Liberty Speciality Steels accelerates production of ultra-clean speciality steels with new vacuum induction melting furnace Reprint from MPT International (2017), issue-no. 4, page 48 53.
LIBERTY SPECIALITY STEELS Liberty Speciality Steels, Stocksbridge, Sheffield, UK Contact: www.libertyspecialitysteels.com E-mail: contactus@specialityuk.com SMS group, Düsseldorf, Germany Contact: www.sms-group.com E-mail: thilo.sagermann@sms-group.com 2
Liberty Speciality Steels accelerates production of ultra-clean speciality steels with new vacuum induction melting furnace At its Stocksbridge, Sheffield site (South Yorkshire, UK), newly formed Liberty Speciality Steels is improving its specialist alloy manufacturing facilities by increasing production levels at the VIM X-eed vacuum induction melting furnace supplied by SMS Mevac. This new metallurgical facility produces high-purity steels and speciality alloys for extremely demanding applications like aerospace, motorsports and oil & gas. These facilities are coupled to a unique integrated mill, machined part and service centre offering, and are supplied globally as ingot, bar, cut piece or machined part. Liberty Speciality Steels the speciality steel business of Liberty Steel has been successfully producing alloy and stainless steel grades for over sixty years for use in demanding sectors such as aero space, oil & gas, industrial engineering and in the manufacture of bearings, bright bar, narrow strip and niche engineering applications for customers around the world. Their strength in speciality steels lies in the fully integrated production capability, which includes electric arc steelmaking, vacuum induction melting (VIM), mill processing capa- The ingots produced will be refined further by processing through a vacuum arc remelting unit before being rolled or forged into products (Picture by courtesy of Liberty Steel). 3
LIBERTY SPECIALITY STEELS bilities and dedicated service centres. Typical products include ingots, blooms, billets, bars, slabs and narrow strip; in cast, rolled, drawn, peeled, heat-treated or re-melted condition, in exactly the quantities required by customers. The production centres in Sheffield and the West Midlands area of the UK are backed by dedicated service centres in Bolton, UK, Nagpur, India and Suzhou and Xi an in China. The service centres enable Liberty Speciality Steels to service their customers supply chains with bespoke combinations of added-value processing and just-in-time delivery. More than 100 component and equipment manufacturers, end users, third parties and national bodies have validated the quality management systems. VIM plant enables Liberty Speciality Steels to deliver the highest purity steels Liberty Speciality Steels has gained an excellent reputation for supplying high-integrity steel to major commercial and military aerospace programmes around the world, using tailored supply chain solutions. Andrew Douglass, engineering director at Liberty Speciality Steels, underlines: We are a key supplier to some very significant aerospace players. He continues: It is definitely a growth sector in terms of aerospace production; Boeing forecasts a need for a record 41,000 new aeroplanes over the next twenty years. 38% of new planes will be for the Asian market, driven by China and India. Some of the most demanding products delivered as ingot, bar and cut pieces are used in the production of engine components, landing gear, controls, aerostructure, helicopter rotor components, etc. For the production of such materials Liberty Speciality Steels has been operating numerous remelting plants, i.e. two electro-slag remelting plants (ESR) and nine vacuum arc remelting (VAR) plants at the Stocksbridge site, with feedstock mainly provided by the nearby steelmaking operations. However, the business previously supplied small quantities of VIM-derived steel using ingots sourced from third parties. Because of the enormous potential of the growing market, in 2013 the company decided to invest in creating its own VIM base. In late 2013 the company announced it would build together with SMS group a vacuum induction melting (VIM) furnace at its Stocksbridge site to enable the steel producer to tap into new market opportunities and develop on its own innovative new products for the aerospace and oil & gas industries. A challenging project had been launched. The company decided for a brownfield project. The furnace location was the site of a former continuous billet casting plant, in order to take advantage of existing buildings, overhead cranes and plant services. The final layout integrated the main furnace components with the raw materials preparation area, the crucible relining and pre-heating area and the mould preparation and ingot stripping area. VIM: vacuum induction melting process The VIM facility produces ultra-clean ingots, i.e. remelt electrodes, that will be refined further by a remelting process, usually a vacuum arc remelting (VAR) unit before being rolled or forged and finally manufactured into products such as engine, transmission and structural components for the aerospace market. Tapping and all other process sequences are remote controlled and monitored from the control room. 4
