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N E W S L E T T w NEWSLETTER INTERNATIONAL TUNGSTEN INDUSTRY ASSOCIATION Rue Père Eudore Devroye 245, 1150 Brussels, Belgium Tel: +32 2 770 8878 Fax: + 32 2 770 8898 E-mail: [email protected] Web: www.itia.info 21st Annual New President and General Meeting, Xiamen, Vice-President of 22-26 September 2008 ITIA Xiamen Tungsten Company Ltd, Welcoming 280 delegates - a record since the first Elected at the AGM, Jesper Gullberg, Lead Buyer Raw Materials, Sandvik Tooling, succeeded Burghard which hosted this conference in Tungsten Symposium in Stockholm in 1979 - and noting that Xiamen meant “a gate of China”, Burghard Zeiler as President of the Association for the next two the (highly recommended) Sheraton Zeiler began his opening address by warmly expressing years and Stephen Leahy, Chairman and CEO of Hotel, was founded in 1997 the thanks of all present to Mr Liu Tonggao and Mr North American Tungsten Corp, became Vice-President. following the reorganisation Zhuang Zhigang, Chairman and President respectively of Xiamen Tungsten Company, for their generous of the former Xiamen Tungsten hospitality in hosting the meeting and for inviting Elections to the Products Plant. delegates to visit the Xinghuokeng Tungsten Mine; and to Mr Chen Qifang, Chairmen of Chaozhou Executive Committee Xianglu Tungsten, for arranging a tour of the � Robert Bunting, CEO, Beralt Tin and Wolfram company’s plant at Chaozhou. (Portugal) SA, Zeiler, who was presiding over his last meeting � Thomas Eizenhöfer, General Manager of after serving three years during an Business Unit, HC Starck GmbH, exceptionally busy and progressive time in ITIA’s � Wang Lixin, President, China Minmetals development, reported that ITIA and IMOA were Non-Ferrous Metals Co Ltd setting up separate Secretariats in 2009. He noted that the break with IMOA was long overdue as the work programmes of the two REACH and HSE, the education of this and future trade associations, whose joint membership generations about tungsten must, in his view, be a totalled 132 companies and whose budgets had crucial part of ITIA’s endeavours. XTC Chairman, Liu Tonggao (centre) and President, Zhuang Zhigang each multiplied fourteen-fold, could not be run (right), with the ITIA Secretary-General with the same staff of two persons despite the use Articles in the Newsletters which taught even those Our happy faces reflected the mood at that time ….. before doom and gloom descended. of external consultants. It had been an excellent already in the industry about tungsten, let alone those with enquiring minds; the development of the website; Below: Chen Qifeng, Chairman of Chaozhou Xianglu (right) with relationship which would not end totally as Thomas Eizenhöfer, General Manager (Business Unit) of HC Starck GmbH IMOA would let office space to ITIA in the same and updating of the brochure “Tungsten” were key (left) and Shin Un-Jic, Industrial Products Director, TaeguTec Ltd (centre) building in London. functions of this exercise, useful to all ages and experts and non-experts alike. Reverting to ITIA’s work programme, Zeiler Zeiler concluded by thanking his colleagues on the believed that ITIA could be proud of the Executive Committee for their devotion to ITIA’s initiative it had taken to set up the Tungsten activities; to the HSE Committee for managing an Consortium and the industry had been very onerous work programme so efficiently; to the fortunate that five companies had been prepared Technical Consultancy for their stimulating to join together to underwrite the Consortium, contributions; and to all members for their support as enabling it to get on with its work irrespective of evidenced by the presence of representatives from 51 out subsequent membership. But, important as were of 61 member companies. DECEMBER 2008 Continuing the series of informative articles began in 2003 about tungsten applications, its geology and mineralogy etc, the ITIA’s Technical Consultancy has written the following article about the use of Tungsten in Steel. TUNGSTEN IN STEEL Wolf-Dieter Schubert, Erik Lassner and Herbert Danninger Institute of Chemical Technologies and Analytics – Vienna University of Technology 1. INTRODUCTION Tungsten first found its unique place in technical applications in the The addition of tungsten to structural steels has decreased since 1940 mid-19th century, mainly in steel production, and until the first because alloying with Mo and Cr as well as with V and Ni yielded better quarter of the 20th century, its importance in this field steadily increased, performance at lower cost. Important applications of those steel types with the steel industry then the largest tungsten consumer. Tungsten have been outlet valves in combustion engines, crankshafts, rifle barrels was among the very first alloying elements systematically studied and etc. used to improve steel properties, for example hardness, cutting efficiency and cutting speeds of