THE HARDEST ALLOY.
Tungsten carbide, consisting of carbon and tungsten approximately in proportions of 95 per cent, tungsten and 5 per cent carbon, is the hardest alloy known. It was made on' a laboratory scale in 1915, but though of interest to metallurgists it was so extremely brittle that it had no practical usefulness. Improved methods of working, and in some cases the addition of cobalt, with or. without a minute quantity of iron, have now given tungsten carbide a tenacity that enables it to be used for tipping cutting tools. The results obtained are remarkable. In an automatic chucking machine in which tungsten carbide tools had been substituted for those of high-speed steel it was found possible to machine 27,000 bronze valve discs, whereas with the finest quality of high-speed steel regrinding was necessary after 600 pieces had been machined. The finishing operation was carried out with tungsten carbide tools, and after producing 28,000 parts their cutting edges showed no preceptible signs of breaking down.
Tungsten carbide is 250 times as hard as lead, 20 times as hard as decarburised iron, and about 2 3-5 times as hard as hardened 0.4 C. steel.
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Bibliographic details
Waipa Post, Volume 39, Issue 3087, 10 December 1929, Page 3
Word Count
194THE HARDEST ALLOY. Waipa Post, Volume 39, Issue 3087, 10 December 1929, Page 3
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