The VIM production route involves vacuum melting high-purity steel and alloys in a crucible furnace, and then vacuum casting the purified liquid steel into ingot moulds all within a low pressure vacuum chamber (vacuum level approx. 0.05 mbar or even less). The VIM technique comprises consecutive process steps as follows: The upper furnace and lower crucible are sealed together, evacuated and charged with raw material. The raw material is melted by electrical induction heating. Induced current stirs the liquid metal; exposing it to the vacuum during hours of refining to remove gasses. Alloying elements can be added under vacuum. Moulds are prepared and set. The moulds travel on rail car into the casting chamber. Launder/tundish are prepared and set. Launder/tundish travel on rail to the casting chamber. Casting chamber is sealed and evacuated and connected to the melting chamber. After setting the exact composition of the alloys and the casting temperature, the liquid metal is tapped under vacuum. The furnace tilts forward to pour liquid metal via the launder/tundish into the mould during casting. After casting: the filled mould exits the casting chamber on rail car to the stripping area. After hours: the solidified ingots are stripped out and placed under insulated hoods to cool slowly. This prevents cracking of sensitive steel grades. As the entire melting and casting operation is conducted in an oxygen-free atmosphere, the resulting steel is very clean and has very low gas content. The technology enables the achievement of very tight analytical tolerances. Alloying additions, also carried out under vacuum, allow for precise control of the steel s chemical composition. Melting in an oxygen-free atmosphere prevents the formation of oxides and also the loss of elements with an affinity for oxygen. Unwanted accompanying elements which have a high vapour pressure can be removed. The ingots produced will be refined further by processing through a vacuum arc remelting (VAR) unit before being rolled, or forged into products such as engine, transmission and structural components for the aerospace market. Production of speciality alloys at the Stocksbridge works, using the new VIM X-eed unit supplied by SMS group. 5
LIBERTY SPECIALITY STEELS Launder/tundish prepared and set for tapping under vacuum. Technological concept and machine design The concept of the VIM unit is based on a three-chamber system, in which casting, melting and exchange chambers are arranged adjacent to each other. The independent design of the three chambers allows for individual evacuation of those. The heart of the VIM X-eed unit comprises an 8 t vacuum induction melting crucible and the associated vacuum pumping, material charging and process control equipment. All core components supplied by SMS Mevac have been designed to allow Liberty Speciality Steels to increase the melt size to 18 t at a later date. The mechanical vacuum pump system consists of three skids that can be connected in parallel or alternately at three exhaust points (melting chamber, casting chamber and exchange chamber/charger). To protect the vacuum pumps against dust and metal particles, SMS group has developed special dry-type filters for this application. Separate filter systems have been installed for each chamber. 6
Also ancillary equipment for crucible preheating and lining maintenance was included in the supply scope. The plant incorporates vacuum pouring equipment for both top poured and bottom poured ingots, in single or multiple ingot configurations. All process sequences are remote controlled and monitored from the control room. The main process parameters and status indications as well as all important system functions are displayed on the HMI monitor and are additionally recorded to permanent files for full quality assurance traceability within the Level 2 process control system. The condition of the heat and casting operations are visualized on separate video monitors using dedicated process monitoring cameras. Conclusion Liberty Speciality Steels takes pride in satisfying customer and OEM requirements from state-of-the-art specialist alloy manufacturing facilities which include vacuum induction melting (VIM) alongside vacuum arc remelting (VAR) and electro-slag remelting (ESR). These facilities are coupled to an integrated rolling mill and service centres, which allow the company to deliver its products around the world as ingot, bar, cut piece or machined part. Their highly qualified technical teams provide advice and help with day-today problem solving, and are available to assist with longer-term developments. Andrew Douglass, engineering director of Liberty Speciality Steels: We are delighted to have the VIM in operation and producing aerospace grades for sale and customer acceptance trials. Jochen Schlüter, managing director of SMS Mevac: We are very proud of having installed and successfully commissioned the new VIM X-eed facility in Stocksbridge in close collaboration with Liberty Speciality Steels. As partners of Liberty Speciality Steels, we will continue to render our extensive metallurgical expertise to support our customer in developing and producing innovative highend materials with the newly installed VIM X-eed unit and responding successfully to the increasing requirements of this extremely exacting market. Liberty Speciality Steels Liberty Speciality Steels is a division of Liberty