TUNGSTEN. 



:>05 



heavy cutting work the nose or point of a high speed steel tool may 

 become red hot, and yet such a tool will continue to cut for long 

 periods in that state without breaking down. 



Tungsten steels then, prepared with suitable admixtures of 

 other metals, such as chromium and vanadium, are not only ex- 

 ceedingly hard, but, in addition, maintain their hardness at high 

 temperatures. Speaking roughly, it may be said that the chromium 

 in these steels provides the hardness, while tungsten produces the 

 self-hardening properties by raising the temperature at which 

 tempering begins. 



A finished high speed steel as employed for making the best tools 

 contains 18 per cent, to 20 per cent, of tungsten. Its qualities may 

 be impaired or even destroyed by quite small quantities of certain 

 other elements such as tin, sulphur, phosphorus, arsenic, manganese 

 or copper. The necessity for preparing the ores used in the metal- 

 lurgy of tungsten as clean as possible need not be emphasized, for 

 errors are very costly and wasteful and deleterious impurities are 

 not, as a rule, detected until an advanced stage in the manufacture 

 or even after the tool has been put to work. 



A recent American writer has drawn attention to the fact that, 

 " whereas in the wars of the past brass and lead, were, next to steel, 

 the most important ' martial metals,' to-day tungsten alloyed 

 as high speed steel is the dominating factor. To deprive a nation 

 of tungsten is to cripple its military power, and its industrial power 

 in times of peace." 



The introduction of high speed steel, according to the Advisory 

 Council of Science and Industry, of Australia, marks one of the 

 greatest advances ever made in the metallurgy of iron and steel, 

 and has completely revolutionized the machine shop business of 

 the whole civilized world, affording largely increased outputs with 

 commensurate lower costs. Another author states that under 

 favourable conditions one man and one lathe can do as much work 

 with high speed tungsten steels as five men and five lathes could 

 formerly do with simple carbon steels. 



Most of this account of the uses of tungsten has been prepared 

 from the papers enumerated below and the reader who is desirous 

 of following the subject further is referred to them. 



(1) "The Manufacture and Uses of Ferro-alloys and Alloy 

 Steels." Advisory Council of Science and Industry, Com- 

 monwealth of Australia. Bull. No. 9. Melbourne 1918. 



