Book Description

Excerpt from The Philadelphia Correspondence Schools of Foundry Practice: Dr. Edward Kirk's System of Foundry Practice; Semi-Steel, Cupola Steel Castings, Malleable Steel Castings Semi-steel is a mixture of cast iron and steel scrap melted together in a cupola furnace, in contact with the melting fuel. A true semi-steel is composed of 50 percent cast iron and 50 percent, steel, but these proportions are seldom used in making mixtures, as it has been found that a smaller percent, of steel gives equally as good results and with more certainty of an even grade of semi-steel than the larger per cent, for castings desired to be soft and strong. But it is the common practice to call all cast iron containing steel a semi-steel. Steel is melted with cast iron for the purpose of increasing the strength of the iron, reducing the size of the crystalline structure of the iron and making a denser and closer metal that finishes and polishes similar to steel and gives a better wearing surface. Also to reduce the porousness of the iron and prevent leakage or sweating of the metal in fittings, valves, etc. Owing to the wide difference in the characteristics in foundry pig, made from different ores, or smelted with different fuels, pig from the different furnaces frequently give different results when melted with steel and cast iron, even when showing the same analysis of the four elements commonly analyzed for in pig. For this reason no definite percent, of steel that gives the best results can be stated that will apply to all iron. A founder's best guide, in making mixtures of semi-steel for the various lines of castings, is in the analysis of the iron; but this cannot always be depended upon, and more or less experimental work is sometimes necessary to obtain the best results. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.