ON THE BLACK RESIDUE PRODUCED IN TREATING CARBON STEEL RODS FOR MAKING WIRE BY THE H2SO4-METHOD (I)

Abstract

Three kinds of rods employed as samples in this experiment, were rods for card-clothing-wire, and piano-wire, and rope-wire. They were made in Japan, Sweden, England, Belgium, Switzerland, France, and U.S.A. The samples were dissolved in H₂SO₄ (1:5) by warming on water bath with taking precaution against rising of the temperature of acid above 90°C, and black residues thus produced were compared with each other. It was found that the quantities of the residues were different from each other, although the steel rods had the same carbon content, and the residues of Japanese rods were larger in quantity than those of foreign rods.
For examples, the composition of some rods were as follows: C 3.6-5.0%, Si 3.36-10.47%, Mn 0.39-0.63%, S 0.31-0.39%, Ni 1.57-1.96%, Cr .0%, Cu 6.23-14.62%, and Fe 28.3-45.3%. Most part of carbide, silicon compound, sulphide and nicke], almost all parts of metallic iron and manganese compound, all part of Cr were dissolved but all part of copper remained undissolved.