Since the 1950‘s,when titanium came into use primarily in the aerospace sector due to its exceptional properties, the titanium industry has had several cycles of high and low demand with numerous new applications and industries over the years. Today, about 80% of titanium is used by the aerospace industry and 20% by non-aerospace industries such as metal finishing, chemical processing, consumer products and medical implants. The conversion of purified titanium sponge into commercially pure titanium or titanium alloys involves several processes with multiple processing steps and can nowadays be realized via two independent production routes.
In the VAR or sponge route, titanium sponge is mixed with various alloy additions in a dedicated weighing and blending unit, whereby the exact proportion of sponge to alloy material has to be carefully formulated and controlled. This mixture is then pressed into compacts and welded together in a vacuum plasma welding process forming a sponge electrode. This electrode is then subsequently remelted vertically into a water-cooled copper crucible under inert conditions in a Vacuum Arc Remelting process. This remelting process is normally carried out two to three times with intermediate machining to ensure uniform distribution of alloying elements to provide a technically acceptable ingot suitable for subsequent processing such as hot and cold deformation into mill products such as bar, billet, wire, tubing, plate and sheet by conventional forging and rolling processes.
Beside the classical VAR production line, the cold hearth remelting route is applied for direct melting, refining and casting of raw materials such as scrap, sponge and alloying elements into titanium ingots and slabs. Here the loose raw materials are continuously fed into a cold hearth remelting furnace where they are melted by high-energy electron beam guns. After casting and solidification, the produced ingots may optionally be vacuum arc remelted or conventionally processed by forging or rolling. A variant of the cold hearth technology is the Skull melting process where an electrode and other raw materials are melted in a in a water-cooled copper crucible under inert conditions in a vacuum atmosphere. The liquid metal solidifies forming a skull on the copper crucible surface which remains in the crucible. After the melting the crucible is tilted and the liquid melt is directly casted into moulds for ingots, slabs or investment cast parts.
With more than 15 years of experience as premium supplier serving the titanium industry, INTECO offers various technologies and equipment as well as the complete production know-how for different titanium production lines for individual demands of its customers. Starting from a feasibility and pre-investment study to overall definition of equipment and engineering as well as commissioning, INTECO can act as a technology partner and even support the customer in product certification such as needed for the aerospace industry.
Furthermore, INTECO has developed a sophisticated production management system (IMAS) covering the entire process route including pre-defined procedures and ultimately an operator independent and repeatable process, already complying with the requirements of industry 4.0.
USPs of INTECO Design
- Long term operational experience and know-how of full scale titanium production plants including certification for the aerospace industry
- Experience in the engineering and commissioning of entire titanium production shops from raw material to finished ingots
- Supply of newly developed titanium VAR (I-Ti VAR) based on well proven and in-house developed VAR technology
- Supply of Skull melting furnaces (I-Ti VA SM) based on a revolutionary new design concept
- Customized Process and Production Management System (IMAS) for titanium production lines
- Advanced process modelling as the key tool for a better understanding and process optimization
Available Equipment & Technology
- Sponge - VAR and cold hearth titanium production routes
- Entire production lines or single units
- Ti VAR plants from lab scale up to 17t ingot weight with different design concepts of VAR in terms of productivity
- VAR skull melting furnace with pouring weight from 250kg up to 1.700 kg for high recycling rates (>40%)
The Vacuum Arc Remelting of titanium is a core technology for producing commercially pure and alloyed titanium with high demand on purity and quality. The remelting of titanium in principle is very similar to the VAR remelting of steel and nickel based alloys but with different aspects dedicated to the process control and the plant design itself. Usually higher melt rates are applied for titanium resulting in increased melt power and cooling capacities. An arc centralization system is key to form a uniform and centralised melt pool during remelting. This is realised by an inductive coil wounded along the melt station which creates a tangential force of the magnetic field to centralize the electric arc underneath the electrode and provides also a melt bath movement. Further it calms down the liquid pool movement by selection of proper stirring interval time, resulting in a stabilized electric arc and correspondingly less Voltage fluctuation. Due to the high reactivity of titanium, the after cooling of the re-melted ingot must take place under vacuum or protective gas atmosphere which has a certain impact on the plant productivity. Vacuum tight lock valves above the melt station can be installed to seal the atmosphere during the after cooling period allowing the furnace head to continue the production at the second melt station. Certain measures for operator safety have to be taken such as restricted access to the plant area during the re-melting process and a concrete wall around the plant protecting the operators.
Based on INTECO´s long-lasting experience in the field of Vacuum Arc Remelting of steels and super-alloys, INTECO has developed a new and innovative furnace concept for titanium remelting which features all state-of the art characteristics. Furthermore, a comprehensive process simulation model has been exclusively developed with the Montanuniversity of Leoben to provide further insights into this complex remelting process allowing our customers to enhance their process know how and optimize their entire production.
Main design features
- Advanced arc centralization system for homogeneous distribution of the magnetic field from the bottom to the top for highest safety and improved metallurgical performance
- Optimized cool down period with advanced lock valve design
- Comprehensive process simulation model exclusively developed with the Montanuniversity of Leoben
- Holistic process and production management system (IMAS) for overall data management, data storage and definition of key performance parameters
The Vacuum Arc Skull Melting process was developed for the production of castings using a regular consumable electrode from VAR (e.g. from VAR) to melt scrap and other raw materials in a water-cooled copper crucible. The process takes place under vacuum atmosphere and the electric arc is ignited between the electrode and the water-cooled copper crucible. The liquid metal solidifies forming a skull on the copper surface which remains in the crucible after the pouring of the metal in the mould. Homogenization of the chemical composition as well as refining the melt from refractories and impurities is obtained by a long soaking time of the liquid metal and the heavier particles remaining in the skull. Renewed melting of the skull during the campaign will dissolve any impurities to a wide extent with the result of receiving impurity-free melts. The process can provide either ingots, slabs or investment cast parts (Single or Double Melt) which may optionally be vacuum arc re-melted or subsequently processed.
INTECO´s revolutionary and innovative Skull Melter design is the result of long lasting experience in the field of Vacuum arc re-melting and Vacuum casting. Two different casting techniques are combined in one plant by using either static casting to provide ingots, slabs or dynamic casting for investment cast parts. A very attractive highlight, from a technical and economical point of view, is the fact that recycling rates of up to 100% of titanium scrap can be achieved.
Main design features
- The possibility to use a double round cold skull crucible (oval shape) for increased metallurgical efficiency and cast weight flexibility > 1000 kg
- A drum feeder for use of additional feedstock / alloying feedstock to allow economical raw material use and adjustment of the chemical composition of the electrode. Recycling rates of titanium scrap up to 100% can be achieved.
- Two Titanium casting techniques are combined in one plant:
- Static casting for producing ingots, slabs or investment cast parts
- A rotational cast table with auto balancing system with high balancing accuracy for dynamic casting can be used for centrifugal casting technique to achieve advanced product complexity and properties
- Load cell system at crucible and casting chamber for accurate and precise pouring weight control
- Split melt - and casting chamber design allowing easy access for crucible and casting setup exchange as well as maintenance and cleaning
- Easy loading and unloading process of electrode
- Multicasts of one electrode for 5-6 casts possible
- Fully automated crucible tilting/pouring process and programmable pouring speed
- Holistic process and production management system (IMAS)