tool steels. Different tungsten containing steels From 1927, when cemented carbides (hardmetals) were developed, the were developed in Austria, Germany, France and England followed by proportion of total tungsten consumption used in steelmaking declined high speed steels in the USA. Pioneers in the field of tungsten constantly to a current figure of about 20%, but nevertheless this means applications in steelmaking were Franz Köller, Franz Mayr, Robert that steel is today still the second biggest consumer after hardmetals. Mushet, Sir Robert Hadfield, as well as Frederick Winslow Taylor and This percentage is the average for entire global demand. Regarding Mansel White. Further historical details can be found in our article in the regional markets the tungsten consumption of steel differs considerably, December 2005 issue of the ITIA Newsletter. from 2 % in the USA to about 10 % in Europe and Japan and to about 30 % in Russia and China The development of high speed steels (HSS) is illustrated by Table 1, indicating that tungsten played the leading part from the very 2. WHAT IS THE EFFECT OF TUNGSTEN IN STEEL beginning. [ 1,2,5,6 ] Today, tungsten is used as an alloying element in steels for the following When added to steel, tungsten forms tungsten carbides or complex steel grades [2,5,6]: carbides with other carbide forming elements, such as chromium, molybdenum and vanadium but also iron. It increases the amount of • High speed steels (HSS) – in general terminology they are undissolved and excess carbide in the hardened steel, and the eutectoid often simply called tungsten steels – this steel consumes most of the tungsten used in steelmaking point is shifted towards lower carbon concentrations. The consequence is the precipitation of fine or very fine grained carbides evenly • Hot work tool steels distributed in the steel matrix. The chemistry of these carbides depends • Cold work tool steels on the concentration of carbon and the alloying elements present as well • Plastic mould tool steels as on the heat treatment applied. Complex carbides (M6C, M23C6, MC) • Heat and creep resistant steels are responsible for retaining a fine-grained steel matrix by retarding the • Corrosion resistant stainless steels and valve steels grain growth during heat treatment. The addition of tungsten will produce a larger carbide volume than other alloying elements – at the Table 1: Early history of high speed steels [1-4]. same carbon level [1]. year C Cr W Mo V Si/Mn Co remarks 1868 1.5-2.4 0.5 5.0-8.0 - - ~1.0/2.0 - Mushet; first “self-hardening” steel Good wear resistance is the most 1886 2.0 12.0 � � Brustlein; J.Iron Steel Inst. 1886 important property of tool steels, and 1898 1.8 3.8 8.0 -- - Taylor-Wight (“overheated”) tungsten, next to vanadium, is the most 1905 0.25-2.0 1-7.0 4-30.0 2-15.0 0.1-1.0 Mathews US 779,171 effective carbide forming element for alt. to W increasing wear resistance. Furthermore, 1906 0.68 5.95 17.81 - 0.32 Taylor-Wight 1910 0.8 4.0 18.0 - 1.0 - McKenna tungsten significantly improves the hot 1912 0.8 4.0 18.0 - 1.0 5.0 hardness and hot strength of steel and addition of Co 1923 0.8 4.0 18.0 - 1.0 12.0 leads to increased yield strength and 1939 1.4 4.0 18.0 - 2.0-5.0 - high C, high V tensile strength without adversely � � - 9.0 � � affecting ductility and fracture toughness. 1940 W replaced fully or partially by Mo � � 6.0 5.0 2.0 - 2 �..not further specified The effects of tungsten on steel properties in terms of carbide volume, coarsening. At higher temperatures, the fine carbides coalesce and the shape and distribution, and fine-grained structure are [1]: effect is lost. - more carbides and harder carbides increase hardness and wear resistance The effect of tungsten alloying on hardness during tempering is schematically shown in Fig.1. During tempering at relatively high - fine carbides and a fine-grained structure result in higher temperatures, nm-size carbides are precipitated that generate toughness for a given hardness level. “secondary hardening” (see below). The high hot and red hardness (which is the retention of hot hardness over long-term exposure to high temperatures) and the high hot strength In very hard tool steels, for example, cold work steels tempered at low are the result of a microstructure containing numerous high-alloy temperature, the wear resistance is caused mainly by primary carbides carbides of a composition that enables precipitation hardening by which are not affected by hardening. These carbides are small and evenly age-resistant carbides and solid solution strengthening. distributed and very hard (heavy-duty cold work tools). Fine grained martensite adds to this effect. In some low carbon steels, as, for example, in case of creep resistant martensitic Cr Steels, precipitation strengthening by intermetallic phases 4. FACTORS IN THE CHOICE OF TUNGSTEN AS occurs during creep exposure, such as Laves phases: Fe2(Mo,W).
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