Fig. 165.—Another Sectional View of an Open-hearth Furnace.
When the furnace has been charged, the gas and air are allowed to enter at intervals of fifteen minutes, first from one side, then from the other. When the air and gas enter one side, the exhaust or waste gases pass out through the other side. The reversing is done by means of levers which open and close the valves. A sectional view is given in [Fig. 165], showing the air and gas chambers and the brick checker work through which the air and gas pass and are heated. The broken lines represent the passages leading to these chambers; the valves are also shown.
Fig. 166.—Open-hearth Furnace Discharging.
When the metal has been fused sufficiently, a sample is dipped out and analyzed, so that its composition may be known and sufficient carbonizing material added to produce the desired quality. This is not possible with the Bessemer process. It is finally tapped into a large ladle, from which it is poured into molds forming the ingots, which are treated in the same way as described in the Bessemer process. The discharging is shown in [Fig. 166].
Questions for Review
What methods are used for converting pig iron into wrought iron? Describe in full the two methods. What other name is sometimes given to the puddling process? Why is it so named? Explain the process of puddling. How is the first product of the puddling process treated? What is the object of this treatment? What is steel? Name the different qualities, giving the approximate carbon contents of each. What is the old test for iron and steel? How was “blister” steel produced? By what process is cast or tool steel made? What sort of vessel is used in melting the materials? State the differences between making tool and soft steel. What is an ingot? What is the difference between an ingot of tool steel and an ingot of soft steel? What is meant by the piped end of a tool steel ingot? How are these ingots classified? How is octagon tool steel made? What processes are used in making soft steel? Describe each. Which is the most satisfactory? Which is the most rapid? Why is the product of the open-hearth process the best? What is the purpose of “soaking” the ingots?