Industries Group, part of the metals and industrials group Liberty House. It employs 1,700 people at its major steel melting and processing sites in Rotherham, Stocksbridge and Brinsworth, South Yorkshire, service centres in Bolton, Lancashire and Wednesbury, West Midlands and two distribution centres in China. The business produces a range of high-value steels made from recycled materials that are used in manufacturing components and finished goods for aerospace, automotive, oil & gas and industrial machinery sectors. Liberty House The Liberty House Group is an international industrials and metals business specializing in commodities, metals recycling and the manufacture of steel, aluminium and engineering products. It operates from four hubs in London, Dubai, Singapore and Hong Kong and has presence in more than 30 countries. Its current turnover is over US$ 6.8 billion per annum. Liberty, along with its sister energy company SIMEC, is part of the worldwide GFG Alliance. SIMEC SIMEC is a resources group spanning five continents and encompassing major operations across shipping, infrastructure, mining, energy and commodities. The business is part of the GFG Alliance and was established over 50 years ago by Mr Parduman K. Gupta, who remains chairman. Latest SIMEC turnover exceeded US$ 2.7 bn, with net assets valued at US$ 796 m. GFG Alliance The GFG Alliance is an association between PK Gupta and Sanjeev Gupta s business interests to forge a new agile, sustainable, non-cyclical, integrated, global business model. Its key focus is the creation of a resilient supply chain from liquid metal produced from recycled scrap and renewable energy to highly-engineered products, funded through a pioneering financial approach. The group encompasses: Liberty House Group an integrated international industrial and metals business; SIMEC Group an international resources and infrastructure group; Wyelands a banking and financial services arm; GFG Estates a division that manages the alliance s property holdings; and GFG Foundation which is focused on the retention and creation of engineering skills. 7
LIBERTY SPECIALITY STEELS Background information about VIM investment project MPT International talked about the background of the VIM investment with Andrew Douglass, Engineering director, and Stephen Carey, manager Technology & Development, both Liberty Speciality Steels, Stocksbridge, Sheffield, South Yorkshire (UK). The answers provide an insight into the company s strategy in the respective market. What is the total sum invested in the speciality steelmaking facilities at the Stocksbridgworks? Andrew Douglass: There was recently significant investment in the business here in Stocksbridge. We probably invested 20 30 million during a period of approximately five years in various finishing and heat treatment activities not all new facilities, but also refurbishing of existing plants. We upgraded the peelers, invested in the rolling mill. Here we built a central control pulpit to take all the operators away from the mill train. The new central pulpit has been interfaced with the old mill controls. Additionally, we bought two new VAR plants and the VIM plant. Andrew Douglass, Engineering director, says: Aerospace is definitely a growth sector. That was one of the key points when we designed the new VIM capacity. What was the basis for the decision in favour of the VIM and why are you focusing on this technology? Andrew Douglass: Certainly, the target is always around the high added value. We had growth plans around supplies to the aerospace industry which would involve additional vacuum capacity. That was one of the key points when we designed the new VIM capacity and went for the option of a bigger crucible. The move from the 8 t to an 18 t crucible is very much in line with the aerospace growth plans. Aerospace is definitely a growth sector. We can see the growth, so it is important for us to act, because we are a key supplier to some very significant aerospace players. Stephen Carey: In addition to routine commercial production, the VIM furnace gives us the opportunity to develop new products and alloys. We can rapidly scale up from labo- ratory melts to heats of 4 to 8 tonnes made on the new VIM furnace. These are then processed and evaluated through our downstream processes. How do you evaluate your footprint in the market for aerospace products? Andrew Douglass: The aerospace sector is very much an international market. The supply chain will go through some of the key aerospace players OEMs, who supply components to the aircraft companies. Our steel will be in the components, like engines or landing gears, that the OEMs supply to the aircraft companies. We are already part of the global supply chain where business is based on long-term supply contracts. We have established supply channels in various regions and countries to support that. 8
