STRENGTH Of ARTILLERY STEEL.

Pukekohe & Waiuku Times, Volume 4, Issue 90, 1 October 1915, Page 2 (Supplement)

STRENGTH Of ARTILLERY STEEL.

WHEN GERMANY IS BOUND TO FAIL. Modern high-powered guns could not be built without steel strong enough to resist the enormous pressures to which they are subjected. Few understand how groat these pressures are—almost as far beyond ordinary comprehension as are the distances of the stars or the number of atoms in a glass of water. An attempt to state the matter in a form that will mean something to the ordinary mind is made by a contributor to "La Nature" in an article entitled "The Strains Resisted by GunMetal." He "writes:—

"When the marvels of modern artillery .are described, perhaps we direct our admiration too exclusively to the mechanicians who have combined to construct it. We must not, however, forget the metallurgist for it is owing to the astonishing qualities of the metal that the gun is so well able to resist the enormous strain due to the detonation of the explosive. "It is interesting to cite here some figures published by Commandant Regnault. At cacti discharge of a gun, in the case of our field-pieces, in less than three-tenths of a second the pressure exceeds twenty torus to the square inch, and the speed of the projectile leaving the muzzle is more than 2,i>00 feet a second.

"The energy developed may be put at about half a million foot-pounds; in other words, considering the cannon as a motor working during an exceedingly short time, we may place its rating at about twenty million horse-power. "Not only must the metal be able to resist these strains time after time, but to do so under unfavourable conditions, such as the high temperatures produced by the explosives. And not only must the metal of the gun be as strong as this,, but it is the same with that of the shell. The shell of our 'seventyfive' support a pressure estimated at seventeen tons; the work of the device that takes up the recoil reaches about twelve tons to the square inch, and the

mount neutralize* at each discharge about two tons.

"In fact, these conditions are realized in quit© a remarkable way. It has been possible to test in the machineshop the pieces of a battery that has fired several thousand shots and to show that they have suffered not tho slightest deformation. "This is why it is necessary to employ special steels. The use of nickel, in proportions of 1 per cent, to 2 per cent., gives to steel special qualities. This is one of the points where the economic blockade to which the Germans are subjected in likely to cause them great trouble when it becomes necessary for them to renew their war material. For nickel comes exclusively from New Caledonia and Canada, that is to say, from a French colony and a British one. When the Germans, there, fore, have used up their stock, there will be no source from which to replenish it."