GOOD ENGINEERING MATERIALS SHOULD NOT BE MISUSED

FRANKLIN L. EVERETT Associate Professor of Engineering Mechanics University of Michigan, Ann Arbor, Mich. New names of important materials are appearing in our everyday reading and in the technical literature. These include both ferrous and non-ferrous metals, plastics and even substances found abundantly on the surface of the earth. It has been said that almost anything can be made but that it is the particular problem of the engineer to see that it is made economically. The engineer is constantly making decisions involving the selection of the most suitable material and the proper shape and the best design. Moreover, he must arrive at a workable solution in a reasonable time so that people may use his product. There is always an opportunity to pursue the problem of’ making later improvements. This article literally hits some high spots by naming some extremely interesting new materials which have exhibited outstanding properties such as high strength, low density, excellent resistance to chemical deterioration and destruction by high temperature. DUKTILIRON is the trade name of the International Nickel Company for the process it will license to common grey iron foundries for making a new high-strength and high-elongation iron out of their regular grey cast iron. This will be accomplished by adding a magnesium alloy (almost any alloy) containing about 15 per cent Mg, to the grey iron at 2750°F., in the ladle before the iron is poured. Some of the magnesium comes out to the surface of the molten iron as slag but about 0.6 per cent Mg is residual in an uncombined state. The amazing result is the production of spheroidal graphite with consequent marked improvement of mechanical properties. The International Nickel Company has made great research advances over the original patented process of Nodular iron by the British. In the British process Cesium instead of Magnesium was used. In the research program on Duktiliron, it has been found that the tensile strength increases as the content of silicon is increased from 0 to 5.5 per cent; and the ductility decreases as the amount of carbon increases from 2 to 4.5 per cent. The maximum tensile strength of 110,000 Ibs./sq. in. and 30 per cent elongation has been obtained by subjecting the material to a heat treatment. Duktiliron is intended to compete with the usual malleable iron. It is cheaper even now. Malleable iron has a tensile strength of about