SOME UNFAMILIAR METAL.

Otago Witness, Issue 3275, 20 December 1916, Page 64

SOME UNFAMILIAR METAL.

By L. L. Blackneli

Several unfamiliar metals have come info prominence since the outbreak of the great war. on account of their greatly increased use in connection with the production ot armaments. A great demand has arisen for "special" steels, the hardness and toughness of which depend on the presence of such ingredients as the metals tungsten, chromium, and vanadium. One ot the most important uses of these specially hard steels is'fur making "high-speed" machine tools—that is to say. .tools which retain their hardness, and hence their cutting power, even when heated to redness by the friction of the work which is being done. A machinist can cut steel or iron six times as fast with a lathe tool of highspeed steel as with one of carbon steel, because with the latter the cutting speed must be slow, so that the tool is not heated by the friction above a certain temperature, lest it be softened. Orders for special steels have been received by Sheffield steelmakers during the past 18 months from Russia, Fiance, Italy, and the United States, as well as from users at home of a magnitude never before experienced or even contemplated by them. In the manufacture of hard steels, ferrotungsten, ferro-chromium, or ferro-vana-dium, which are alloys of these metals with iron, is added to steel, either alone or in comhination with nickel or manganese, or with each other. Sheffield steelmakers have experimented with electric furnaces for making highspeed steel, but they are not yet convinced that as good an article is obtained as by the old-established crucible process in which smaller quantities are handled at one time. Nevertheless a number of electric furnaces have been installed during the past vear, and a largely increased out put of alloy steel for motor parts aeroplanes, and' small castings has resulted. Tungsten. —

Before the war British steelmakers were almost entirely dependent on Germany for supplies of refined tungsten, notwithstanding the fact that the chief source of supply Of wolfram, the ore of tungsten, is in the British Empire—namely, in Burma. Important quantities of wolfram ore are also produced in Australia, whilst there is a not inconsiderable output in Cornwall. On the outbreak of war it was speedily realised that the establishment ot a tungsten refinery in this country was ot the utmost importance, and by co-opera-tion and energetic action on the part ot the steelmakers this was very quickly accomplished. Regulations have been made lor controlling the export of wolfram ore from the British territories where it Ls mined, and it is hoped to induce the government to continue regulations after the conclusion of peace in order that the refining of tungsten and the manufacture of high-speed steel may be retained in British hands. The quantity of tungsten present in etittine-tools is often as much as H to S per cent. In addition to its use for auo?ing with steel, tungsten has been faraelv used in Germany for the manufacture of metal filament electric lamps m ner cent of tungsten and a maximum of rpe?cent of carbon, is from 6s 6d to 7s a lb. Chromium. — To the majority of people chromium is mcS familiar 3 in the compouri. which are used as P'B™f rlants and tanning powders, .he value 01 Wit £ "'Si CfuSSttool^ making steel tor cmi deposits of and armour-plates. J toe »*ss£ terri?h^ mi namX n BhSesia. The ore is -.7 «t Selukwe, and transported by mined at oeiuuw , Africa to rail across Portuguese tart A™ Jttufof eCe iv «» m«» £3B per ton. 1 —Vanadium.— i nnrnmprcial source ot The principal con ™ e ™ a ' t Ls " Pe ru, i,- ni vanadium at pie■ oi.l i~ «- » snpplj of varum known and where the c"" 1 Tf ntrV n Here a black worked found, having mineral called pa«<»J* a coaL In contains t i 6 WS con oflree sulphur, which about 30 pei cent, oi ij contaimng of vibration. An is that weight the use of vanadium eel is aion % f can be reduced i '' c e % a waller heavy, machmery -by the gteeL quantity of in France Vanadium was fb st used about 20 jeais them t(J plates, teßt » t ?' "} tou«hiiesß and resistP°f c eSS t£ added ? n UC the form o to ord nary engineering struct™a o .^ 25 P? would contain *lb of vanadium tool steels as vanadium. In be preS ent. worth Us 6d a lb.

Molybdenum.— \ few rears molybdenum was of quite small importance. It was during the war between Turkey and Bulgaria in 1912 that the value of molybdenum steel in tlie manufacture of field-guns was first demoncrated, and during succeeding years the

demand for molybdenum increased and the price rose rapidly. Now the chief ore of molybdenum—molybdenite —is worth £470 a ton. The addition of a small proportion of molybdenum, in the form of ferromolybdenum, to steel greatly increases the hardness and toughness of the metal, and machine tools made of molybdenum steel retain their cutting properties even though raised to a high temperature. Ferromolybdenum containing 70 to 80 per cent, of molybdenum realises 15s 6d per lb. New South Wales and Queensland are the world's largest producers of molybdenum ores. Canada possesses deposits of molybdenite which -will no doubt become of commercial importance, but at present the production of the ore is small. Of molybdenum ores, as of so many other valuable minerals, the British Empire possesses ample supplies, and it is to be hoped that regulations will be made eo that after the war the deposits may not get under foreign control, but be exploited by British enterprise for the advantage of British industries.—Chambers' Journal.