Abstract
Tests were conducted with the object of verifying reports that the mechanical properties of steels made from spongy iron excelled those of steels made from scrap iron. In Experiment I, as a preliminary test, comparisons were made of the mechanical properties of carbon steel made from the two methods just mentioned, for which purpose from five to six suitable kinds of this steel with carbon contents ranging from 0·2% to 1·3% were selected ahd tested. Contrary to expectations, the steel made from scrap iron was found to be tougher and harder.
According to Experiment II, the mechanical properties of steels made from the two processes and with the same range of carbon contents as in the preccding experiment, under five different heat treatments, were compared with the same results as in Experiment I, except that the steel made from spongy iron, although tough, was clearly found to be inferior in strength.
In Experiments III and IV, the same comparative tests were made with nickel-chrome steel of thirty different compositions and under seven different heat treatments, with the result that the steel made from spongy iron was much tougher and harder than that made from scrap iron.
In the foregoing Experiments I-IV, the test-pieces were obtained from ingots weighing 9kg each, and tested for tension and impact. In Experiment V, which was supplementary to the others, the test pieces were obtained from ingots weighing about 230kg, the experiments being for torsion and fatigue, and for their mechanical properties at high temperatures. The foregoing experiments amply proved the higher mechanical properties of steels made from spongy iron than that of steels made frotn scrap iron.