What is your growth plan in terms of sales? Andrew Douglass: We definitely have set ambitious targets for strategic 5-year and 10-year growth plans for our aerospace segment. A lot depends on customer approvals. We want to broaden our range of steels to sell more. That s one of the reasons for our investments in new technologies, but also for future capacity increases. There is a big pipeline of what we want to be able to offer in the future. Currently on the VIM we manufacture mainly 12 grades of alloy and stainless steels. We are increasing the value of what we are supplying, basically by adding higher alloys and more stainless grades to increase our portfolio. It is important to note that we are already in the market with various of these grades. Now we are reaching out for additional customer approvals for grades that we are already producing. Also, with our new VIM plant we can add new grades that we never made before, which include certain alloyed steels and also super alloys. The rational for our investment in the VIM was that previously we had been buying VIM ingots from 3rd party suppliers to be remelted in our VAR shop. That gave us a foot in the market. Some of our key customers have expected us to seriously enter into VIM products supply by setting up our own VIM production facility. That was part of our growth plan. Now, as we have our own VIM manufacturing base, these customers consider us to be a more credible supplier of VIM products. Since application of VIM products is increasing, our market share for such product is increasing, too. Had we not invested, we would have less opportunities with these key customers. Now, as we invested, we are on a more level playing field with some of our competitors. It will ensure our competitiveness over a long term and with a wider product range. Stephen Carey, manager Technology and Development: The VIM furnace gives us the opportunity to develop new products and alloys. Do you produce materials with customized characteristics? Stephen Carey: Most of our products have to meet standard specifications like AMS or European standards, or multiple classifications. These include products for very demanding applications. The steels have to meet challenging combinations of metallurgical properties, for use in helicopter transmissions, formula-1 gears, etc. Most of these products require production via the VIM-VAR route, to achieve the required levels of cleanliness, analysis control and mechanical properties. We already have a number of existing approvals that we want to transfer to our new in-house production route. As we now have the capability to produce larger quantities by the VIMVAR route, we can offer many more products for new applications in aerospace and other sectors. 9
LIBERTY SPECIALITY STEELS Why did you decide for VIM technology from SMS Mevac? Stephen Carey: SMS group is highly regarded in terms of their engineering. We have had close relationships with the SMS group as our plant supplier in other parts of the company. As this was to be the first VIM plant built by SMS Mevac, there was a very good opportunity for us to work closely together with the engineers from SMS Mevac. This was a development project, where we could bring the operator s perspective to the design. For us it was a brownfield project. We had to design the facilities to fit into our existing site footprint. However, we had the opportunity to start from a blank sheet and SMS Mevac were able to accommodate our requirements in their layout design. Finally, since this is a reference plant, it was designed to a very high specification, in terms of vacuum performance, productivity and metallurgical capability. Andrew Douglass: We are a highly credible supplier of VIM steels to the aerospace industry. We are open for business. We develop steels. All our customers know that there are two main (plant) suppliers to the VIM industry, and we can underline that we opted for SMS Mevac because of the credibility and because we have got a really good plant. We both have a common interest, namely to make this project a success. Do you intend to continue investing in VIM-VAR plants? Andrew Douglass: Yes, absolutely. As explained before, the general backlog of orders for new aircrafts and the prospects of emerging nations like China and particularly India is the base for our growth plan. It is an area where we see positive market indicators. Our VIM facility is now being operated with a 8 t crucible, but we intend to increase production using the originally designed 18 t capacity. This new facility will enhance our portfolio and increase our production of the respective products. As all VIM production will go through the VAR and our VAR capacity is full we ll have to think about additional VAR plants if we increase our VIM production. Investment in additional plants is the logical answer. This way we can increase the size of the aerospace order book, which is going to put some strain on other areas of our organisation. In parallel we have started to implement our plans to automate a part of our testing regime for the aerospace products, which because of their very nature are highly test intensive. Commissioning of some of the automated test preparation equipment is already underway. Very soon, we will go ahead with an investment in automated testing facilities, which will also further enhance our on-time delivery performance. Yes, absolutely, we will continue investing in the VIM-VAR process route. It serves a growing market with good returns. It is one that we believe will acknowledge our expertise as product and service supplier and strongly underpin our commercial growth. Thank you very much for the interview. 10
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