STEEL WIRE AND NAIL MAKING. The importance of the steel wire and nail in dustry in the United States may be measured by the fact that in 1902 there was produced a total of 1,574,293 tons of wire rods of which nearly 500,000 tons were made into wire nails. In 1909 the production of wire rods was 2,514, 504 tons, valued at $67,440.000. The 1918 out put is estimated as 3,000,000 tons, of the value of $100,000,000. About one-fourth of this goes into nails. Time was when both wire and nails were manufactured entirely from wrought iron, and to secure the toughness and high tensile strength required, great care had to be used in the preparation of the iron, the cost of the prod uct being proportionately high. It was only a question of time before steel, because of its less cost and its high strength, became the standard material in this as in other branches of the iron and steel industry; and today practically the whole of the wire and wire nails used are made from either Bessemer or open-hearth steel, the latter being specified where wire of the special grades with higher physical prop erties is required.
Physical Properties of Steel As showing the great increase in strength of steel over iron wire, it may be mentioned that while good black iron wire will show an ultimate tensile strength of about 25 tons to the square inch, and bright hard-drawn wire a strength of 35 tons to the square inch, Bessemer steel wire will stand a strain of 40 tons and open-hearth steel wire 60 tons to the inch. Of the 'Ispecialp grades of wire a high-carbon open-hearth steel will stand about 80 tons, crucible cast-steel wire about 100 tons, and the best cast steel, or as it is sometimes called, °plow* steel wire, 120 tons to the square inch; while certain qualities of cast-steel wire, made under specifications calling for a particular composition and requiring very elaborate working, have been produced, showing an ultimate breaking strength of from 150 to 170 tons to the square inch; The process of wire-drawing serves greatly to improve the physical qualities, and the smaller the size to which the wire is drawn down the greater is the ultimate breaking strength. The wonderful
qualities of piano wire are proverbial, the average strength of English piano wire as given by the manufacturers ranging from 225 pounds for No. 12 music wire gauge, which is 0.029 inch in diameter, to 650 pounds breaking strength for No. 22, which is 0.052 inch in diameter. Re duced to the square-inch unit, the ultimate ten sile strength per square inch would range from 300,000 pounds to 340,000 pounds. The com position of this remarkable wire is as follows: Carbon, 0.570; silicon, 0.090; sulphur, 0.011; phosphorus, 0.018; manganese, 0.425. An analy sis of another wire of unusual strength known as "plow,o shows 0.828 per cent of carbon, 0.587 per cent of manganese, 0.143 per cent of silicon, 0.009 per cent of sulphur, 0.030 per cent of copper and no phosphorus. The tests of this wire ran from 200,000 pounds per square inch for wire 0.191 inch in diameter to 350,000 pounds for wire 0.093 inch in diameter. Of course, with such high tensile strength the elongation or stretch was very small, ranging from 0.75 to 1.1 per cent only.
Billet bulk of the wire and wire nails of commerce are manufactured from Bes semer billets. Open-hearth billets are worked up into rods for the manufacture of chain, for special grades of wire and for various finished products in which high tensile strength is called for. In each rod mill billet continuous-heating furnaces are continually at work. The billets, which are 4 X 4 inches in section and 36 inches in length, are fed transversely into the furnace, side by side. They are pushed through the fur nace door by a hydraulic charging machine, and by the time they have been heated to the proper temperature for rolling, they are pushed, one after the other, out through the rear door of the furnace and fall upon a conveyor, by which they are carried down into the rod mill.