...
High performance alloys for Aerospace applications are cast in cylindrical copper crucibles. Maintaining the appropriate crucible taper and diameter is critical to a quality casting. The use of micrometers, feeler rods, visual inspection is popular for a quick assessment of crucible diameter and condition. In this work, a sensor is used to measure the crucible diameter, and video camera to...
The Vacuum Arc Remelting (VAR) process is employed in the production of Nickel-based alloys, including Alloy 718. However, challenges arise during the process due to solidification shrinkage, leading to the loss of contact between the ingot and the mold. This phenomenon diminishes the cooling efficiency of the system, resulting in a deeper melt pool and a decline in ingot quality as heat...
This paper conducts an analysis of the Vacuum Arc Remelting (VAR) process to manufacture steel, examining the interplay of factors such as side-arcing, arc distribution types, thermal radiation, magnetohydrodynamics (MHD), and ingot solidification. The proposed numerical model explores how these factors influence the molten metal pool profile, which is a critical aspect in ensuring the...
Vacuum arc remelting is widely recognized for its ability to produce high quality ingots for demanding applications. Since its introduction in the 1940s, great efforts have been undertaken to increase productivity, reliability and furnace safety by different iterations of furnace design accompanied by improvements in process data acquisition and interpretation to allow remelting behavior...
In the field of metallurgy, the optimization of the process has driven the integration of advanced numerical simulations to enhance the efficiency and reliability of industrial systems. This article focuses on the application of 3D numerical simulations to investigate the cooling system of a Vacuum Arc Remelting (VAR) furnace, an essential component in the production of high-quality alloys....
In 2022 and 2023, for the needs of company Feinguss Blank GmbH, DANIELI developed and built an innovative middle size VIM for the remelting of Ni- and Co-based superalloy scrap from investment casting into barsticks. Several technical challenges, particularly unfavorable scrap geometry, its back-charging etc. were solved. The furnace realizes both, direct pouring and pouring via tundish. Some...
This paper describes the development of a new type of Vacuum Arc Cold Hearth Skull Melting & Casting (VA CH SM) process and design concept which is based on the well-established Skull Melting & Casting process and industrial proven cold hearth technologies.
Driven by the current challenges on the titanium and raw materials market and in line with the global target of reducing carbon...
Titanium alloys are increasingly used in aeronautical applications, a sector that requires highly controlled materials. In particular, inclusion cleanliness is a necessary and mandatory condition for safe use of aeronautical components. During the production and processing of titanium alloys, inclusions could appear, with two distinguishable types: low density inclusions (LDI) and high-density...
The iron and steel industry is undergoing significant changes due to global efforts to combat climate change, like the Paris Agreement and the European Green Deal. These initiatives aim for the European Union to become carbon neutral by 2050 and significantly reduce greenhouse gas emissions by 2030. This is a big challenge for the industry, which produced 1.95 billion tons of crude steel in...
The Electric Arc Furnace (EAF) has become increasingly popular in the industrial metal production sector in recent decades, undergoing substantial growth. At present, over 30% of steel production relies on electric arc furnace technology. In light of the harsh conditions surrounding the electric arc, numerical modeling emerges as a valuable tool for examining its behavior throughout the...
As part of its commitment to environmental sustainability, the steel industry constantly seeks to enhance operational efficiency. A significant area of focus is the optimization of temperature control in meltshops, a process traditionally constrained by the limitations inherent in Level 2 systems. These systems, characterized by static optimization and compartmentalized operations, lack a...
The understanding and controlling of the primary solidification, particularly the formation of first grains, is of significant relevance. Generally, high-Mn steels exhibit a coarse-grained microstructure in the millimeter range and are known for their high strain hardening ability and thus, excellent cyclic deformation resistance. In order to further improve the cyclic mechanical properties,...
The concept of the mechanical stirring technology was developed by INTECO to investigate the influence of mechanical rotation conditions on the solidification structure and to evaluate whether a similar or greater positive effect can be achieved than with electromagnetic stirring (EMS). The great advantage of the mechanical stirring effect compared to the EMS system is that forced convection...
Continuous casting (CC) became the world-leading technology for steel production. The thin slab casting (TSC) features a slab shape close to the final products, which are cast at high speeds and rapid solidification rates. The quality of the thin slabs is defined by the turbulent flow pattern and superheat distribution influencing the growing solid shell. To control the fresh melt feeding...
Electromagnetic stirring (EMS) has been recognized as a mature technique in steel industry to control the as-cast structure of steel continuous casting, and computational magnetohydrodynamic (MHD) methods have been applied to study the EMS efficiency. Most MHD methods de-coupled the calculations of electromagnetic and flow fields or simplifications were made for the flow-electromagnetic...
A common problem in continuous casting of steel is clogging of submerged entry nozzle (SEN) that occurs due to the continuous build-up of solid material. Clogging reduces productivity of the process and quality of the final product. The authors have developed a volume average model for particulate clogging of the nozzle. In this model, clog is treated as a developing porous medium due to the...
A two-phase columnar solidification model considering fluid flow, heat, and solute transport is applied to simulate the solidification in a 3D rotating geometry using the finite volume method. Molten steel alloy is confined within a rectangular cavity, initially at a temperature above the liquidus, with distinct hot and cold surfaces at the top and bottom, respectively. A slow cooling rate of...
Abstract
The performance of data models and their associated machine-learning routines for simulations of multi-physical continuous casting processes are scrutinised in this research work. Data science techniques have already started to have a significant impact on optimisation and controlling of manufacturing processes by providing fast and real-time predictive-corrective tools. These...
