Transactions of the American Foundrymen's Association, Volume 26
By American Foundrymen's Association 1918
Mr. A. O. Backert:—Mr. Chairman, I think this paper is too important to permit it to go by without adequate discussion. We are informed by the ordnance department that the time has not yet arrived for the use of cast iron for shell purposes in this country. We think this is mighty unfortunate. At the League Island Navy Yard in Philadelphia they were making permanent molds by the Custer process and today semisteel shells are being made, but of course the shells are used only for practice purposes. This shell question is all important, and it does seem to me that if the cast-iron shell can be used successfully by our enemies, it likewise can be used successfully by us. I would like to ask Major Custer if he can tell us why hand grenades are more satisfactory and have greater destructive power when made of malleable iron instead of semisteel, cast iron or steel ?
Major E. A. Custer:—It is due to the peculiar toughness of malleable iron. That is the only thing I can say. Ordinary foundry iron will invariably powder when a high explosive is used. The walls of the hand grenades are comparatively uniform in thickness, and the nearer you get your walls to uniformity, the better fragmentation you will get, given the same explosive effect in each case. In the case of malleable-iron hand grenades there is no initial shock, and all you have to provide in that case is the ability to fragment properly. You have no occasion to look further than that. If it were not for the initial shock it would not be difficult to make a cast-iron shell that would be perfect in fragmentation. You must have toughness and rigidity in the casting in order to successfully meet the requirements. That is the only explanation I have.
The Chairman, Mr. A. W. Walker:—Mr. Fuller, can you add anything to this question?
Mr. B. D. Fuller:—I don't know that I can, except to say I have been interested in experiments which have been conducted along the lines spoken of by the secretary and Mr. Custer—experiments dealing with the difference between the efficiency of the cast-iron and malleable-iron hand grenades. We found that when the cast-iron hand grenade is exploded there remains scarcely anything of it except powder. I don't know how effective the semisteel was although I think it was not much more satisfactory. Malleable iron seems to be the effective material in that there is larger fragmentation. For instance, a cast-iron grenade exploded inside a pine box about an inch thick did not do the desired damage, not nearly the damage that the malleable-iron grenade did. The fragments of the malleable iron grenade went through the inch board like a bullet, whereas the pieces of the cast-iron grenade did not. The government, while I cannot speak authoritatively, seems to be of the opinion today that malleable iron is to be used in the manufacture of grenades to an almost exclusive extent.