Abstract
Simulating the inclusion removal process in a tundish requires the consideration of large range of time and length scales.[1.] Because of both the steel and argon inlet, small timesteps as well as a fine mesh are required due to turbulence. On the other hand, the cleaning process itself takes comparatively long times to reach a steady state and consequently large computational...
The formation of freeze lining (FL), a protective layer of solidified slag, holds significant economic value in industrial processes by safeguarding furnace reactors and refractories from corrosive molten slag and providing a thermal barrier that minimizes energy consumption. To deepen our comprehension of FL formation, a collaborative research project has been undertaken, bringing together...
The AOD (Argon Oxygen Decarburization) converter process is a dominant process step in the production of high-quality stainless steel, with gas injection playing a critical role in influencing process efficiency and product quality. This paper focuses on developing a mathematical model for gas injection in the AOD converter process, utilizing advanced Computational Fluid Dynamics (CFD)...
Energy expenditures for slag and metal melting primarily drive production expenses of electro-metallurgical smelting processes. In Electroslag remelting (ESR), the thermal energy is directly generated by resistance heating of the slag system. Therefore, exact knowledge of the electrical conductivity of the molten slag is vital for regulating the process temperature and energy costs during...
Advanced techniques for liquid metal processing and casting, such as monocrystalline casting, atomization for powder metallurgy, metallic additive manufacturing, welding or ingots refining processes, are complex to master. Developing and controlling industrial equipment is costly and so manufacturers are promoting digital design methods. But numerical models rely on accurate knowledge of...
Non-metallic inclusion have a strong impact on the final product quality in
steel production. Thus, inclusion removal from the melt is an important aspect
of achieving the intended steel properties. In continuous casters the tundish
can be utilized to enhance inclusion removal. One method to promote inclusion
removal within the tundish is the installation of an argon bubble...
Stainless steel is widely used in extreme environments due to its high corrosion resistance. In particular, materials for applications requiring high reliability such as medical devices and etching equipment are produced with EBM, ESR, or VAR to reduce inclusions. These processes do not use refractory materials and thus provide better cleanliness than conventional melting methods. Especially...
Electroslag remelting (ESR) and vacuum arc remelting (VAR) are widely employed techniques for producing defect-free ingots in ferroalloys, nonferrous metals, and superalloys. These technologies find applications in sectors like military, aerospace, and aeronautics, where high performance is of paramount importance. Given the critical nature of these applications, a comprehensive understanding...
Compared with liquid iron, pure liquid nickel has a relatively limited solubility for nitrogen. Studies that have measured solubility have found values ranging from literally zero in one case to 35 ppm at 1600 C at the high end. Studies that examined the effect of temperature found the reaction to be endothermic with solubility increasing with temperature. Solubility predictions based on...
The High-Temperature Confocal Scanning Laser Microscope (HT-CSLM) is a powerful tool for in-situ investigations of surface phenomena and has proven its suitability for metallurgical processes. It is widely used to observe phase transformations, melting behavior, agglomeration of non-metallic inclusions (NMIs), or dissolution of particles in slags. However, these processes have been studied as...
Erosion in refractories plays a dominant role in the wear of these materials which is of significant relevance to the metallurgical industry. Not only is the lifespan of these materials affected by erosion but also steel quality can be reduced through the introduction of exogenous inclusions. In their application these materials are exposed to aggressive melts and intense flow conditions. The...
This study highlights a dissolution experiment conducted by high-temperature confocal laser scanning microscopy (HT-CLSM). Besides providing essential information on particle dissolution inside slag, this experiment constitutes a slag-argon multiphase environment and reveals particle behavior in the vicinity of the interface. It is observed that after the slag melts, the particle initially...
In Al casting alloys, iron (Fe) is known as an impurity that forms during solidification as a β-Al4.5FeSi phase, a brittle, plate-like structural component. This β-phase leads to negative influences on the mechanical and casting properties. Its presence favors stress concentrations at the plate edges. It can also promote shrinkage porosity and a reduction in feeding performance.
Fe is...
Continuous casting of steel is widely used to manufacture semi-finished long or flat products. Various stresses are present during slab casting: the stress caused by the friction between the mould wall and the solidified shell, thermal stresses acting on the strand surface, and the stresses due to the bending and straightening operations. During casting, the combination of the temperature and...
Laser ultrasound, a non-contact technique utilizing lasers for both excitation and detection of ultrasonic waves, offers an approach to assess structural and elastic properties in hot steel. This method employs an excitation laser emitting 7ns pulses at typically 10 to 100Hz repetition rate to generate ultrasonic waves through thermoelastic expansion and ablation. Detection is achieved via an...
The comprehensive metallographic analysis and statistical big-data analysis of blowhole appearance in heavy plate manufacturing gave no exact cause of defect formation but indicated differences in the chemical composition of defective and clean heavy plates and, above all, high content of residual elements. The rare BHs were found in the largest width ingot and on thinner plates that can be...
Feeding steel strip into molten steel in the mold is an effective technique for refining the solidification structure of steel (especially high-alloy steel) during the continuous casting process. This study experimentally investigated the effects of feeding strip on the solidification structure of super austenitic stainless steel S32654 and clarified the relative mechanism by combining...
For low carbon content personalized steel grades, the corresponding relationship between the banded microstructure at the typical position of 1/4 width of hot rolled steel coil and the W shape of the solidification end point of the cast slab was revealed. The influence of hereditary laws such as casting solidification structure and element distribution on banded microstructure was clarified. ...
Large inclusions (size ≥ 100μm) deteriorated the cleanliness of AISI 431 stainless steel ingots fabricated by a Chinese steel mill, resulting in the formation of defects that can be visually observed on the surface of the oil pump. Here, we revealed the Al contents and inclusion evolution route in the process of “AOD refining - LF refining - Casting - Rolling” by analyzing samples obtained...
